“Elucidating the function of OsSULTR3;6 through seed physiology and mineral nutrition”
Rice (Oryza sativa) is one of the most important agricultural crops in the world, but diseases such as bacterial leaf streak (BLS), caused by Xanthomonas oryza pv. oryzicola (Xoc), lead to significant constraints on the production of rice. Xoc uses Transcriptional activator-like (Tal) effectors to enhance rice susceptibility through the upregulation of the Oryza sativa Sulfate Transporter 3;6 (OsSULTR3;6). OsSULTR3;6 belongs to a gene family of membrane transporters characterized for their role in sulfate and phosphate transport. However, there is no published data on the function of OsSULTR3;6. Prior observations using seeds from
CRISPR-edited plants lacking OsSULTR3;6 (Δsultr3;6, courtesy of Dr. Adam Bogndanove) in the Piñeros Lab indicate Δsultr3;6 seeds have a germination defect of 30%. This phenotype drove my summer research to functionally characterize the role of OsSULTR3;6 from the perspective of seed physiology and nutrition.
We hypothesized that either enhanced sulfate or phosphate ion nutrition were causing the germination defect in Δsultr3;6. Germination assays found that the germination defect was unable to be rescued, indicating that the mutant seeds were nonviable. Ionomic analyses performed using inductively-coupled plasma optical emission spectroscopy (ICP-OES), ion chromatography (IC), and phytate assays showed higher phosphorus, phosphate, and phytate content in the mutant seeds, but no differences in sulfur or sulfate content were found.
Increased phosphate levels have been linked to lower starch content and seed nonviability, but seed weight and starch assays showed no differences in seed morphology or starch content between the wildtype and mutant seeds. Current data supports OsSULTR3;6 likely encodes for a phosphate transporter, and additional work will be done to elucidate the connection between enhanced phosphate nutrition and seed nonviability.
While the REU program was only ten weeks, I’ve learned a lot in my short time here. My project exposed me to many additional methods for characterizing protein functions, and gave me a much greater appreciation for plant science research. The experience I gained this summer has been very different from work I’ve done in the past, and I’m excited to further explore this area of study in the future. While I had some ideas on my potential career path, my time here has granted me valuable insight on my next steps after college. The time I’ve spent this summer has gone beyond my expectations, and the connections I’ve made are invaluable.