UWC-MU Plant Science Symposium

“Sustainable Food Security and Environmental Ecosystems for World Prosperity”

Life Sciences Building

University of the Western Cape

Bellville

SOUTH AFRICA

14 June – 18 June 2015

Life Science Auditorium

CONTENTS WELCOME ........................................................................................................................ 1 ACKNOWLEDGEMENTS ..................................................................................................... 2 ORGANIZING COMMITTEE AND ADMINISTRATORS ........................................................... 3 SCHEDULE……………………………………………………………………………………………………………………..4-8 ABSTRACTS……………………………………………………………………………………………………………….…9-38 MJ Oliver .................................................................................................................................... 9 MS Rafudeen….………………………………………………………………………………………………………….…….…10 JM Rohwer ............................................................................................................................... 11 BK Ndimba ................................................................................................................................ 12 D Braun .................................................................................................................................... 13 T Masehela ............................................................................................................................... 14 R Ingle ....................................................................................................................................... 15 AR Durbak ................................................................................................................................ 16 SL Murray……………….……………………………………………………………………………………………………….…17 RE Sharp ................................................................................................................................... 18 P Hills ........................................................................................................................................ 19 LN Moleleki…….……………………………………………………………………………………………………………….…20 A Gokul ..................................................................................................................................... 21 A Heese .................................................................................................................................... 22 D Mendoza-Cozatl .................................................................................................................... 23 N Ludidi…..………………………………………………………………………………………………………………………….24 L Donaldson .............................................................................................................................. 25 ME Makgopa ............................................................................................................................ 26 FB Fritschi ................................................................................................................................. 27 JM Farrant ................................................................................................................................ 28 NP Makunga ............................................................................................................................. 29 W Gassmann…….………………………………………………………………………………………………………………..30 M Keyster…….…………………………………………………………………………………………………………………….31 I Taylor...................................................................................................................................... 32 J May ........................................................................................................................................ 33 P McSteen ................................................................................................................................ 34 K Phillips ................................................................................................................................... 35 J Washburn .............................................................................................................................. 36 A Klein……...………………………………………………………………………………………………………………………..37 SC Peck ..................................................................................................................................... 38 LIST OF DELEGATES…………………………………………………………………………………………………………….39 MAPS/DIRECTIONS (CPT Int. Airport to the University of the Western Cape).…………………...40

Note: There will be signposts at the entrance of the University of the Western Cape to direct delegates to the Auditorium (Symposium Venue) of the Life Sciences Building.

Photographing, video recording or audio recording of presentations by any delegate is prohibited unless the presenting delegate grants permission for such.

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Welcome

The UWC-MU Plant Science Symposium is a result of interaction between Prof Ndiko Ludidi in the Department of Biotechnology at the University of the Western Cape (UWC) and Prof Robert Sharp of the Interdisciplinary Plant Group at the University of Missouri (MU). The interaction started in 2014 when Prof Ludidi visited MU on a University of Missouri South African Education Program (UMSAEP) award.

The UWC-MU Plant Science Symposium is aimed as a vehicle to further advance the cooperation between UWC and MU. It aims to bring together relevant UWC and MU plant scientists whose research interests in plant abiotic and biotic stresses impact on Food Security and Environmental Sustainability. It also aims to promote interaction between UWC and the University of Pretoria in areas of research that have a bearing on the activities of the Department of Science and Technology-National Research Foundation Center of Excellence in Food Security (DST-NRF CoE in Food Security), which is co-hosted by these two universities. The symposium is also seen as an opportunity to strengthen interaction between UWC, the University of Cape Town and Stellenbosch University in plant science research.

Prof Julian May (Director: DST-NRF CoE in Food Security)

University of the Western Cape Bellville

Cape Town South Africa

Prof Ndiko Ludidi (Chairperson: Department of Biotechnology)

University of the Western Cape Bellville

Cape Town South Africa

Prof Robert Sharp (Director: Interdisciplinary Plant Group

University of Missouri Columbina Missouri

United States of America

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Acknowledgements

The UWC-MU Plant Science Symposium was made possible by generous support from the DST-NRF Center of Excellence in Food Security, the University of the Western Cape (UWC), the University of Missouri (MU) and the Interdisciplinary Plant Group (IPG) at the University of Missouri.

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Organizing Committee and Administrators

Prof Ndiko Ludidi (Department of Biotechnology, UWC), Prof Robert Sharp (IPG, MU), Prof Julian May (DST-NRF CoE in Food Security, UWC), Dr Marshall Keyster (Department of Biotechnology, UWC), Dr Ashwil Klein (Department of Biotechnology, UWC) and Mr Arun Gokul (Department of Biotechnology, UWC) constituted the organizing committee of the UWC-MU Plant Science Symposium.

Victoria Brian (IPG, MU) and Elaine Petersen (DST-NRF CoE in Food Security, UWC) constituted the administrative team of the UWC-MU Plant Science Symposium.

Prof Ndiko Ludidi Prof Robert (Bob) Sharp Prof Julian May

Dr Marshall Keyster Dr Ashwil Klein Mr Arun Gokul

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SCHEDULE Sunday, 14 June 2015

18h30 – 21h30…………………………………..…Welcoming Dinner (Poplars Restaurant, Durbanville)

Monday, 15 June 2015: Life Science Building, UWC

Session 1 (Chairperson: Ndiko Ludidi)

08h20 – 09h10……………………………………............................................Registration and Breakfast

09h10 – 09h15…………………………….Welcoming (Ndiko Ludidi, University of the Western Cape)

09h15 – 09h30……Opening Address (Prof Vivian Lawack, Deputy Vice-Chancellor: Academic;

SIF Prof Frans Swanepoel, Deputy Vice-Chancellor: Research & Innovation)

09h30 – 09h40…………The diversity of research activities in the Department of Biotechnology

at UWC (Ndiko Ludidi)

09h40 – 09h55………………Profile of the IPG: MU contributes to global impact of Plant Science

research (Robert Sharp)

09h55 – 10h25…………….……Water-deficit regulation of gene expression in the maize primary

root: miRNAs and transcription factor profiling (Melvin Oliver)

10h25 – 10h55……………….A proteomic approach to investigate the response of Eragrostis tef

to drought (Suhail Rafudeen)

10h55 – 11h15……………………………………………………………………………………………………Coffee Break

Session 2 (Chairperson: Marshall Keyster)

11h15 – 11h45………...............Kinetic modelling as a tool for understanding and manipulating

plant metabolism (Johann Rohwer)

11h45 – 12h15…………………..…National Agricultural Proteomics Research & Services Unit and

applications of proteomics in Agricultural Biotechnology

(Bongani Ndimba)

12h30 – 14h00……………………………………………………………………………………………………………...Lunch

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Monday, 15 June 2015: Life Science Building, UWC

Session 3 (Chairperson: Ashwil Klein)

14h00 – 14h30………………Characterizing genes controlling carbohydrate partitioning in maize

in response to heat and drought stress (David Braun)

14h30 – 15h00…………….…Working towards environmental sustainability by monitoring GMO

impacts on biodiversity and the environment (Tlou Masehela)

15h00 – 15h30…………………Regulation of plant immunity by the circadian clock (Robert Ingle)

15h30 – 15h45……………………………………………………………………………………………………Coffee Break

15h45 – 16h15……...Beyond the wall: characterizing the role of boron in maize development

