PRESENTATION: Inheritance of rootstock effects in avocado ... · Inheritance of rootstock effects...

Inheritance of rootstock effects

in avocado cv. Hass

Paula Reyes, Andrés J. Cortés, Laura Muñoz, Valeria Velázquez, Laura Patiño, Oscar Delgado, Cipriano Díaz,

Alejandro Navas

[email protected]

Warschefsky et al. 2015

Grafting: Rootstock – Scion Interaction

environment in which the grafted plant will be grown [47]; and (v) rootstocks are selected not onlyfor traits inherent in the root system but also for traits imparted to the scion (Figure 1, Key Figure).

For example, the introduction of the North American aphid Phylloxera into Europe in the mid-1800s devastated the grape (Vitis vinifera) industry on the European continent [48]. GraftingV. vinifera scions onto Phylloxera-resistant rootstocks allowed V. vinifera to grow in the presenceof Phylloxera and today grafting is commonplace in grape, with native North American grapevinespecies functioning as indispensable resources for the development of abiotic and biotic stress-resistant rootstocks [49,50]. Vitis riparia and Vitis rupestris were initially selected for Phylloxera

Key Figure

Primary Targets of Rootstock Selection

Gra!ingSelec"on

Gra!ed domes"catedscion

Gra! compa"bilityGra!ed domes"catedrootstock

Own-rooteddomes"cated rootstock

Own-rootedrootstock wild rela"ve

Ease of vegeta"vepropaga"on

Root pest/pathogenresistance

Abio"c stress tolerance(drought, flooding, salt, soil condi"ons)

Dwarfing Precocity Produc"vity (flowering, fruit set,fruit weight, overall yield)

Cold toleranceShoot pest/pathogenresistance

Fruit quality (texture, sugar and nutrientcontent, weight, acidity, pH, flavor, and color)

(A)

(C)

(D)

(B)

Figure 1. Rootstocks used in perennial agriculture (A) have been selected from a pool of wild germplasm and bred for (B)their ability to graft to cultivated scions, (C) the root phenotype, and (D) their ability to impact the phenotype of the graftedscion.

Trends in Plant Science, May 2016, Vol. 21, No. 5 425

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Key Figure


Gra!ingSelec"on











(A)

(C)

(D)

(B)





Key Figure


Gra!ingSelec"on











(A)

(C)

(D)

(B)








Key Figure


Gra!ingSelec"on











(A)

(C)

(D)

(B)





Key Figure


Gra!ingSelec"on











(A)

(C)

(D)

(B)





Key Figure


Gra!ingSelec"on











(A)

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HORTSCIENCE 54(5):809–813. 2019. https://doi.org/10.21273/HORTSCI13552-18

Screening Progenies of Mexican RaceAvocado Genotypes for Resistance toPhytophthora cinnamomi RandsEnrique I. S!anchez-Gonz!alez, J. Guadalupe Guti!errez-Soto,Emilio Olivares-S!aenz, and Adriana Guti!errez-Díez1Universidad Aut!onoma de Nuevo Le!on, Facultad de Agronomía, GeneralEscobedo, Nuevo Le!on, 66059 Mexico

Alejandro F. Barrientos-PriegoUniversidad Aut!onoma Chapingo, Departamento de Fitotecnia, Chapingo,Estado de Mexico, 56230 Mexico

Salvador Ochoa-AscencioUniversidad Michoacana de San Nicol!as de Hidalgo, Facultad deAgrobiología Presidente Ju!arez, Uruapan, Michoac!an, 60170 Mexico

Additional index words. Persea americana, var. drymifolia, genetic resistance, phytophthoraroot rot

Abstract. Because of the low availability of avocado rootstocks with resistance toPhytophthora cinnamomi, it is necessary to search for genotypes that offer resistance andthat could be used as commercial rootstocks. The objective of this study was to selectprogeny from the genotypes of Mexican race avocado plants that are resistant toP. cinnamomi. Seedlings from 12 avocado genotypes were placed in containers inoculatedwith a mycelial suspension of P. cinnamomi. Signs of disease in the upper part of theseedlings were registered every 3 days for 8 weeks using a visual scale of damage severity.The x2 test (P < 0.009) showed significant differences among the genotypes evaluated,with ‘Todo el Ano’ being the most resistant, as demonstrated by its rating of 70%asymptomatic seedlings, followed by ‘Pl!atano’ with 40%. Themost susceptible genotypeswere ‘María Elena’, ‘Silvestre’, and ‘Hass’, with 100% mortality. Seedling inoculationfacilitated the detection of resistance to P. cinnamomi. ‘Todo el Ano’ showed resistancetoward P. cinnamomi. Therefore, individuals of its offspring could be recommended foruse as rootstocks after confirming their resistance with a second evaluation, as well asperforming tests in multiple localities to demonstrate their productive behavior aftergrafting.

