Plants have the remarkable ability to shed organs-such as leaves, flowers, and fruit-as a normal stage of their life cycle. Abscission (cell separation) occurs in specialized cell types and requires the secretion of enzymes that dissolve the glue-like substance holding neighboring cells together. The focus of the proposed research is to investigate the link between cell separation and the secretory pathway revealed by studies of the NEVERSHED (NEV) gene. Mutations in NEV, a predicted G-protein regulator, prevent floral organ shedding in Arabidopsis and cause cellular defects in vesicle trafficking. These data suggest that NEV may regulate the movement of specific proteins required for cell separation.
Using genetic, molecular, cell biological and biochemical approaches, the following questions will be addressed. (1) What pathway does NEV act in to control abscission? A set of mutants that restore floral organ shedding in the nev mutant will be characterized. Analysis of these mutants should identify other proteins that interact with or act downstream of NEV during the cell separation process. (2) How does NEV function and what stage of vesicle trafficking does it regulate? Assays will test NEV enzymatic activity using representative G-proteins. To determine the site of NEV activity within the cell, the location of known markers of plant subcellular compartments will be compared with that of the NEV protein. (3) What other roles does NEV play during development? To fully define NEV function, mutations in three other closely-related genes will be identified. By characterizing plants with mutations in NEV and each related gene, additional roles likely masked by genetic redundancy will be uncovered.
The broader impacts of this research include training opportunities for young scientists and the potential to improve crop yields and simplify harvesting that would result from a clearer understanding of the molecular mechanisms that control abscission.
