Developmental and Structural Section
Schwartz, Allison , Ortiz , Irma , Sanders, Erin R. , Demason, Darleen , Hirsch, Ann M. .
A newly isolated Bacillus strain affects legume plant architecture and pea nodule morphology by secreting auxin.
A Gram-positive, elongated bacterium, designated 30N-5, was isolated from the Mildred E. Mathias Botanical Garden by UCLA undergraduate students after plating the soil suspension on a nitrogen-free medium. A phylogenetic analysis of a partial 16S rDNA sequence of strain 30N-5 revealed it to be 100% similar to Bacillus simplex strain NH259. Even though the initial isolation was made on a nitrogen-free medium, no evidence for nifH, one of three structural genes encoding the enzyme nitrogenase, was observed. Nevertheless, a profoundly positive effect on plant growth was observed. Upon inoculation onto the roots of both wild-type and the cytokinin-receptor mutant hit1-1 of Lotus japonicus, a model legume, B. simplex 30N-5 was found to alter the architecture of the inoculated plant by increasing root and shoot length as well as lateral root number and plant biomass. The auxin responses of the plants were visualized using a DR5::GUS reporter construct in pea (1). The DR5-auxin responsive element drives the beta-glucuronidase (GUS) reporter gene. Differences in nodule morphology were observed through a comparison of pea roots from uninoculated, Bacillus- and Rhizobium-inoculated roots, as well as from roots co-inoculated with both bacteria. The data strongly suggest that this new Bacillus strain influences nodule morphology in an auxin-dependent manner.
(1) DeMason DA, Polowick PL (2009) Patterns of DR5::GUS expression in organs of pea (Pisum sativum). Inter J Plant Sci 170: 1-11.
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, Dept. of Microbiol, Immunol, and Mol Genetics, Los Angeles, CA, 90095, USA
3 - University Of California, Botany And Plant Sciences, 900 University Ave., Riverside, CA, 92521, USA
4 - 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 Sections
Location: Lindell A/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 4:15 PM