(Amanda Durbak)

16h15 – 16h45……………Characterisation of phytoalexin accumulation in maize infected with

Cercospora zeina, causal organism of grey leaf spot disease in South

Africa (Shane Murray)

Tuesday, 16 June 2015: Life Science Building, UWC

Session 1 (Chairperson: Ndiko Ludidi)

08h30 – 09h20……………………………………............................................Registration and Breakfast

09h20 – 09h50…………………….Root growth under water deficits: Physiological complexity and

coordination (Robert Sharp)

09h50 – 10h20……………Overexpression of microbial volatile biosynthetic genes for enhanced

growth in Arabidopsis (Paul Hills)

10h20 – 10h50……………….Transcriptome profiling of long noncoding RNAs involved in potato

responses to Pectobacterium spp (Lucy Moleleki)

10h50 – 11h15……………………………………………………………………………………………………Coffee break

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Tuesday, 16 June 2015: Life Science Building, UWC

Session 2 (Chairperson: Ndiko Ludidi)

11h15 – 11h45…….…3,3-Diindolylmethane mediated signaling and its role in Brassica napus

L. seedling response to vanadium stress (Arun Gokul)

11h45 – 12h15…………Role of vesicular trafficking proteins in plant innate immune responses

against bacterial pathogens (Antje Heese)

12h30 – 14h00……………………………………………………………………………………………………………...Lunch

Session 3 (Chairperson: Marshall Keyster)

14h00 – 14h30……………………Molecular mechanisms of phloem transport and seed loading of

heavy metals (David Mendoza-Cozatl)

14h30 – 15h00……………Inhibition of nitric oxide synthase activity alters antioxidant activity

in Vicia faba (Ndiko Ludidi)

15h00 – 15h30…………….…Transcriptomic analysis of the response of Arabidopsis to the ionic

and osmotic components of salinity stress (Lara Donaldson)

15h30 – 15h45……………………………………………………………………………………………………Coffee Break

15h45 – 16h15………………Ectopic expression of a phytocystatin, oryzacystatin-I (OCI) leads to

enhanced drought tolerance in soybean (Eugene Makgopa)

16h15 – 16h45……………….…Leveraging natural genetic variation to increase soybean yields in

water-limited environments (Felix Fritschi)

Wednesday, 17 June 2015: Life Science Building, UWC

Session 1 (Chairperson: Ashwil Klein)

08h30 – 09h20……………………………………............................................Registration and Breakfast

09h20 – 09h50……….……Resurrection plants as models for understanding of what is required

for extreme drought tolerance (Jill Farrant)

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Wednesday, 17 June 2015: Life Science Building, UWC

Session 1 (Chairperson: Ashwil Klein)

09h50 – 10h20……..…Understanding chemical diversity in plants used for medicinal purposes

in the Cape (Nokwanda Makunga)

10h20 – 10h50………Striking a balance: functions of the Arabidopsis immune adaptor protein

SRFR1 (Walter Gassmann)

10h50 – 11h15……………………………………………………………………………………………………Coffee break

Session 2 (Chairperson: Arun Gokul)

11h15 – 11h45………………Effect of exogenous 3,3'-diindolylmethane (DIM) on Brassica napus

seedlings (Marshall Keyster)

11h45 – 12h15…………….A series of genetic suppressors suggests complex regulation of floral

organ abscission in Arabidopsis (Isaiah Taylor)

12h30 – 13h30……………………………………………………………………………………………………………...Lunch

Session 3 (Chairperson: Marshall Keyster)

13h30 – 14h00…………The DST-NRF CoE in Food Security: Role and opportunities (Julian May)

14h00 – 14h30……………………………….……Inflorescence development in maize (Paula McSteen)

14h30 – 15h00………………A novel Zea mays BURP domain-containing gene is involved in the

regulation of maize drought response (Kyle Phillips)

15h00 – 15h30……………Comparative phylogenomic methods for systematics, taxonomy, and

evolutionary studies: an example from the grass tribe Paniceae and

C4 photosynthetic evolution (Jacob Washburn)

15h30 – 15h45……………………………………………………………………………………………………Coffee Break

15h45 – 16h15…………………Biochemical responses of two chia (Salvia hispanica L.) genotypes

to salt stress (Ashwil Klein)

16h15 – 16h45………………Using proteomics to study signaling and secretion during responses

to biotic and abiotic stresses (Scott Peck)

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Thursday, 18 June 2015: Life Science Building, UWC

09h00…………Pick-up from Protea Hotel in Tygervalley (for international participants and

participants from the University of Pretoria) for excursion to Kirstenbosch

Botanical Gardens

10h30…………………………………………...Excursion to Kirstenbosch Botanical Gardens (OPTIONAL)

12h30 – 14h00………………..…Lunch at Moyo’s at Kirstenbosch Botanical Gardens (OPTIONAL)

18h30 – 22h00…………………………………….…..Closing Dinner at Wild Fig Restaurant in Mowbray

NOTE: The visit to Kirstenbosch Botanical Gardens and the lunch at Moyo’s at the Kirstenbosch Botanical Gardens are optional. Participants interested in this excursion, and the accompanying lunch, are requested to please indicate this by Friday the 5th of June 2015.

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ABSTRACTS Mel Oliver, E-mail: Mel.Oliver@ars.usda.gov Water-deficit regulation of gene expression in the maize primary root: miRNAs and transcription factor profiling MJ Oliver1,4, C Seeve1,4, I-J Cho1,4, T Joshi2,4, D Xu2,4, K Riggs3,4, Z Lui5, RE Sharp3,4, D Ware5, MJ McMullen1,4

1USDA-ARS Plant Genetics Research Unit, 2Department of Computer Sciences, 3Division of Plant Sciences, and 4Interdisciplinary Plant Group, University of Missouri, Columbia, Missouri 65211; 5USDA-ARS Plant, Soil and Nutrition Research Unit, Cold Spring Harbor Lab, New York 11724 Under drought conditions, water deficit stress contributes greatly to yield loss. Genetic modification to improve performance under water deficits is a key strategy to mitigate this problem, and understanding the mechanisms of adaptation and acclimation is critical to success. Maize is a prime target for improvement efforts, and is also an ideal model crop, offering a wealth of genetic and genomic information and tools. Under water deficits, roots and leaves undergo various processes to maintain water balance, many of which are driven by alterations in gene expression. To gain insight into how transcriptional responses to water deficits are controlled, we studied the water-deficit response of the maize primary root. Our approach was to identify transcription factor (TF) genes and miRNAs that are temporally regulated under water deficit in the root growth zone (apical 10 mm) using quantitative PCR (TFs) and Illumina sequencing (miRNAs). We chose a well-characterized model system in which the water deficit that the plant experiences is tightly controlled. The model system allowed for the quantification of TFs and miRNAs expression under well-watered, mild (-0.3 MPa) and severe (-1.6 MPa) stress levels. We identified 348 TFs whose expression levels are altered by water deficits in the primary root. Generally, the TFs respond (increase or decrease) within the first 5 h of stress and peak in expression at 26 h. Water deficit stress also significantly altered the expression of several miRNA genes: 16 miRNA families (47 individual miRNAs). We have identified the miRNA/ target relationships both bioinformatically and biologically for each of the responding miRNAs. We are currently validating functional relationships between TF/miRNA expression and plant phenotype. Our aim is to build a molecular regulatory fingerprint for the water deficit response of the maize primary root growth zone and to relate this to strategies for improvement of drought tolerance.