The main disease affecting avocado pro-duction systems worldwide is phytophthoraroot rot caused by Phytophthora cinnamomiRands (Hardham, 2005). This disease hasbeen reported to infect avocado in !70countries (Pegg et al., 2002), and in Mexicoit is one of the main limitations for avocadoproduction. P. cinnamomi can affect seed-lings of any age, causing root damage,

which leads to secondary symptom devel-opment in the upper part of the plant. Thesesymptoms include dieback of the branches,yellowing and wilted leaves, complete de-foliation, and tree death, reducing theamount of production and the area culti-vated (Andrade-Hoyos et al., 2015; Rodrí-guez, 2015). The pathogen forms resistancestructures called chlamydospores that cansurvive for long periods in soil even with-out a host, making its eradication difficultonce the disease has become established(Andrade-Hoyos et al., 2015). Controlmethods for this pathogen are chemicaland biological, and the use of good culturalpractices. However, they present somelimitations, and the implementation ofmore sustainable control methods is nec-essary. An alternative to these methods isto use rootstocks resistant to P. cinna-momi, although after decades of research,few materials with a moderate level ofresistance have been selected.

From the three avocado races used asrootstock, the Mexican race (Persea ameri-cana Mill. var. drymifolia) has shown moretolerance and even moderate resistance to P.

cinnamomi (G!omez, 2014; S!anchez, 2007).Currently, different rootstocks are availablein the market that are characterized as beingmoderately resistant to P. cinnamomi, includ-ing ‘Barr Duke’, ‘Duke 6’, ‘Duke 7’, ‘Duke9’, ‘Thomas’, and ‘Toro Canyon’—all Mex-ican race avocado plants (Rodríguez, 2015).The use of rootstocks from var. drymifoliais the base of ‘Hass’ avocado production inthe principal cultivated areas in the world(Rinc!on-Hern!andez et al., 2011). As a resultof factors such as an increase in plantations inareas with inadequate drainage and irrigation(Reeksting et al., 2016), as well as limitedavailability of resistant rootstocks and theirlow adaptation to different soils and climates,it is necessary to search for genotypes thatpresent resistance to the pathogen and canbe used potentially as commercial root-stocks. Some options are to use the geneticbasis of P. americana var. drymifolia, searchthe existing germplasm banks in the coun-try, and scrutinize wild materials (genotypesthat are naturally present in a forest envi-ronment) for their wide genetic diversity.

Methods used to determine the resistanceof P. americana to P. cinnamomi began inthe 1950s with the investigations of Dr.Zentmyer and his laboratory at the Univer-sity of California, Riverside, CA, with materialscollected in different countries of Latin America(Zentmyer and Schieber, 1987, 1992). The re-sistance of avocado to P. cinnamomi has beendetermined through different methods, includ-ing the use of nutritive solutions with infectivematerial (zoospores and mycelia), pots andgerminating beds with infested soil, in vitrocultures for the inoculation of the callus, tests ininfested fields, and changes in the electricalconductivity of inoculated root fragment sus-pensions (Salgado and Fucikovsky, 1996).

The search for genotypes resistant to P.cinnamomi by scrutinizing seedlings of seed orclonal origin has enabled the identification ofindividuals resistant to P. cinnamomi withpotential use as clonal rootstocks (Andrade,2012; Casta~neda, 2009; Douhan et al., 2011;Ploetz et al., 2002), the identification of parentsthat produce high proportions of resistant prog-eny, and the determination of the broad-senseheritability of this trait (Ploetz et al., 2002).

Thus, the objective of our work was toevaluate progenies from 10 Mexican raceavocado genotypes from the south of NuevoLeon State, Mexico, to find resistance to P.cinnamomi.

Materials and Methods

Our study was conducted during Summer2017 at the Agronomy School of Universi-dad Aut!onoma de Nuevo Le!on in Mexico.Ten genotypes of Mexican race avocado—‘Todo el A~no’, Pl!atano Delgado’, ‘Bola’,‘Leonor’, ‘Pl!atano’, ‘Pl!atano Temprano’,‘Silvestre’, ‘María Elena’, ‘Criollo 3’, and‘Criollo 6’—from the municipalities ofAramberri and General Zaragoza in NuevoLe!on, Mexico, were evaluated for their re-sistance to P. cinnamomi. The ‘Hass’ geno-type (Mexican race · Guatemala race, from

Received for publication 6 Sept. 2018. Acceptedfor publication 15 Mar. 2019.This paper is part of the Master of Science thesis ofE.I. S!anchez-Gonz!alez.Research was conducted at the Biotechnology andNatural Sciences Laboratories of the Facultad deAgronomía, Universidad Aut!onoma de NuevoLe!on, Mexico.We thank Consejo Nacional de Ciencia y Tecno-logía de Mexico, the Committee of Science andTechnology in Mexico, for sponsoring E.I.S!anchez-Gonz!alez (scholarship no 431803) duringhis master studies.1Corresponding author. E-mail: [email protected] is an open access article distributed under theCC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/).

