Symposium I: New Advances & Insights in Plant Biology

Abs # 10001: Recognition and Rejection of Self Pollen in Crucifers

Presenter:	Nasrallah, June B, jbn2@cornell.edu
Authors	Nasrallah, June B (A)
Affiliations:	(A): Cornell University

In self-incompatible members of the crucifer family, the arrest of self pollen occurs at the surface of the epidermal cells of the stigma and is manifested by inhibition of pollen hydration, germination, or pollen tube invasion of the stigma epidermis. The genetic determinant of SI specificity in this family is the S locus, a complex locus that contains two highly polymorphic and co-evolving genes. One gene encodes a receptor serine-threonine kinase that spans the plasma membrane of the stigma epidermis, and a second gene encodes a small cysteine rich peptide that is localized in the pollen coat and is the ligand for the stigma receptor. Recognition of self pollen is based on allele-specific interactions between the stigma receptor and its pollen ligand. These interactions result in activation of the receptor and presumably trigger a poorly understood signaling cascade within the stigma epidermal cell that leads ultimately to the inhibition of pollen tube emergence or growth. Progress in our analysis of receptor-ligand interactions and the development of novel approaches for elucidating the SI signal transduction pathway and for determining the biochemical cause for inhibition of self pollen will be discussed.