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Suhail Rafudeen, E-mail: Suhail.Rafudeen@uct.ac.za

A Proteomic Approach to Investigate the Response of Eragrostis tef to Drought R Kamies1, JM Farrant1, Z Tadele2, G Cannarozzi2, MS Rafudeen1

1Plant Stress Group, Molecular & Cell Biology Department, UCT, Upper Campus, Rondebosch, 7701. 2Institute of Plant Sciences, Department of Biology, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland. Tef (Eragrostis tef) is an important staple cereal crop grown for both human consumption and as a forage crop. Tef is of great nutritional value, is highly adaptable to environmental conditions and is grown as an insurance crop when drought conditions arise. In order to observe the proteomic profile of Tef under drought conditions, an iTRAQ proteomics approach was undertaken. Mass spectrometry data was searched against the Liliopsida database in UniProt and the Tef transcriptome using PEAKS software, to identify and quantify proteins changing in response to drought. A total of 205 proteins showed statistically significant changes in expression between the Tef hydrated vs. dehydrated leaf tissue. The protein data was also subject to in silico ontological analyses in order to classify proteins into categories of biological function. Validation studies of selected proteins were performed which included physiological enzyme assays and western blot analyses.

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Johann Rohwer, E-mail: jr@sun.ac.za

Kinetic modelling as a tool for understanding and manipulating plant metabolism JM Rohwer Laboratory for Molecular Systems Biology, Department of Biochemistry, Stellenbosch University, 7600 Stellenbosch, South Africa Significant changes occur in sucrose metabolism when moving from immature to mature internodal tissue in sugarcane. In general, sucrose accumulation increases, while growth slows down. To understand all these processes is of central importance, both from a fundamental biochemical point of view and with agro-biotechnological applications in mind. As part of a rational enhancement strategy, we have developed a kinetic model to simulate sucrose metabolism in the sugarcane stalk. The initial model, based on medium-mature sugarcane tissue (internode 5) predicted a number of strategies for increasing sucrose production, such as the knock-down of cytosolic neutral invertase. Subsequently, the model was extended to simulate internodes 3-10 of a sugarcane stalk by modelling growth changes through substitution of internode-specific parameters. Although this model could capture some of the physiological changes during sugarcane stalk maturation, it suffered from the limitation that movement of solute between internodes was not captured. To overcome this, a more integrated model of sucrose accumulation based on partial differential equations was developed, allowing us to model all eight internodes at the same time. The model spans five compartments, the source, phloem, apoplast, symplast and vacuole. Sucrose translocation in the phloem is modelled explicitly, providing a bridge between internodes. The present model provides a comprehensive description of sucrose accumulation and is a rigorous, quantitative framework for future modelling and experimental design.

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Bongani Ndimba, E-mail: NdimbaB@arc.agric.za National Agricultural Proteomics Research & Services Unit and applications of proteomics in Agricultural Biotechnology BK Ndimba ARC Nietvoorbij, Agricultural Research Council, Stellenbosch, 7600, South Africa

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David Braun, E-mail: braundm@missouri.edu Characterizing genes controlling carbohydrate partitioning in maize in response to heat and drought stress D Braun1, T Tran2, RF Baker1, K Leach1, B Julius1, T Dowd2, S Bihmidine1 1Division of Biological Sciences, 2Division of Plant Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri 65211, USA The vast majority of our food supply is derived from cereal grains. Starch and other storage products that accumulate within the seeds are derived from long-distance transport of assimilates through the phloem tissues of veins. Global climate change will impose irregular precipitation and extreme temperature events to agriculture, resulting in reductions in crop productivity, nutrients delivered and stored in seeds, and ultimately yield. The Braun lab is characterizing the functions of genes required for loading sucrose into the phloem in leaves, and the partitioning of carbohydrates to distant sink tissues, including seeds. Through a combination of forward and reverse genetic experiments, we are determining which sucrose transporters and other genes regulate sucrose distribution in plants. Additionally, we are studying how the process of sucrose movement through the phloem is impacted by drought and heat stress. Our goals are to understand which are the key genes controlling carbohydrate partitioning, particularly in response to abiotic stress, to increase crop resilience, improve crop productivity, and food security.

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Tlou Masehela, E-mail: T.Masehela@sanbi.org.za Working towards environmental sustainability by monitoring GMO impacts on biodiversity and the environment TS Masehela Biodiversity Research Assessment & Monitoring, South African National Biodiversity Institute, Kirstenbosch National Botanical Garden, P/Bag X7, Claremont, 7735, South Africa South Africa recognises the potential benefits of using biotechnology as a tool for development in various agricultural practices. As a result, stringent biosafety regulatory systems are in place to ensure that the technology is utilized in a manner that minimizes disruptions to the environment whilst contributing to the country’s sustainable development goals and imperatives. South Africa’s adoption of Genetic Modification, lead to the commercialisation of Genetically Modified Organism (GMOs) such as maize, cotton and soybean. Global food security and economic development incorporates and encourages the use of biotechnological tools for desired outcomes. However, the sustainable use of such technologies is of great concern and may be potentially harmful to the environment. At times, the challenges are characterised by risk assessments, socio-economic concerns, culture and religious beliefs, and individual perceptions. Ideally, the use of biotechnological tools should contribute to the mitigation of various environmental impacts, therefore ensuring their sustainability and that of the environment. SANBI is mandated by the NEMBA Act (ACT no. 14 of 2004) to monitor and report on the environmental impacts of GMOs released into the environment. This is in line with the conservation goals for our biodiversity and towards ensuring the sustainable use of natural resources and the environment for the benefit of the South African society.

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Robert Ingle, E-mail: Robert.Ingle@uct.ac.za Regulation of plant immunity by the circadian clock R Ingle1, N Adams1, V Bhardwaj1, R Joseph1, C Muchapirei1, C Stoker2, K Denby2, L Roden1

1Department of Molecular & Cell Biology, University of Cape Town, South Africa 2School of Life Sciences, University of Warwick, Coventry, United Kingdom The circadian clock is an endogenous time-keeping mechanism that synchronizes biological processes with the external environment, so that they occur at optimal times of the day. While the clock has long been known to play a role in the anticipation of predictable daily changes in abiotic stimuli, it is becoming apparent that it also functions in the anticipation of biotic interactions with pathogens and herbivores. We have demonstrated that Arabidopsis thaliana has circadian clock-mediated variation in resistance against both the biotrophic bacterial pathogen Pseudomonas syringae and the necrotrophic fungal pathogen Botrytis cinerea. To begin to uncover the molecular mechanism by which clock regulation of innate immunity is achieved, we have carried out transcriptome profiling of plants infected at different times of the day with B. cinerea. These experiments revealed that plants are able to mount a more rapid and robust defence response against this pathogen when inoculated at subjective morning rather than in the evening, and suggested a potential role for ethylene and jasmonate signalling in clock regulation of the immune response. Accordingly, we observed loss of temporal variation in immunity to B. cinerea in mutants defective in key components of these signalling pathways.