HORTSCIENCE VOL. 54(5) MAY 2019 809

Grafting: Rootstock – Scion Interaction R O O T S T O C K P R O P E R T I E S I N A V O C A D O

Effects of clonal rootstocks on ‘Hass’ avocado yield components,alternate bearing, and nutrition

By MICHAEL V. MICKELBART1,3*, GARY S. BENDER2, GUY W. WITNEY1,4, CAROL ADAMS5

and MARY LU ARPAIA1,6

1Department of Botany and Plant Sciences, University of California, Riverside, California 92521-0124, USA 2Cooperative Extension, University of California, 5555 Overland Avenue, San Diego, California92123, USA(e:mail: [email protected]) (Accepted 18 February 2007)

SUMMARYGrowth, yield, and leaf nutrient concentrations were measured in ‘Hass’ avocado (Persea americana Mill.) trees grownon one of ten clonally-propagated rootstocks (‘Borchard’, ‘D9’, ‘Duke 7’, G1033, G755A, G755B, G755C, ‘Thomas’,‘Topa Topa’, or ‘Toro Canyon’) over a 10-year period in southern California. After 10 years, trees on ‘Borchard’ werelarger than trees on all other rootstocks. Trees on all rootstocks displayed an alternate-bearing pattern, typical ofavocado. Alternate-bearing was most pronounced in trees grafted onto ‘Topa Topa’ and ‘Toro Canyon’. Rootstocks inthe G755 series had the lowest alternate-bearing index, but also had the lowest yields.Trees on ‘Duke 7’ and ‘Borchard’had the highest cumulative yields, and trees on G755A, G755B, and G755C had the lowest yields. Differences in yieldwere due to differences in the number of fruit per tree, not individual fruit weight. When yield was evaluated in termsof canopy efficiency (kg fruit m–3), no rootstock outperformed ‘Duke 7’, the industry standard rootstock. Leafconcentrations of all nutrients examined (N, P, K, Ca, Mg, S, Zn, Cl, Mn, B, Fe, and Cu) were within, or close to therecommended ranges. P, Ca, and S were higher, and Fe was lower in high-yielding years in all rootstocks.

Avocado (Persea americana Mill.) production inCalifornia tends to be low compared to other avocado-

producing regions worldwide (www.avocadosource.com).Furthermore, the costs of production are increasing inCalifornia (Takele et al., 2002). Therefore, any factor thatcan increase yield is of interest to California growers.

Until the mid-1970’s, avocado was propagated onseedling rootstocks. It was not until the mid-1970’s thatclonally produced rootstocks for avocado were madeavailable for commercial use (Ben Ya’acov andMichelson, 1995). Clonal avocado rootstocks have beenselected primarily on the basis of their resistance toavocado root rot (Phytophthora cinnamomi Rands.;Menge et al., 1992). Increasingly, avocado rootstocks arealso being selected on the basis of their salt tolerance(Mickelbart and Arpaia, 2002), especially in regions suchas Israel, Australia, and California. Ultimately, theserootstocks must also allow the full yield potential of thescion to be realised, although this is usually a secondaryscreen after material has been selected based on itsrelative tolerance to stress. There has been littleevaluation of avocado rootstocks in terms of their effectson yield and yield components.

Apart from yield per se, consistent annual yield is animportant consideration in avocado production. Annualproduction is subject to fluctuations caused by alternate-bearing patterns. Seasons in which high yields occur areusually followed by a yield decline of approx. 50%(Anon., 2005). Differences in crop volumes from year-to-year may result in the loss of revenue during low-yieldyears, and in oversupply during high-yield years.Therefore, it is important to screen avocado rootstocks,not simply for their effect on average annual yield, butalso for their effect on alternate-bearing. The goal of thislong-term study was to evaluate ten clonal avocadorootstocks for horticultural factors of interest to growers.

MATERIALS AND METHODSPlant material and field environment

‘Hass’ avocado was clonally propagated on one of tenrootstocks (G755A, G755B, G755C, G1033, ‘Duke 7’,‘Borchard’, ‘D9’, ‘Thomas’, ‘Toro Canyon’, or ‘TopaTopa’). Most trees were planted in April 1986 at theUniversity of California South Coast Research andExtension Center (SCREC) in Irvine, California (33°44’ N;117°49’ W). Trees on G1033 and ‘Thomas’ rootstockswere planted in April 1987, in pre-selected sites that wereincluded in the original experimental design.Twenty treesper rootstock were used for all measurements. The treeswere planted at a spacing of 6.1 m ! 6.1 m on slightlyraised, 1.5 m-wide by 0.5 m-high berms to facilitate waterdrainage. The soil type was a Hanford sandy loam(average depth 18 m), and the site was determined to befree of avocado root rot (P. cinnamomi Rands.). At the

*Author for correspondence.3Current Address: Department of Horticulture and

Landscape Architecture, Purdue University, 625 AgriculturalMall Drive, West Lafayette, IN 47907-2010, USA.

