Symbioses: Plant, Animal, and Microbe Interactions
Ortiz , Irma , Schwartz, Allison , Sanders, Erin R. , Diener, Andrew C. , Hirsch, Ann M. .
A Bacillus strain isolated by undergraduate students at UCLA promotes plant growth by procuring soil nutrients and may also serve as a biological control agent.
The plant microbiome in the rhizosphere consists of both bacteria and fungi that exhibit many beneficial effects on plant growth. The Plant-Growth Promoting Bacteria (PGPB) offer an important solution to the negative consequences of adding chemical fertilizers and pesticides by enhancing plant yield, producing phytohormones such as auxin or interfering with ethylene synthesis, controlling plant pathogens, and obtaining critical nutrients including iron, nitrogen, and phosphorous. In this study, we analyzed the mechanisms whereby a Bacillus strain, isolated from the Mildred E. Mathias Botanical Garden and investigated by two UCLA undergraduate courses, could mediate a positive growth response on legumes such as Medicago truncatula, Lotus japonicus, and Pisum sativum. From various assays, we determined that the improvements in plant growth are likely to be the result of a combination of bacterial factors including IAA synthesis, siderophore production, and phosphate solubilization. Because PGPB are also known to protect plants from pathogenic fungi and bacteria, a co-culture assay was established on potato dextrose agar (PDA) plates. The plates were either left uninoculated or spotted with a number of different fungal pathogens, and then co-inoculated with the new Bacillus strain or B.subtilis, a well-known biocontrol agent. Our results so far suggest that the newly isolated Bacillus strain is a weaker biological control agent than B. subtilis.
We acknowledge the financial support of the Shanbrom Family Foundation and the UCLA Office of Instructional Development for courses MIMG 121A and MCDB150L. Irma Ortiz was supported by NIH grant GM55052 to Dr. Richard L. Weiss (UCLA). Other undergraduates who participated in this research are Rudy Benitez, Nigar Yusifova, Christine Kim, Ethan Mathews, Mary Motamedinia, Archie McCoy, Han Soul Kim, Kayoko Hanamoto, Walter Kim, Judy Wong, Brittany Yee, and Faith Oh.
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1 - University of California-Los Angeles, Molecular, Cell & Developmental Biology, 621 Charles Young Dr., South, Los Angeles, CA, 90095-1606, USA
2 - University of California-Los Angeles, Microbiol, Immunol, and Mol Genetics, Los Angeles, CA, 90095, USA
3 - University of California-Los Angeles, MCD Biol and Mol Biol Inst, 621 Charles Young Dr., South, Los Angeles, CA, 90095-1606, USA
plant growth promoting bacteria.
Presentation Type: Oral Paper:Papers for Topics
Location: Portland Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 3:45 PM