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Amanda Durbak, E-mail: durbaka@missouri.edu Beyond the wall: characterizing the role of boron in maize development AR Durbak1, K Phillips1, M O'Neill2, S Pike1, W Gassmann1, P McSteen1 1Interdisciplinary Plant Group, University of Missouri, 1201 Rollins Street, Columbia, Missouri 65211, USA 2Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia, 30602 Boron (B) is an essential plant micronutrient, and deficiency results in defects in plant development and significant yield loss. The maize tassel-less1 (tls1) gene encodes a B transporter in the aquaporin family, and tls1 mutants have altered reproductive and vegetative development. tls1 mutants have an overall reduction in B content, with the greatest reduction in young inflorescences (flowering branches), indicating that meristematic tissue is particularly sensitive to B deficiency. Microscopy on tls1 vegetative and reproductive apices shows that tls1 mutants have smaller meristems, suggesting that B plays a role in meristem maintenance. B is best known for its role in cross-linking the cell wall polysaccharide rhamnogalacturonan-II (RG-II). The level of dimerized RG-II in tls1 mutants is significantly reduced in young tls1 inflorescences, indicating that meristem defects may result from altered cell wall properties. However, there are no differences in RG-II cross-linking in tls1 leaves or roots, suggesting that B may have other functions. Historically, there have been reports of B interacting with hormones, namely auxin and cytokinin. tls1 mutants have root defects similar to those seen in cytokinin signaling mutants, and our analysis of double mutants between tls1 and cytokinin or auxin mutants supports an interaction between B and hormones. We propose that cross-talk between auxin, cytokinin, and boron plays a critical role in plant development, and current work is focused on using molecular markers and genetics to dissect the relationship between these hormones and boron in the meristem.

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Shane Murray, E-mail: shane.murray@uct.ac.za Characterisation of phytoalexin accumulation in maize infected with Cercospora zeina, causal organism of grey leaf spot disease in South Africa. J Ntuli, S. Wighard, SL Murray

Department of Molecular and Cell Biology, University of Cape Town, Private Bag, Rondebosch, 7701 Phytoalexins are low molecular weight anti-microbial compounds that are produced in plants in response to pathogen infection. In maize, two classes of non-volatile terpenoid phytoalexins, viz. kauralexins and zealexins, have recently been found to play a role in fungal resistance. Grey leaf spot (GLS) is a foliar disease which severely impacts maize production in South Africa and is caused by the fungal pathogen, Cercospora zeina. Previous microarray and RNA-Seq analyses have indicated that kauralexin and zealexin biosynthetic genes are strongly up-regulated in maize infected with C. zeina. Preliminary GC/MS experiments confirm that kauralexins and zealexins accumulate in C. zeina-infected maize. In order to validate our findings, maize line “B73” was inoculated with C. zeina with the aim to study phytoalexin accumulation and phytoalexin biosynthetic gene expression at three stages of disease development: (i) immediately after inoculation; (ii) at appearance of chlorotic flecks on inoculated leaves; and (iii) once lesions were fully developed. Reverse transcriptase quantitative PCR was carried out to analyse the expression of the phytoalexin biosynthetic genes terpene synthase 6/11 and ent-copalyl diphosphate synthase, which represent the zealexin and kauralexin pathways respectively. Both genes were up-regulated in response to C. zeina infection and correlate with phytoalexin accumulation.

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Robert E. Sharp, E-mail: sharpr@missouri.edu Root Growth under Water Deficits: Physiological Complexity and Coordination RE Sharp Division of Plant Sciences and Interdisciplinary Plant Group, University of Missouri, Columbia, Missouri 65211, USA Root growth is critical for plant adaptation to water deficit conditions, and certain types of roots have the ability to continue growing at water potentials lower than those that inhibit growth of the shoot. This response is shown by the primary root, in which it is important for seedling establishment, and also by the nodal roots of grasses such as maize. Nodal roots are produced from the stem nodes and form the framework of the mature root system; under drought conditions, these roots have to grow through dry surface soil to reach available water at depth. We are addressing the complexity and coordination of mechanisms involved in regulating the growth responses of both primary and nodal roots of maize to low soil water potentials. In water-stressed primary roots, previous work showed that cell elongation is maintained in the apical region of the growth zone but progressively inhibited further from the apex. These responses involve spatially differential regulation of cellular growth processes, including modifications of cell wall extensibility. Current studies include the role of ferulate crosslinks as restraints to cell wall extension in the basal region, using enzymatic and mutant approaches to reduce ferulate levels in the cell wall. Nodal root growth is being studied using a divided root chamber model system to impose precise water deficit conditions around the growing nodal roots while maintaining the primary and seminal roots at high water status. This system mimics the situation in the field where upper soil layers dry and the continued growth of new nodal roots depends on water supplied from already established roots. Initial results show substantial variation in nodal root growth response to low soil water potentials between genotypes, and reveal the importance of root hydraulic properties in determining the relationship between root growth zone and soil water status. With other team members, future studies will integrate physiology and functional genomics to deliver a comprehensive understanding of maize nodal root growth responses to water deficits both in the model system and in the field.

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Paul Hills, E-mail: phills@sun.ac.za Overexpression of microbial volatile biosynthetic genes for enhanced growth in Arabidopsis P Hills, D Dempers, J Kossmann Institute for Plant Biotechnology, Department of Genetics, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa Plant growth promoting rhizobacteria are root colonising bacteria which can influence the growth and development of plants, including enhanced seedling emergence and growth, increased plant biomass and greater crop yields. These effects may be achieved either via the secretion of plant hormones or other, non-hormonal, plant growth regulating substances, including volatile organic compounds (VOCs). The VOCs acetoin and 2,3-butanediol have been shown to promote plant growth as well as enhancing the Induced Systemic Response, consequently enhancing the ability of the plant to deal with pathogen attacks. Acetoin is produced from α-acetolactate via the enzyme α-acetolactate decarboxylase, encoded by the gene AlDc. Acetoin is then coverted to 2,3-butanediol via 2,3-butanediol dehydrogenase, encoded by Bdh1. Both synthetic acetoin and 2,3-butanediol are able to enhance plant growth when supplied to plants. Transgenic Arabidopsis plants were generated which over-express the AlDc and Bdh1 genes, either singly or in combination. The AlDC and double transgenic plants showed considerably enhanced biomass production when compared with the control wild type plants. The Bdh1 single transgenics, which lacked acetoin as precursor for 2,3-butanediol synthesis, remained comparable in size to the control plants.

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Lucy Moleleki, E-mail: lucy.moleleki@up.ac.za Transcriptome profiling of long noncoding RNAs involved in potato responses to Pectobacterium spp S Kwenda1, V Gorshkov2, E Rubagotti3, G Mosina1, P Birch4 and LN Moleleki1 1Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa 2 Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia 2Department of Botany and Plant Physiology, Kazan Federal University, Kazan, Russia 3Genomics Research Institute, Centre for Microbial Ecology and Genomics (CMEG), University of Pretoria, Pretoria, South Africa

4Division of Plant Sciences, College of Life Sciences, (The James Hutton Institute), University of Dundee, Dundee, Scotland, UK Potato plants are susceptible to infection by soft rot enterobacteriaceae (SRE) resulting in blackleg and soft rot diseases, however, some cultivars exhibit varying degrees of tolerance. In South Africa, Pectobacterium carotovorum subsp. brasiliense (Pcb) has emerged as the most aggressive SRE infecting potato plants and causing major economic losses. There are currently no chemical control options available for soft rot pathogens. In this study we investigate colonization patterns of Pcb in a tolerant compared to a susceptible potato stem cultivar. We observed that Pcb tends to localize in the xylem, especially in the tolerant cultivar, where it forms biofilm like aggregates that occlude tissue. The xylem is a nutrient deficient environment, hence, to understand survival mechanisms used by Pectobacterium spp in such environments, we used strand specific RNASeq. Several sRNAs were identified and shown to play an important role in adaptive strategies of Pectobacterium spp under starvation conditions. We were also interested in understand important host response mechanisms, particularly focusing on differential responses between a tolerant and a susceptible potato cultivar. In this respect, ssRNAseq and transcriptome profiling identified several long noncoding RNAs (lncRNAs) that are differentially expressed between the two cultivars. lncRNAs are known to function as important regulators in plant gene regulatory networks modulating plant responses to stress and pathogen infections.