4Current address: California Avocado Commission, 1251 E.Dyer Rd. Suite 200, Santa Ana, CA, 92705-5631, USA.

5Biostatistician (deceased), Department of Statistics,University of California, Riverside, CA, 92521-0124, USA.

6Current address: Kearney Agricultural Center, 9240Riverbend Ave., Parlier, CA, 93648, USA.

Journal of Horticultural Science & Biotechnology (2007) 82 (3) 460–466

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Grafting: Rootstock – Scion Interaction R O O T S T O C K E F F E C T S I N A V O C A D O

Effects of clonal rootstocks on ‘Hass’ avocado yield components,alternate bearing, and nutrition

By MICHAEL V. MICKELBART1,3*, GARY S. BENDER2, GUY W. WITNEY1,4, CAROL ADAMS5

and MARY LU ARPAIA1,6

1Department of Botany and Plant Sciences, University of California, Riverside, California 92521-0124, USA 2Cooperative Extension, University of California, 5555 Overland Avenue, San Diego, California92123, USA(e:mail: [email protected]) (Accepted 18 February 2007)

SUMMARYGrowth, yield, and leaf nutrient concentrations were measured in ‘Hass’ avocado (Persea americana Mill.) trees grownon one of ten clonally-propagated rootstocks (‘Borchard’, ‘D9’, ‘Duke 7’, G1033, G755A, G755B, G755C, ‘Thomas’,‘Topa Topa’, or ‘Toro Canyon’) over a 10-year period in southern California. After 10 years, trees on ‘Borchard’ werelarger than trees on all other rootstocks. Trees on all rootstocks displayed an alternate-bearing pattern, typical ofavocado. Alternate-bearing was most pronounced in trees grafted onto ‘Topa Topa’ and ‘Toro Canyon’. Rootstocks inthe G755 series had the lowest alternate-bearing index, but also had the lowest yields.Trees on ‘Duke 7’ and ‘Borchard’had the highest cumulative yields, and trees on G755A, G755B, and G755C had the lowest yields. Differences in yieldwere due to differences in the number of fruit per tree, not individual fruit weight. When yield was evaluated in termsof canopy efficiency (kg fruit m–3), no rootstock outperformed ‘Duke 7’, the industry standard rootstock. Leafconcentrations of all nutrients examined (N, P, K, Ca, Mg, S, Zn, Cl, Mn, B, Fe, and Cu) were within, or close to therecommended ranges. P, Ca, and S were higher, and Fe was lower in high-yielding years in all rootstocks.

Avocado (Persea americana Mill.) production inCalifornia tends to be low compared to other avocado-

producing regions worldwide (www.avocadosource.com).Furthermore, the costs of production are increasing inCalifornia (Takele et al., 2002). Therefore, any factor thatcan increase yield is of interest to California growers.

Until the mid-1970’s, avocado was propagated onseedling rootstocks. It was not until the mid-1970’s thatclonally produced rootstocks for avocado were madeavailable for commercial use (Ben Ya’acov andMichelson, 1995). Clonal avocado rootstocks have beenselected primarily on the basis of their resistance toavocado root rot (Phytophthora cinnamomi Rands.;Menge et al., 1992). Increasingly, avocado rootstocks arealso being selected on the basis of their salt tolerance(Mickelbart and Arpaia, 2002), especially in regions suchas Israel, Australia, and California. Ultimately, theserootstocks must also allow the full yield potential of thescion to be realised, although this is usually a secondaryscreen after material has been selected based on itsrelative tolerance to stress. There has been littleevaluation of avocado rootstocks in terms of their effectson yield and yield components.

Apart from yield per se, consistent annual yield is animportant consideration in avocado production. Annualproduction is subject to fluctuations caused by alternate-bearing patterns. Seasons in which high yields occur areusually followed by a yield decline of approx. 50%(Anon., 2005). Differences in crop volumes from year-to-year may result in the loss of revenue during low-yieldyears, and in oversupply during high-yield years.Therefore, it is important to screen avocado rootstocks,not simply for their effect on average annual yield, butalso for their effect on alternate-bearing. The goal of thislong-term study was to evaluate ten clonal avocadorootstocks for horticultural factors of interest to growers.

