Plant development involves coordination between roots, which detect water and nutrient levels and shoots, the above-ground portion of the plant. However, the nature of root-derived signals and how they work to control shoot growth is largely unknown. Recent analysis of an Arabidopsis mutant called bypass1 (bps1) showed that, in this mutant, the roots continually produced a signal that moved through the plant and was able to stop shoot growth. This result suggests that BYPASS1 (BPS1) functions to stop production of a long-distance signal that might normally be used to control plant growth. The Sieburth lab will carry out experiments directed toward understanding the root-to-shoot signaling controlled by BPS1. Research will use genetic, biochemical and cell biological approaches to address the following three questions: (1) what is the mobile signal; (2) what does BPS1 interact with normally that suppresses signal production; and (3) how does the signal inhibit shoot growth? The experiments are expected to identify a branch of the carotenoids that are required for signal production. The work is also expected to identify cellular proteins that interact with BPS1: proteins which might assist in directing the plant to generate the signal or function to transmit environmental signals to BPS1. Finally, the work is also expected to identify how shoot growth is controlled (e.g. by preventing cell cycle progression or by inhibiting cell expansion). This work will provide insight into root-to-shoot signaling while training undergraduate, graduate, and post-doctoral students. Moreover, root-to-shoot signals are believed to profoundly reduce agricultural productivity, especially in response to drought. Insight into the BPS1 pathway may provide a rational basis for engineering plants with altered responses to the root-derived signal, thus leading to boosts in agricultural productivity.
