Watts, Austin; Crook, M. B. (Weber State University)
Faculty Advisor: Crook, Matthew (College of Science, Microbiology)
Auxin is a known growth hormone for plants and many plant-beneficial bacteria are known to produce it. It has previously been shown that Rhizobium sp. IRBG74 promotes growth of rice, but the mechanism is unknown. We hypothesized that Rhizobium sp. IRBG74 accomplishes this by production and secretion of auxin. To address this hypothesis, we first performed a bioinformatic analysis to identify putative auxin biosynthesis genes in the genome of IRBG74 using BLAST with known auxin biosynthesis genes as queries. To test whether the genes identified by BLAST play a role in promoting growth of rice, we are making in-frame deletions of each one. Briefly, we use overlap-extension PCR to create and stitch together deletion fragments and then we clone these fragments into the sacB deletion vector pJQ200SK. The target genes are then disrupted by homologous recombination and then deintegration is selected for with sucrose. After this is done we test the mutant to verify the deletion occurred by PCR. Once the deletion mutants are verified, each one is tested on rice seedlings and compared to wild-type IRBG74. Rice growth is quantified by shoot dry weight and by root branching, as measured using ImageJ.