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Arun Gokul, E-mail: agokul5@gmail.com 3,3-Diindolylmethane mediated signaling and its role in Brassica napus L seedling response to vanadium stress A Gokul, M Keyster Environmental Biotechnology Laboratory, Department of Biotechnology, University of the Western Cape, Robert Sobukwe Road, Bellville 7530, South Africa South Africa (SA) is experiencing an influx in heavy metals into soils and ground water due to activities such as increased mineral mining, improper watering practices and the use of heavy metal contaminated fertilizers. These heavy metals lead to increase in reactive oxygen species (ROS) within plants, which may result in plant metabolism deterioration and tissue damage. SA is one of the number one producers of vanadium worldwide therefore it was selected as the metal of choice for this study. A secondary metabolite, 3, 3 Diindolylmethane (DIM), is suggested to enhance plant growth under normal circumstances. However, little research has been done using DIM as a mediator in abiotic stress responses. Preliminary results of this study have shown that exogenous application of DIM promotes growth of Brassica napus L (AV Garnet) and displays the potential to alleviate the effects of vanadium stress. Damage was observed to be reduced in the vanadium and DIM combination treated plants when compared to vanadium only treated plants. Therefore, we propose DIM as an important novel signalling molecule in controlling B. napus responses to vanadium stress.

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Antje Heese, Email: heesea@missouri.edu Role of vesicular trafficking proteins in plant innate immune responses against bacterial pathogens A Heese, C Collins, G Ekanayake, E LaMontagne, M Leslie, J Smith

Division of Biochemistry and Interdisciplinary Plant Group, 117 Schweitzer Hall, University of Missouri, Columbia, Missouri 65211, USA The plasma membrane (PM) serves as a crucial contact point for plant cells to perceive abiotic and biotic stresses. Plant proteins at this location are required for many aspects of signal perception, initiation and transduction of such diverse responses. A complex and dynamic vesicular trafficking network (including secretion and endocytosis) is essential to ensure the correct localization and level of plant components at the PM necessary for effective responses. Our lab utilizes the Arabidopsis plasma membrane-localized receptor Flagellin-Sensing 2 (FLS2)-bacterial flg22 model system to examine roles of vesicular trafficking in biotic responses. We have evidence that FLS2 needs to be localized to the PM in the correct abundance at the right time to perceive its ligand flg22 and initiate a robust immune response. However, few vesicular trafficking components are known with roles in FLS2 trafficking to and from the PM. Using a combination of biochemical, phosphoproteomics, genetics, pathological and live-cell imaging assays, we identified vesicular trafficking proteins with novel roles in flg22-signaling, FLS2 localization and immunity against pathogenic bacteria. One of these is an ENTH-domain containing protein, which functions in clathrin-mediated vesicle formation at the Trans-Golgi Network (TGN), potentially for delivery of newly synthesized cargo proteins to the vacuole or PM. Two independent enth mutant alleles showed defects in all investigated flg22-response and were more susceptible to infection by bacterial Pseudomonas syringae pv. tomato strains. Utilizing a simplified PM-enrichment and live-cell imaging methods, we correlated impaired flg22-signaling to reduced FLS2 protein levels at the PM. Our data identified this vesicular trafficking ENTH-protein as a novel positive regulator of innate immunity with roles in regulating correct FLS2 abundance at the PM. Our work has implications beyond plant innate immunity because we have preliminary evidence that ENTH and several other vesicular trafficking proteins have roles in abiotic responses including nutrient uptake.

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David Mendoza-Cozatl, E-mail: mendozacozatld@missouri.edu Molecular mechanisms of phloem transport and seed loading of heavy metals D Mendoza-Cozatl, S McInturf, M Khan Division of Plant Sciences and Interdisciplinary Plant Group, C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211, USA Plants and seeds are the main dietary source of essential micronutrients (Zn, Fe, Cu, Mn) but also the main entry point for toxic elements (Cd, Pb, As) into the food chain1. Our lab has two main focus areas: (i) the identification and characterization of phloem-loading transporters, which are key to understand how molecules are mobilized from leaves to seeds and (ii) the transcriptional responses mediating trace metal homeostasis, including responses to micronutrient deficiencies. We are using a combination of cell-specific transcriptomics, functional genomics and ionomics to understand how plants take up, distribute and accumulate micronutrients and toxic elements within plant tissues, including seeds. Using a companion cell ribo-seq approach, we have identified ≈75 Arabidopsis transporters preferentially expressed in phloem-loading cells (companion cells). We have cloned these transporters and assembled a functional expression library using yeast as heterologous expression system. Initial screens have identified transporters that induce hypersensitivity to cadmium or arsenic. Growth-based assays using yeast deficient in iron uptake suggest some transporters may mobilize iron into yeast. We are also characterizing plants carrying T-DNA insertions in phloem transporters. Using a recently described mutant (opt3-2) that over accumulates cadmium in seeds2, we have identified a transporter that suppresses the Cd sensitivity and over-accumulation of cadmium in opt3-2. Understanding the mechanisms that mediate trace metal accumulation in plants will help developing crops with higher nutritional value and minimal accumulation of non-essential elements such as cadmium and arsenic in edible tissues. 1. Khan et al. (2014) Front Plant Sci 5: 51 2. Mendoza-Cozatl et al. (2014) Mol Plant 7: 1455

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Ndiko Ludidi, E-mail: nludidi@uwc.ac.za Inhibition of nitric oxide synthase activity alters antioxidant activity in Vicia faba M Nkomo1,3, A Gokul2, A Klein3, I Egbichi4, M Keyster2, N Ludidi1

1Plant Biotechnology Research Group, Department of Biotechnology, University of the Western Cape, Robert Sobukwe Road, Bellville 7530, South Africa 2Environmental Biotechnology Laboratory, Department of Biotechnology, University of the Western Cape, Robert Sobukwe Road, Bellville 7530, South Africa 3Proteomics Research Unit, Department of Biotechnology, University of the Western Cape, Robert Sobukwe Road, Bellville 7530, South Africa 4Department of Biological and Environmental Sciences, Private Bag X1, Walter Sisulu University, Mthatha, 5100, South Africa Nitric oxide (NO˙) is a signaling molecule synthesized mainly by nitric oxide synthase (NOS) and nitrate reductase (NR) enzymatic activities in plants. Although the encoding gene and the protein responsible for NOS activity has not been identified in any higher plant species, the enzymatic activity has been detected in a number of plant species. Furthermore, use of a specific competitive inhibitor of mammalian NOS activity [namely Nω-Nitro-L-arginine methyl ester (L-NAME)] leads to inhibition of plant NOS enzymatic activity and a decline in plant nitric oxide content. Nitric oxide is involved in the regulation of reactive oxygen species (ROS) via modulation of the activities of enzymes involved in reactive oxygen species metabolism. We thus investigated the effect of NOS inhibition by L-NAME on NO˙ content, antioxidant enzyme activities, H2O2, malondialdehyde (MDA, as an indicator of lipid peroxidation), glycine betaine and proline contents along with cell viability in Vicia faba (broad bean). Inhibition of NOS activity reduced Vicia faba NO˙ content and altered the activities of superoxide dismutase, ascorbate peroxidase and catalase. NOS inhibition resulted in elevation of H2O2 content, reduction of glycine betaine and proline contents, increase in MDA content and reduction of cell viability in Vicia faba. The results show that NOS activity regulates antioxidant capacity and levels of amino acids/amino acid derivatives implicated in ROS scavenging and this influences ROS accumulation and cell death. These results have implications on ROS-regulated plant responses such as responses to abiotic stress.