MATERIALS AND METHODSPlant material and field environment

‘Hass’ avocado was clonally propagated on one of tenrootstocks (G755A, G755B, G755C, G1033, ‘Duke 7’,‘Borchard’, ‘D9’, ‘Thomas’, ‘Toro Canyon’, or ‘TopaTopa’). Most trees were planted in April 1986 at theUniversity of California South Coast Research andExtension Center (SCREC) in Irvine, California (33°44’ N;117°49’ W). Trees on G1033 and ‘Thomas’ rootstockswere planted in April 1987, in pre-selected sites that wereincluded in the original experimental design.Twenty treesper rootstock were used for all measurements. The treeswere planted at a spacing of 6.1 m ! 6.1 m on slightlyraised, 1.5 m-wide by 0.5 m-high berms to facilitate waterdrainage. The soil type was a Hanford sandy loam(average depth 18 m), and the site was determined to befree of avocado root rot (P. cinnamomi Rands.). At the

*Author for correspondence.3Current Address: Department of Horticulture and

Landscape Architecture, Purdue University, 625 AgriculturalMall Drive, West Lafayette, IN 47907-2010, USA.

4Current address: California Avocado Commission, 1251 E.Dyer Rd. Suite 200, Santa Ana, CA, 92705-5631, USA.

5Biostatistician (deceased), Department of Statistics,University of California, Riverside, CA, 92521-0124, USA.

6Current address: Kearney Agricultural Center, 9240Riverbend Ave., Parlier, CA, 93648, USA.

Journal of Horticultural Science & Biotechnology (2007) 82 (3) 460–466

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330CHILEAN JOURNAL OF AGRICULTURAL RESEARCH 79(2) APRIL-JUNE 2019

Rootstock affects the blend of biogenic volatile organic compounds emitted by ‘Hass’ avocadoRicardo Ceballos1, and Tommy Rioja2, 3*

1Instituto de Investigaciones Agropecuarias, INIA Quilamapu, Av. Vicente Méndez 515, Chillán, Chile.2Universidad Arturo Prat, Facultad de Recursos Naturales Renovables, Campus Huayquique Av. Arturo Prat s/n, Iquique, Chile. *Corresponding author ([email protected]).3Universidad de Tarapacá, Facultad de Ciencias Agronómicas, Campus Azapa km 12, Arica, Chile.

Received: 5 November 2018; Accepted: 12 February 2019; doi:10.4067/S0718-58392019000200330

ABSTRACT

Grafting, using tolerant rootstocks, has been necessary to increase avocado (Persea americana Mill.) production in drought, salinity, pest, and soil disease conditions. The avocado rootstock has shown an influence on scion vigor, nutrient absorption, fruit quality, and disease tolerance. Nevertheless, the avocado rootstock influence on the biogenic volatile organic compounds (BVOCs) emitted from ‘Hass’ shoots has not been reported. Our objective was to study the effect of two avocado rootstocks of the Mexican race on BVOC emitted by avocado ‘Hass’ shoots. We collected BVOCs emitted by ‘Hass’ avocado shoots grafted on ‘Mexicola’ and ‘Zutano’ rootstocks. All volatile collections were made from living plants for 24 h through a dynamic headspace technique. The chemical profiles were analyzed by gas chromatography coupled to a mass spectrometry (GC-MS). BVOC emission rates were highly variable in amount and composition. The monoterpene α-pinene was emitted at 5.06 ± 0.74, 0.73 ± 0.14, and 1.43 ± 0.61 μg mL-1 by graft ‘Hass’/‘Mexicola’, ‘Hass’/‘Zutano’ and ungrafted ‘Mexicola’, respectively. Grafted ‘Hass’ on ‘Mexicola’ emitted a wide variety of monoterpenes as β-pinene, cumene, 3-carene, R-limonene and (Z)-β-ocimene, whereas grafted plants on ‘Zutano’ only released α-pinene and cumene. Estragole was only detected on ungrafted ‘Mexicola’. We found that the chemical profile of volatile compounds released by ‘Hass’ grafted avocado plants was qualitatively and quantitatively influenced by rootstocks.

Key words: Avocado, headspace collection, Persea americana, plant volatiles, rootstock.

INTRODUCTION

Modern agricultural practice of grafting vegetal material and rootstock use has allowed cultivating in unfavorable conditions such as extreme temperatures, drought, salinity and flooding (Colla et al., 2010; Schwarz et al., 2010; Reeksting et al., 2014). Resistant and/or tolerant rootstocks to insect pests and pathogens increase the production, scion vigor, and organoleptic fruit quality (Warschefsky et al., 2016). Structural, biochemical and genetic factors influence the grafting process (Martínez-Ballesta et al., 2010). The scion-rootstock union and callus development produce molecular changes that affect scions’ defense mechanisms (Cookson et al., 2013; Trinchera et al., 2013; Lordan et al., 2017). On the other hand, the transport of RNA, DNA, phyto-hormones and proteins between scion and rootstock elicit phenotypic changes on grafted plants (Wang et al., 2016). Secondary metabolites such as alkaloids, non-protein amino acids, amines, cyanogenic glycosides, glucosinolates, terpenoids, and phenolics are constitutively produced by plants (Jamwal et al., 2018; Moreno-Medina et al., 2018). Biogenic volatile organic compounds (BVOC) are emitted through intercellular spaces, whereas stomas release them into the environment (Kegge and Pierik, 2010). As a result, terpenoids, aldehydes, green leaf volatiles (GLV), indole, and aromatic compounds are released (Loreto et al., 2014). These compounds have important physiological functions,

