Proceedings of the National Academy of Sciences of the United States of America

About the PNAS Member Editor
Name Nasrallah, June B.
Location Cornell University
Primary Field Plant Biology
 Election Citation
Nasrallah has been a leader in elucidating the molecular mechanisms responsible for the self-incompatibility that prevents self-fertilization in plants. She has identified the genes that are expressed by the female and male parts of the flower that interact to cause rejection of self-pollen. Her recent research explores the genetic basis for the evolutionary switches from outcrossing to self fertility.
 Research Interests
My research focuses on the study of the cell-cell interactions required for plant reproduction. By studying the highly specific interactions between the pollen or pollen tube and the female pistil, we expect to understand the mechanisms underlying reproductive success and mating specificity within and between species, and to shed light on the more general problem of cell-cell communication in plants. A long-standing interest has been to investigate the mechanism of self-incompatibility in crucifers, a major barrier to self-fertilization that leads to the arrest of self-related pollen grains at the surface of the pistil. We showed that recognition of self-pollen results from allele-specific interactions between a receptor kinase expressed on the epidermal cells of the pistil and its ligand, a small peptide expressed on the surface of pollen grains. By transformation with a pair of receptor and ligand genes, we rendered the self-fertile species A. thaliana self-incompatible, thus demonstrating that these two proteins are the major determinants of the out-breeding mode of reproduction in crucifers. Our current work aims at understanding the basis of specificity in receptor-ligand interaction, how receptors and ligands co-evolve to generate new self-recognition specificities, and the signal transduction pathway that leads to pollen inhibition. We are also interested in characterizing the genetic basis of evolutionary switches from out-crossing to self-fertility, and thus understand a major process in the reproductive isolation of plant species.

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