Agricultural productivity is driven by photosynthetic activity, which occurs in tissues of plant shoot systems. A major limitation to shoot size (and productivity) arises from adverse soil conditions, such as drought, compaction, and saline conditions. Plant roots are biological sensors that detect these adverse conditions, and by an unknown mechanism, cause the shoot system to slow or arrest growth. This project will test whether the root-to-shoot stress signal is the same mobile signaling molecule that is produced in Arabidopsis bps1 mutants. BYPASS (BPS) proteins function to prevent synthesis of a small metabolite, the bps signal, which moves from the root and arrests shoot growth. The principle investigator hypothesizes that the bps signal is a previously undescribed plant hormone, and preliminary data indicate that it stops growth by interfering with stem cell identity. Approaches include a full analysis of gene expression changes in shoots treated with the bps signal, and molecular and genetic experiments to uncover the mechanism of bps signal gene regulation. Experiments will also investigate whether, in normal plants, the bps signal is produced in response to stress. These experiments will use transgenic Arabidopsis plants that carry markers that respond to the bps signal and will use metabolomic approaches to measure bps signal levels. These investigations are critical for developing strategies to reducing agricultural crop losses due to soil-related stresses. Investigators involved in this research also provide educational opportunities to the community including girl scouts, K-12 schools, prisoners, and local garden clubs, and develop laboratory teaching materials for college and high school students.