SCIENTIFIC NOTE

Grafting: Rootstock – Scion Interaction R O O T S T O C K E F F E C T S I N A V O C A D O

Effects of avocado (Persea americana Mill.) scion on arbuscularmycorrhizal and root hair development in rootstockBo Shu, Liqin Liu, Dengwei Jue, Yicheng Wang, Yongzan Wei and Shengyou Shi

South Subtropical Crops Research Institute, Chinese Academy of Tropical Agricultural Science, Key Laboratory ofTropical Fruit Biology, Ministry of Agriculture, Zhanjiang, P. R. China

ABSTRACTGrafting is an important process to propagate horticulture plants; how-ever, the mechanism through which the scion affects the absorption ofrootstock remains poorly understood. The effects of the scion on AMfungi types in the rhizosphere soil of rootstock and the absorption ofmycorrhizal root were determined in this study. Composition of arbus-cular mycorrhizal (AM) fungi, soil assessment, spore density, hyphallength density, glomalin-related soil protein (GRSP) content in rhizo-sphere soil, root hair morphology and AM colonisation rate were mea-sured among ‘Kampong’ avocado rootstocks grafted with five scions and‘Kampong’ seedling trees. Results showed the main types of AM fungi inavocado seedling trees and trees grafted with five scions were nearlyidentical. However, the proportion of main genera exhibited differences.In addition, alkali-hydrolysable N, alkali-hydrolysable P and available K inrhizosphere soil, root hair density, AM colonization, spore density, hyphallength and GRSP content suggested the absorption of ‘Kampong’ root-stocks grafted with ‘Monroe’, ‘Wilson seedless’, ‘Hass’ and ‘Tonnage’possessed stronger absorption than ‘Kampong’ seedling trees becauseof high AM colonisation and root hair density. This study suggestedscions regulated both the AM and root hair development systematicallyand laid the foundation for future research of AM-enhancing avocadoproduction.

ARTICLE HISTORYReceived 3 December 2016Accepted 6 April 2017

KEYWORDSAvocado; arbuscularmycorrhizal fungicomposition; graft;rhizosphere soil; absorption

Introduction

Avocado (Persea americana Mill.) is a tropical mycorrhizal tree cultivated for its fruits (González-Cortés et al. 2012; Carreón-Abud et al. 2015). The hypha of arbuscular mycorrhizal (AM) and roothairs are the main absorption structures of mycorrhizal trees (Wu et al. 2015) and avocados.Previous research showed that avocado relies heavily on AM fungi to increase water or mineralnutrient absorption and enhance resistance to Phytophthora root rot (Mataré & Hattingh 1978).Avocado also possesses root hairs to supplement the AM absorption pathway. Thus, both AM androot hair developments of avocado are important to enhance its yield and quality formation.

Grafting is a well-implemented technology in avocado tree cultivation. The yield and quality ofscion varieties has proven of more interest to cultivation than the absorption of rootstock.Absorption, including AM and plant direct pathways, is the foundation of fruit yield and quality(Behn 2008). Previous research showed that the genotype of citrus scion exerts a greater impact onthe AM fungi community structure than that of rootstock in different soil types (Song et al. 2015).

CONTACT Shengyou Shi [email protected] South Subtropical Crops Research Institute, Chinese Academy of TropicalAgricultural Science, Key Laboratory of Tropical Fruit Biology, Ministry of Agriculture, Zhanjiang, P. R. China

Supplemental data for this article can be accessed here.

ARCHIVES OF AGRONOMY AND SOIL SCIENCE, 2017VOL. 63, NO. 14, 1951–1962https://doi.org/10.1080/03650340.2017.1317921

© 2017 Informa UK Limited, trading as Taylor & Francis Group

Grafting: Rootstock – Scion Interaction S C I O N E F F E C T S I N A V O C A D O

Quantify inheritance of rootstock effects on ‘Hass’ avocado

North – West Andes S A M P L I N G : 8 P L A N T A T I O N S , 2 4 0 T R E E S

North – West Andes S A M P L I N G : 8 P L A N T A T I O N S , 2 4 0 T R E E S

Quantify inheritance of rootstock effects on ‘Hass’ avocado

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3.5

h2 Thousands of Fallen fruits

Den

sity

h2 = 0.45

(c)

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0 10 20 30 40 50

0

20

40

60

80

100

Thousands of Fallen fruits^

Thou

sand

s of

Fal

len

fruits

R2 = 0.73

(d)

0.0 0.2 0.4 0.6 0.8

0

1

2

3

h2 Low weight (number of fruits)

Den

sity

h2 = 0.41

(e)

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0 50 100

0

50

100

150

200

250

300

Low weight (number of fruits)^

Low

wei

ght (

num

ber o

f fru

its)