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Lara Donaldson, E-mail: lara.donaldson@uct.ac.za Transcriptomic analysis of the response of Arabidopsis to the ionic and osmotic components of salinity stress L Donaldson Department of Molecular and Cell Biology, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa Salinity and drought stresses are intrinsically linked because salinity reduces the plants ability to take up water thereby imposing drought (osmotic) stress while drought leads to soil salinization. Salinity and drought are the leading environmental factors reducing crop productivity and threatening food security. In order to feed the growing population, stress tolerant crops must be developed. The limited success to date, in bringing salinity and drought tolerant crops to the field, has been blamed on the inadequate identification of genes involved in the plant’s response to salinity and drought stress. Historically, transcriptomics experiments to identify these genes have measured short-term responses to salt shock which results in plasmolysis and ultimately death; and does not allow time for Na+ ions to accumulate in the plant. It is not surprising then that these experiments have failed to identify genes involved in salinity tolerance. To address this short-falling we have germinated and grown Arabidopsis seedlings on physiologically relevant, low concentrations of NaCl and isoosmolar osmotic stress and performed global transcriptome analysis. Differentially expressed gene lists have been compared to identify genes that are responsive to the ionic and osmotic components of salt stress. We are now investigating several candidate genes that can be combined to engineer crop plants with enhanced expression of multiple mechanisms for tolerating salinity and drought stress.

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Eugene Makgopa, E-mail: eugene.makgopa@up.ac.za Ectopic expression of a phytocystatin, oryzacystatin-I (OCI) leads to enhanced drought tolerance in soybean ME Makgopa Plant Biotechnology Research Group, Department of Plant Science, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa Drought stress accounts for about 40% of crop yield losses. It is there important to develop crop varieties with enhanced environmental stress tolerance traits. In legumes, drought causes early senescence due to loss of the symbiotic relationship between the plant and the nitrogen-fixing bacteria. Senescence is characterized by increases in proteolytic enzymes involved in various processes in the plant’s responses to stress. Here the effects of expression of the rice cystatin, oryzacystatin-I (OCI), on the growth, development and stress tolerance of soybean crop plants were characterized. Plants of transgenic soybean lines had differential transgene expression. Transgenic plants had lower protease activity determined by an in-gel assay using SDS-PAGE. Seeds of different transgenic soybean lines had a lower germination rate and these transgenic lines had fewer leaves and shorter stems. Ectopic OCI expression in soybean enhanced leaf chlorophyll accumulation at later stages of vegetative development. Under drought stress, plants of transgenic lines performed better CO2 assimilation (photosynthesis) and instantaneous water-use efficiencies (IWUE) than wild-type non-transgenic plants. Results obtained in this study have provided evidence that preventing cysteine protease activity by over-expressing a protease inhibitor causes phenotypic changes of the plant demonstrating an important role of cysteine proteases in plant growth and development and plant stress.

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Felix B Fritschi, E-mail: fritschif@missouri.edu Leveraging natural genetic variation to increase soybean yields in water-limited environments FB Fritschi Division of Plant Sciences and Interdisciplinary Plant Group, University of Missouri, Columbia, Missouri 65211, USA Water deficit stress is one of the most important yield limiting factors for soybean (Glycine max L.). Breeding efforts to improve soybean yields and/or yield stability in environments with limited water availability have mainly focused on shoot traits while neglecting root characteristics. As the imposition of drought stress can differ dramatically among years, locations, and based on soil types, whole-plant responses including shoot and root specific traits as well as root-shoot and shoot-root signals need to be considered to optimize yields for distinct environments. Available collections of soybean genotypes encompass tremendous natural variation among the entries that can be explored to identify genotypes with traits of interest for crop improvement. Therefore, we have initiated research aimed at identifying soybean germplasm contrasting for shoot and root based traits that can be leveraged for in-depth physiological studies, dissection of their genetic basis, and in breeding efforts. The core traits of interest include water use efficiency, symbiotic nitrogen fixation, and root architectural characteristics. We are using new and established methods for high-throughput phenotyping of these traits under field conditions. Our efforts have led to the identification of genetic markers, physiological analyses using contrasting genotypes, and are broadening the genetic basis of breeding programs.

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Jill M. Farrant, E-mail: jill.farrat@uct.ac.za Resurrection plants as models for understanding of what is required for extreme drought tolerance JM Farrant Department of Molecular and Cell Biology, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa Drought is one of the greatest threats to world agriculture and it is predicted that the effects of climate change will cause desertification in South Africa and many areas of the world over the next 35 years. To safeguard food production, it is essential to improve drought tolerance in crops. To date this has not been achieved, because vegetative tissues of crops do not tolerate much water loss, survival being contingent on mechanisms that retain water (technically drought resistance) and the production of dry desiccation tolerant seeds which survive conditions unfavourable for vegetative growth. While attempts have been made to improve resistance characteristics in crops, such mechanisms fail under severe drought. Little effort has yet been made to include tolerance characteristics, as there are few plants that do tolerate extreme water loss that could be used as models for understanding what such characteristics entail. There are however, some 135 angiosperm species, most occurring in Southern Africa, that tolerate loss of 95% of cellular water for prolonged periods without dying. Termed resurrection plants such species are not only desiccation tolerant but survive extreme heat; conditions which severely limit current agricultural practices. Our group has systematically investigated the mechanisms whereby several different resurrection plants tolerate these extreme conditions, with the view of introducing such characteristics into crops for true drought tolerance and ultimately food security in the face of climate change. In this presentation an overview of some of the molecular and physiological processes associated with tolerance of extreme water loss in a range of resurrection plants will be given.

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Nokwanda (Nox) Makunga, E-mail: makunga@sun.ac.za Understanding chemical diversity in plants used for medicinal purposes in the Cape NP Makunga Department of Botany and Zoology, Stellenbosch University, Merriman Avenue, Stellenbosch 7600, South Africa South Africa is blessed with an incredibly diverse floral heritage that forms the basis for medicinal use by local people. An understanding of the environmental impacts on plants that are traditionally used for medicinal purposes is thus important as this impacts chemical diversity and subsequently bioactivity. Several medicinal plants that are part of KhoiSan herbalism are studied in our environment. We use a multidirectional approach that is able to inform us on the effects of the growth environment on metabolomics and pharmacology linked to wild populations and those plants grown in vitro. Our work on Sutherlandia frutescens illustrates population differences that are associated with various geographic locations that are linked to flavonoid and terpenoid metabolism. Using a bioengineering approach, hairy root clones could easily be distinguished from transgenic shoots as they cluster based on sutherlandins. A strategy that is opportune for producing mesembrine-yielding lines has potential as a manufacturing platform to assist with conservation of Sceletium. Finally, reesarch on chemotherapeutic anticancer agent identifies genomic-metabolomic approaches an important element of clarifying population structure from various plants growing in the greater Cape Floristic Region.

