In multicellular organisms, some cells specialize in secretory functions. Examples of secretory cells include certain vascular cells that secrete nutrients for distribution, epidermal cells that export protective compounds, nectaries that secrete solutes to reward pollinators, tapetal cells that nourish reproductive cells, and seed coat cells that secrete nutrients to fill seeds. Pathogens apparently tap into nutrient resources by manipulating nutrient secretion systems. Despite the importance of secretory cells, the understanding of these cells and biological processes is limited. This project seeks to identify the fundamental mechanisms of secretory cells, to permit the enhancement of crop quality and yield, of the interaction of plants with other organisms, and of stress tolerance. The project team combines expertise in the genome-wide analysis of individual cell types (Bailey-Serres, & Girke, UC Riverside), membrane transport processes (Frommer, Carnegie, Stanford) and genome editing (Yang, Iowa State U). The project is expected to provide new tools and information of value for agriculture. Concepts and resources developed by the project will be integrated into classes at 2-year institutions with substantial enrollments of underserved students. A public website, blog and forum will provide discussion of genome editing technologies, with the participation of experts and local community colleges.
The SECRETome project seeks to identify specific components and regulatory mechanisms of the varied functions of plant secretory cells. To enable an evaluation of gene function within individual cells and tissues, imaging, ribosome-mRNA complex capture, gene editing and informatics will be employed in an integrated fashion. A comparative approach will be enabled through the analysis of both the crop rice and the reference plant Arabidopsis. Specific aims include (1) the profiling of ribosome-associated transcripts (translatomes) of key secretory cell types with prominent roles in secretion or nursing of neighboring cells in the two species, in the context of two developmental processes and two biotic interactions, (2) the identification of characteristic gene expression patterns and networks for specific secretory cell-types to facilitate selection of candidate genes for functional studies, and (3) the validation and characterization of secretory cell-specific promoters and candidate gene functions, including subcellular location, biochemistry, and reverse-genetic phenotype. The secretory cell-specific promoters will be valuable for other studies (e.g., to control genes for cell-specific processes that enhance pathogen defense, beneficial microbial interactions, fertility or seed quality). The results will provide broad new insights into the intersection between cell function, development and biotic interactions. The project will produce public resources and discourse forums regarding genomic editing with the engagement of undergraduate students.