R2 = 0.69

(f)

0.0 0.2 0.4 0.6 0.8

0

1

2

3

h2 Exportation (number of fruits)

Den

sity

h2 = 0.37

(g)

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0

500

1000

1500

2000

Exportation (number of fruits)^

Expo

rtatio

n (n

umbe

r of f

ruits

)

R2 = 0.65

(h)

0.0 0.2 0.4 0.6 0.8

0

1

2

3

4

h2 Number of fruits presenting Thrips

Den

sity

h2 = 0.33

(i)

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0 50 100 150 200 250

0

200

400

600

800

1000

Number of fruits presenting Thrips^

Num

ber o

f fru

its p

rese

ntin

g Th

rips

R2 = 0.61

(j)


0.0 0.2 0.4 0.6 0.8

0

1

2

3

4

h2 Trunk eight (cm)

Den

sity

h2 = 0.37

(a)

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20 30 40 50 600

20

40

60

80

100

120

Trunk eight (cm)^

Trun

k ei

ght (

cm)

R2 = NA

(b)

0.0 0.2 0.4 0.6 0.8

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

h2 Thousands of Fallen fruits

Den

sity

h2 = 0.45

(c)

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0 10 20 30 40 50

0

20

40

60

80

100

Thousands of Fallen fruits^

Thou

sand

s of

Fal

len

fruits

R2 = 0.73

(d)

0.0 0.2 0.4 0.6 0.8

0

1

2

3

h2 Low weight (number of fruits)

Den

sity

h2 = 0.41

(e)

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0 50 100

0

50

100

150

200

250

300

Low weight (number of fruits)^

Low

wei

ght (

num

ber o

f fru

its)

R2 = 0.69

(f)

0.0 0.2 0.4 0.6 0.8

0

1

2

3

h2 Exportation (number of fruits)

Den

sity

h2 = 0.37

(g)

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0 200 400 600 800

0

500

1000

1500

2000

Exportation (number of fruits)^

Expo

rtatio

n (n

umbe

r of f

ruits

)

R2 = 0.65

(h)

0.0 0.2 0.4 0.6 0.8

0

1

2

3

4

h2 Number of fruits presenting Thrips

Den

sity

h2 = 0.33

(i)

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0 50 100 150 200 250

0

200

400

600

800

1000

Number of fruits presenting Thrips^

Num

ber o

f fru

its p

rese

ntin

g Th

rips

R2 = 0.61

(j)

Frec

uenc

y ( T

runk

eig

ht ) (a)

0

2

4

6

8

10

12

14

16

0.38

(b)

0.36

(c)

0.64

(d)

0.64

Frec

uenc

y ( F

alle

n fru

its ) (e)

0

2

4

6

8

10

12

14

16

0.46

(f)

0.44

(g)

0.74

(h)

0.73

Frec

uenc

y ( L

ow w

eigh

t ) (i)

0

2

4

6

8

10

12

14

16

0.36

(j)

0.33

(k)

0.64

(l)

0.62

Frec

uenc

y ( E

xpor

tatio

n ) (m)

0

2

4

6

8

10

12

14

16

0.33

(n)

0.37

(o)

0.58

(p)

0.65

h2 (Phenotype)

Frec

uenc

y ( T

hrip

s )

(q)

0

2

4

6

8

10

12

14

16

0.16 0.21 0.26 0.31 0.36 0.41 0.46

0.35

h2 (Marker)

(r)

0.16 0.21 0.26 0.31 0.36 0.41 0.46

0.34

R2 (Phenotype)

(s)

0.34 0.44 0.54 0.64 0.74

0.6

R2 (Marker)

(t)

0.34 0.44 0.54 0.64 0.74

0.62

Frec

uenc

y ( T

runk

eig

ht ) (a)

0

2

4

6

8

10

12

14

16

0.38

(b)

0.36

(c)

0.64

(d)

0.64

Frec

uenc

y ( F

alle

n fru

its ) (e)

0

2

4

6

8

10

12

14

16

0.46

(f)

0.44

(g)

0.74

(h)

0.73

Frec

uenc

y ( L

ow w

eigh

t ) (i)

0

2

4

6

8

10

12

14

16

0.36

(j)

0.33

(k)

0.64

(l)

0.62

Frec

uenc

y ( E

xpor

tatio

n ) (m)

0

2

4

6

8

10

12

14

16

0.33

(n)

0.37

(o)

0.58

(p)

0.65

h2 (Phenotype)

Frec

uenc

y ( T

hrip

s )

(q)

0

2

4

6

8

10

12

14

16

0.16 0.21 0.26 0.31 0.36 0.41 0.46

0.35

h2 (Marker)

(r)

0.16 0.21 0.26 0.31 0.36 0.41 0.46

0.34

R2 (Phenotype)

(s)

0.34 0.44 0.54 0.64 0.74

0.6

R2 (Marker)

(t)