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Walter Gassmann, E-mail: gassmannw@missouri.edu Striking a balance: functions of the Arabidopsis immune adaptor protein SRFR1 SH Kim1, GH Son1,2, S Bhattacharjee1, HJ Kim2, JC Nam1, PDT Nguyen1, JC Hong1,2, W Gassmann1

1Division of Plant Sciences and Interdisciplinary Plant Group, CS Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211, USA 2Biochemistry Department, Division of Life Science, Gyeongsang National University, Jinju, Gyeongnam 660-701, Republic of Korea Plant immunity needs to be tightly controlled both positively and negatively to enable normal plant growth, because constitutively activated defense responses are detrimental to the host. How plants achieve this balance is not fully understood. In previous work, we reported that mutations in SRFR1 (SUPPRESSOR of rps4-RLD1), identified in a suppressor screen, reactivated avrRps4-triggered immunity in rps4 mutant plants. Resistance in srfr1 mutants was not effective against virulent bacterial pathogens, suggesting that SRFR1 is a specific negative regulator of effector-triggered immunity. Interestingly, SRFR1 and EDS1 interact in planta, and this protein complex is targeted by the effectors AvrRps4 and HopA1. SRFR1 encodes a pioneer tetratricopeptide repeat (TPR) protein conserved between plants and animals. The SRFR1 TPR domain has significant sequence similarity to those of the Saccharomyces cerevisiae Ssn6 and Caenorhabditis elegans OGT (O-linked N-acetylglucosamine transferase) proteins, which function as transcriptional repressors. A functional sub-pool of SRFR1 localizes to the nucleus, and we recently showed that SRFR1 interacts with members of the TCP transcription factor family. Given that TCP transcription factors mainly regulate developmental processes, we propose that nuclear SRFR1 functions in a transcriptional repressor complex that balances plant immunity and development.

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Marshall Keyster, E-mail: mkeyster@uwc.ac.za Effect of exogenous 3,3'-diindolylmethane (DIM) on Brassica napus seedlings A Gokul1, E Roode1, A Klein2, M Keyster1 1Environmental Biotechnology Laboratory, Department of Biotechnology, University of the Western Cape, Robert Sobukwe Road, Bellville 7530, South Africa 2Proteomics Research Unit, Department of Biotechnology, University of the Western Cape, Robert Sobukwe Road, Bellville 7530, South Africa Brassica napus L. (cv. AV Garnet) seeds were pre-treated with 15 μM 3,3'-diindolylmethane (DIM) to investigate whether DIM could enhance seed germination. Further treatment of seedlings with 15 μM DIM for 14 days explored the effects on seedling growth. Exogenous DIM led to improved germination percentage, increased seedling lengths and increased fresh and dry weights. Furthermore, DIM triggered induction of superoxide radical (O2

-) and hydrogen peroxide (H2O2) content however, no change in malondialdehyde (MDA) content and cell death (assessed with Evans Blue assay) was detected for both the control and DIM treated seedlings. We also observed increases in superoxide dismutase (SOD) activity and ascorbate peroxidase (APX) activity in response to exogenous DIM, two fundamental enzymes in the control of reactive oxygen species (ROS) in plants. Our results indicate that exogenous DIM treatment enhances seed germination and improves seedling growth through possible activation of a reactive oxygen species signalling pathway involving O2

- and H2O2 in B. napus.

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Isaiah Taylor, Email: iwtwb8@mail.missouri.edu A series of genetic suppressors suggests complex regulation of floral organ abscission in Arabidopsis I Taylor, J Baer, JC Walker Division of Biological Sciences and Interdisciplinary Plant Group, University of Missouri, Columbia, MO 65211, USA In Arabidopsis, floral organ shedding, or abscission, occurs rapidly following pollination. A central signaling pathway controlling organ abscission is mediated by two paralogous leucine-rich repeat receptor-like protein kinase (LRR-RLK) genes HAESA and HAESA-like 2 (HAE/HSL2). Double mutant plants of HAE/HSL2 are completely defective in abscission and retain sepals, petals, and stamen indefinitely. To identify other genes that regulate abscission, we carried out multiple suppressor screens of an abscission deficient hae hsl2 mutant. From these screens, we isolated 5 lines with semi-dominant point mutations in the SERK1 LRR-RLK gene exhibiting restored abscission. SERK1 encodes a well-studied member of the SERK family of co-receptor receptor-protein kinases implicated in a number of developmental and pathogen response signaling pathways. In vitro autophosphorylation assays demonstrate the isolated mutants possess a functional protein kinase domain. Furthermore, a previously characterized loss of function allele of SERK1 is unable to suppress hae hsl2, indicating the ability to suppress hae hsl2 is a specific effect of the mutations identified in our screens. Mapping of the mutations onto solved crystal structures of SERK1 or the closely related protein BAK1/SERK3 shows 4 of the mutations cluster to a spatially restricted region of the SERK1 kinase domain, while the 5th maps closely to a residue known to induce conditional hyperactivity when mutated. Taken together, these results suggest there is a HAE/HSL2 independent signaling pathway activated in these mutants, possibly through hyperactivation of SERK1. These mutants will inform our understanding of abscission, as well as SERK1 activity, an important general signaling regulator.

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Julian May, Email: jmay@uwc.ac.za The DST-NRF CoE in Food Security: Role and opportunities J May The DST-NRF Centre of Excellence in Food Security, University of the Western Cape, Bellville, South Africa

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Paula McSteen, E-mail: mcsteenp@missouri.edu Inflorescence development in maize P McSteen

Division of Biological Sciences and Interdisciplinary Plant Group, University of Missouri, 371f Bond Life Sciences Center, 1201 Rollins Street, Columbia, Missouri 65211, USA Maize produces two types of inflorescence – the male inflorescence or tassel, which produces the pollen, and the female inflorescence or ear, which produces the kernels and is harvested. Maximization of yield potential requires an understanding of the development of the inflorescence, and in particular the activity of meristems within the inflorescence. The length of the inflorescence is determined in part by the activity of the apical inflorescence meristem, while the branches, spikelets, florets, and ultimately kernels, arise from axillary meristems on the flanks of the apical inflorescence meristem. We are using a genetic approach to determine the mechanisms regulating inflorescence development in maize by identifying mutants. One class of mutants has defects in the biosynthesis, transport or response to the plant growth hormone, auxin, implicating auxin in the process of axillary meristem initiation and spikelet production. This class of mutant often produces no ear shoot, indicating that auxin is also required for the initiation of the ear in maize. Another class of mutants has defects in nutrient metabolism, implicating essential micronutrients in the maintenance of the apical meristem and hence ear size. Identification of the genes defective in these mutants and dissection of their function is shedding light on the mechanism of inflorescence development, which is essential for efforts to sustain and improve yield in all cereals.

