Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native...
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![Page 1: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/1.jpg)
Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities
Rachel L. MelnickPh.D. CandidateDepartment of Plant PathologyThe Pennsylvania State University
Department of Plant Pathology
![Page 2: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/2.jpg)
Department of Plant Pathology
Theobroma cacao L.•Tropical understory
perennial
•Seeds processed into chocolate
•Home to wide range of fungal endophytes
![Page 3: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/3.jpg)
Department of Plant Pathology
Diseases of cacao•Main limiting factor
![Page 4: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/4.jpg)
Department of Plant Pathology
Biological Control: Pod Diseases•Cherelle wilt
▫Thought to be physiological thinning mechanism
▫Likely has biological component•Frosty Pod•Black Pod•Witches’ broom
•Focus on biocontrol for disease management
![Page 5: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/5.jpg)
Department of Plant Pathology
Hypothesis •Endophytic Bacillus spp. may provide
sustainable control of cacao diseases, through activation of plant defense mechanisms and alteration of the microbial ecology of tree
![Page 6: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/6.jpg)
Department of Plant Pathology
Bacterial endophytes
•Bacillus spp. isolated from pods, leaves, branches, floral cushions at the INIAP station in Pichilingue, Ecuador
•Screened for elite qualities for biocontrol agent
•Identified 4 potential biological control agents
![Page 7: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/7.jpg)
Department of Plant Pathology
Biological Control: Witches’ Broom•Bacillus pumilis ET reduced overall
disease severity through dry and rainy seasons
Days after bacterial application
0 20 40 60 80 100 120
Dis
ea
se
se
ve
rity
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
A20 CT Control CR ET
A
AB
BBB
![Page 8: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/8.jpg)
Department of Plant Pathology
Biological Control: Pod Diseases•B. pumilis ET reduced cherelle wilt in
genotype CCN-51, but not diseases
•See poster P-714 for more information…
![Page 9: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/9.jpg)
Department of Plant Pathology
What is known to date…•Bacillus pumilis ET works as a biological
control agent, but how?
•Antibiosis – Reduced growth of M. roreri, M. perniciosa, and P. capsici & chitinase producer
• Induced resistance – Activates expression of cacao defense genes
•Niche displacement?
![Page 10: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/10.jpg)
Department of Plant Pathology
Niche displacement•Thought that most endophytes are neutral
in terms of plant health
•Introducing beneficial endophytes likely displaces neutral microbes to increase benefits
•How to test?
![Page 11: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/11.jpg)
Department of Plant Pathology
The trees…•Sprayed branches of cacao trees in
cardinal directions with 1x108 CFU/ml at beginning of rainy season (Jan) & again in end of March▫Three replicate trees per treatment
•Collected leaves from branches in March and May
•Preserved and shipped in RNALater
![Page 12: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/12.jpg)
Department of Plant Pathology
ARISA
•Automated Ribosomal Intergenic Spacer Analysis
•Extracted genomic DNA•Nested PCR with bacilli specific primers
following Garbeva et al. 2003
16S 23StRNA
Microb Ecol. 2003. 45: 302-316
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Department of Plant Pathology
Abundance & Diversity in March
Applied species
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Department of Plant Pathology
Abundance in May
![Page 15: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/15.jpg)
Department of Plant Pathology
Witches’ Broom
Days after bacterial application
0 20 40 60 80 100 120
Dis
ea
se
se
ve
rity
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
A20 CT Control CR ET
A
AB
BBB
Reapplication
May Sampling
![Page 16: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/16.jpg)
Department of Plant Pathology
Conclusions•B. pumilis ET appears to decrease
diversity of native microbes
•Indications that application of B. pumilis ET may displace neutral endophytes
![Page 17: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/17.jpg)
Department of Plant Pathology
Future work…•Statistical analysis of the data presented
today to get more exact measures of diversity & abundance
•ARISA with universal bacterial primers▫As soon as I get home!
•ARISA with universal fungal primers
•ARISA of pods
![Page 18: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/18.jpg)
Department of Plant Pathology
Acknowledgements
• Penn State▫Paul Backman▫Scott Geib
• USDA-ARS SPCL▫Bryan Bailey
• INIAP-EET▫Carmen Suárez▫Karina Solis▫Danilo Vera
Research Support:• USAID IPM-CRSP• USDA-ARS SPCL• Penn State College
of Ag. Sci. Graduate Student Competitive Grant
Travel Support:• APS Potomac
Division Travel Award
• The Eddie Echandi & H. David Thurston Award APS Foundation Award
• Penn State College of Ag. Sci. Student Travel Award
![Page 19: Impact of application of endophytic Bacillus spp. for biocontrol of cacao diseases on native microbial communities Rachel L. Melnick Ph.D. Candidate Department.](https://reader035.fdocuments.us/reader035/viewer/2022062719/56649ed85503460f94be643f/html5/thumbnails/19.jpg)
Department of Plant Pathology
Questions????