0.34 0.44 0.54 0.64 0.74

0.62

Frec

uenc

y ( T

runk

eig

ht ) (a)

0

2

4

6

8

10

12

14

16

0.38

(b)

0.36

(c)

0.64

(d)

0.64

Frec

uenc

y ( F

alle

n fru

its ) (e)

0

2

4

6

8

10

12

14

16

0.46

(f)

0.44

(g)

0.74

(h)

0.73

Frec

uenc

y ( L

ow w

eigh

t ) (i)

0

2

4

6

8

10

12

14

16

0.36

(j)

0.33

(k)

0.64

(l)

0.62

Frec

uenc

y ( E

xpor

tatio

n ) (m)

0

2

4

6

8

10

12

14

16

0.33

(n)

0.37

(o)

0.58

(p)

0.65

h2 (Phenotype)

Frec

uenc

y ( T

hrip

s )

(q)

0

2

4

6

8

10

12

14

16

0.16 0.21 0.26 0.31 0.36 0.41 0.46

0.35

h2 (Marker)

(r)

0.16 0.21 0.26 0.31 0.36 0.41 0.46

0.34

R2 (Phenotype)

(s)

0.34 0.44 0.54 0.64 0.74

0.6

R2 (Marker)

(t)

0.34 0.44 0.54 0.64 0.74

0.62

Frec

uenc

y ( T

runk

eig

ht ) (a)

0

2

4

6

8

10

12

14

16

0.38

(b)

0.36

(c)

0.64

(d)

0.64

Frec

uenc

y ( F

alle

n fru

its ) (e)

0

2

4

6

8

10

12

14

16

0.46

(f)

0.44

(g)

0.74

(h)

0.73

Frec

uenc

y ( L

ow w

eigh

t ) (i)

0

2

4

6

8

10

12

14

16

0.36

(j)

0.33

(k)

0.64

(l)

0.62

Frec

uenc

y ( E

xpor

tatio

n ) (m)

0

2

4

6

8

10

12

14

16

0.33

(n)

0.37

(o)

0.58

(p)

0.65

h2 (Phenotype)

Frec

uenc

y ( T

hrip

s )

(q)

0

2

4

6

8

10

12

14

16

0.16 0.21 0.26 0.31 0.36 0.41 0.46

0.35

h2 (Marker)

(r)

0.16 0.21 0.26 0.31 0.36 0.41 0.46

0.34

R2 (Phenotype)

(s)

0.34 0.44 0.54 0.64 0.74

0.6

R2 (Marker)

(t)

0.34 0.44 0.54 0.64 0.74

0.62

100 randomizations


Estimates of rootstock–mediated heritabilities (h2) were significant for 5 of the 20 measured traits and ranged from 0.32 to 0.46 h2 with model fits (R2) ranging from 0.58 to 0.74 across plantations.


Estimates of rootstock–mediated heritabilities (h2) were significant for 5 of the 20 measured traits and ranged from 0.32 to 0.46 h2 with model fits (R2) ranging from 0.58 to 0.74 across plantations.

h2 r2 h2 r2 h2 r2

Morphological Trunkheight 0.38 0.64 0.36 0.64 0.37 0.64

Eco-physiological Totalnumberoffruits 0.46 0.74 0.44 0.73 0.45 0.73

Damagebylowweight 0.36 0.64 0.33 0.62 0.35 0.64

Damagebythrips 0.35 0.60 0.34 0.62 0.34 0.60

Exportationquality 0.33 0.58 0.37 0.65 0.32 0.58

SSRs Phenotype Genetic

Harvest(numberoffruits)

TraitTraittype


Inheritance of Rootstock Effects in Avocado C O N C L U S I O N S

•  We identified significant rootstock effects for various harvest and quality traits (i.e. total number of fruits, number of fruits with low weight, number of fruits damaged by thrips, and number of fruits with exportation quality).



•  The only morphological trait that we found having a significant heritability value mediated by the rootstock was trunk height.



•  The only morphological trait that we found having a significant heritability value mediated by the rootstock was trunk height.

•  These findings suggest the inheritance of rootstock effects on a surprisingly wide spectrum of ‘Hass’ avocado traits.

Inheritance of Rootstock Effects in Avocado P E R S P E C T I V E S

•  This research is, up to date, the most cohesive evidence of inheritance of rootstock effects in any fruit tree.



•  Further heritability estimates should be gathered using a diverse panel of clonal rootstocks and new traits.




•  Genotyping-by-sequencing will enable us understanding the genetic architecture of rootstock-mediated traits.




•  Genotyping-by-sequencing will enable us understanding the genetic architecture of rootstock-mediated traits.

•  This work reinforces the importance of considering the rootstock-

scion interaction to enhance our understanding of the consequences of grafting and speed up fruit tree breeding programs.

¡Gracias!

PRESENTATION: Inheritance of rootstock effects in avocado ... · Inheritance of rootstock effects...

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