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Kyle Phillips, E-mail: kphil0803@gmail.com A novel Zea mays BURP domain-containing gene is involved in the regulation of maize drought response K Phillips, N Ludidi Plant Biotechnology Research Group, Department of Biotechnology, University of the Western Cape, Robert Sobukwe Road, Bellville 7530, South Africa Global climate change has resulted in altered rainfall patterns, causing annual losses in maize crop yield due to drought. Therefore, it is important to produce maize cultivars that are more drought-tolerant, which is not an easily accomplished task as plants have a plethora of physical and biochemical adaptation methods. One such mechanism is the drought-induced expression of enzymatic and non-enzymatic proteins which assist plants to resist the effects of drought on their growth and development. One such protein is AtRD22, which has been identified in Arabidopsis thaliana. Using an in silico approach, a maize protein with 48% sequence homology to AtRD22 has been identified. This protein appears to be localized in the extracellular matrix, similar to AtRD22. Promoter analysis of the gene reveals cis-acting elements suggestive of induction of the gene’s expression by abscisic acid (ABA). Semi-quantitative and quantitative transcriptomic analysis of the putative maize RD22 gene reveals an increase in transcript levels after exposure to drought and ABA treatment. Current work elucidates the effect of up-regulation and silencing of the maize RD22 gene on the tolerance of maize to drought.

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Jacob D. Washburn, E-mail: jdwr47@mail.missouri.edu Comparative phylogenomic methods for systematics, taxonomy, and evolutionary studies: an example from the grass tribe Paniceae and C4 photosynthetic evolution J Washburn, JC Pires Division of Biological Sciences and Interdisciplinary Plant Group, University of Missouri, 311 Bond Life Sciences Center, Columbia, Missouri 65211, USA Molecular phylogenetics has been an important part of systematics and taxonomy for several decades. However, with the improvement of DNA and RNA sequencing technologies a paradigm shift is occurring within the field. Where researchers once spent many months choosing the “right” gene for sequencing and phylogenetic study, it is becoming ever more common to simply sequence large numbers of genes and then bioinformatically determine which ones are best for phylogenetic inference. These cost and time effective methods also allow inexpensive first pass identification of specimens prior to investing large amounts of time and specialized training into morphological identification. Beyond phylogenetics and taxonomy, these data can also be used to answer both basic and applied biological questions. As an example, we demonstrate the usefulness and methods of comparative phylogenomics in resolving the phylogeny of the grass tribe Paniceae (Poaceae) and dissecting the evolution of C4 photosynthesis, an economically and scientifically important trait.

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Ashwil Klein, E-mail: aklein@uwc.ac.za Biochemical responses of two chia (Salvia hispanica L.) genotypes to salt stress S Jones, A Williams, M Nkomo, A Klein Proteomics Research Unit, Department of Biotechnology, University of the Western Cape, Robert Sobukwe Road, Bellville 7530, South Africa The objective of this study is to investigate the effect of long term (21 days) salt stress (100 mM NaCl) on oxidative damage caused by ROS accumulation, lipid peroxidation and antioxidant capacity in two chia genotypes under controlled environmental conditions. The results showed that the Tzotzol genotype experience more oxidative damage than the Iztac genotype when exposed to salt stress, which corresponded to higher levels of O2

-, H2O2 and MDA being produced. The increase in ROS scavenging enzyme activities in response to salt stress was weaker in the Tzotzol genotype than the Iztac genotype. As a consequence, the higher levels of oxidative damage in the Tzotzol genotype in response to salt stress was verified by an increased level of cell death when compared to the Iztac genotype. This data suggest a direct relationship between salt stress-induced oxidative damage and cell death and that salt stress tolerance is dependent on efficient antioxidant scavenging to reduce oxidative damage therefore limiting cell death as observed in the Iztac genotype.

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Scott Peck, E-mail: pecks@missouri.edu Using proteomics to study signaling and secretion during responses to biotic and abiotic stresses SC Peck Division of Biochemistry and Interdisciplinary Plant Group, 271H Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211, USA Plants perceive potential pathogens by recognizing pathogen-associated molecular patterns (PAMPs) through plasma membrane (PM) receptors. Recognition of flg22, a 22 amino acid PAMP derived from the bacterial flagellum, by the receptor-like kinase FLS2 induces defense signaling responses and contributes to innate immunity by restricting bacterial invasion. Quantitative phosphoproteomic analyses of Arabidopsis proteins following PAMP treatments identified numerous candidates for components of the signal transduction machinery. Reverse genetic investigations of these differentially phosphorylated proteins has revealed functions for a number of these candidates in innate immune responses. Using kinase-substrate pairs we identified during these studies, we have also demonstrated the efficacy of using bioinformatic predictions to identify additional components of kinase signalling pathways. The plasma membrane (PM) is the interface between a cell and its environment. Therefore, PM proteins play an important role in integrating a cell’s responses to biotic and abiotic stresses. To simplify analyses of PM proteomes, we have developed a simple and widely applicable strategy for enriching for PM proteins; and we have used this technique to examine changes in the PM proteome of Arabidopsis during innate immune responses and in primary maize roots during low water potential (i.e. drought). The technical strategy as well as some of our recent findings will be discussed.

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LIST OF DELEGATES 1. Bastian, R (Delegate, Department of Agriculture, Western Cape Government) 2. Bharuthram, R (Executive: Special Projects, UWC) 3. Braun, D (Delegate, MU) 4. Davies-Coleman, M (Dean: Faculty of Natural Sciences, UWC) 5. Donaldson, L (Delegate, UCT) 6. Durbak, A (Delegate, MU) 7. Farrant , J (Deligate, UCT) 8. Fritschi, F (Deligate, MU) 9. Gassmann, W (Delegate, MU) 10. Gokul, A (Delegate, Organizing Committee: UWC) 11. Heese, A (Delegate, MU) 12. Hills, P (Delegate, SU) 13. Ingle, R (Delegate, UCT) 14. Keyster, M (Delegate, Organizing Committee: UWC) 15. Klein, A (Delegate, Organizing Committee: UWC) 16. Lawack, V (Deputy Vice-Chancellor: Academic, UWC) 17. Ludidi, N (Delegate, Organizing Committee: UWC) 18. Makgopa, E (Delegate, UP) 19. Makunga, N (Delegate, SU) 20. Masehela, T (Delegate, Kirstenbosch Botanical Gardens, SANBI) 21. May, J (Delegate, Organizing Committee: UWC; Director: DST-NRF CoE in Food Security) 22. McSteen, P (Delegate, MU) 23. Mendoza-Cozatl, D (Deligate, MU) 24. Modise, J (Delegate, Department of Agriculture, Western Cape Government) 25. Moleleki, L (Delegate, UP) 26. Murray, S (Delegate, UCT) 27. Ndimba, B (Delegate, Agricultural Research Council) 28. Oliver, M (Delegate, MU) 29. Peck, S (Delegate, MU) 30. Phillips, K (Delegate, UWC) 31. Rafudeen, S (Delegate, UCT) 32. Rohwer, J (Delegate, SU) 33. Sharp, R (Delegate, Organizing Committee, MU) 34. Slabbert, S (Delegate, Department of Agriculture, Western Cape Government) 35. Swanepoel, F (Deputy Vice-Chancellor: Research and Innovation, UWC) 36. Taylor, T (Delegate, MU) 37. Uphoff, R (Director: University of Missouri South African Education Program, MU) 38. Washburn, J (Delegate, MU)

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