Brassinosteroids (BR) have emerged as an important class of plant steroid hormones implicated in promoting cell division and elongation and improving plant responses to stress. Application of naturally occurring BR to plants has been shown to increase yield in many different species. In addition, several synthetic BR analogs have been generated, some of which appear to have biological activity similar to or greater than naturally occurring BR. These synthetic compounds may provide a means to increase crop yields by taking advantage of the ubiquitous plant response to this class of growth regulators. Agritope's Phase I research objective will be to characterize the biological activity of two novel synthetic BR analogs. For our initial tests in plants, we will evaluate the ability of both natural and synthetic compounds to rescue a BR biosynthetic mutant phenotype in Arabidopsis and induce expression of BR-regulated genes. During Phase I, we will also generate transgenic lines of Arabidopsis and tomato that overexpress genes involved in the biosynthesis and perception of BR. These transgenic lines will be used to compare the effects of exogenous application of synthetic BR analogues with the effects of manipulating the endogenous BR biosynthetic and recognition pathways.
Anticipated Results/Potential Commercial Applications of Research: By studying the effects of the synthetic BR analogues on biosynthetic mutants, we hope to demonstrate that the synthetic compounds function through the same recognition and signaling pathways as naturally occurring BR. The synthetic BR analogues can be evaluated for their ability to promote growth and improve field performance of a model crop species, i.e., tomato. The transgenic lines generated during Phase I research will also be used in laboratory and field tests to determine whether application of the synthetic BR analogues to plants overexpressing the putative hormone receptor will lead to further increases in biomass and/or yield.
