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Self-incompatibility (SI) is a general name for several genetic mechanisms that prevent self-fertilization in sexually reproducing organisms, and thus encourage outcrossing and allogamy. It is contrasted with separation of sexes among individuals ( dioecy ), and their various modes of spatial ( herkogamy ) and temporal ( dichogamy ) separation.
Mikhail Elia Nasrallah is a plant scientist, specializing in the genetics of self-incompatibility in flowering plants. He is Professor Emeritus in the Plant Biology Section of the School of Integrative Plant Science in the New York State College of Agriculture and Life Sciences at Cornell University. [1]
Her research focuses on plant reproductive biology and the cell-cell interactions that underlie self-incompatibility in plants belonging to the mustard (Brassicaceae) family. [2] She was elected to the US National Academy of Sciences in 2003 for this work and her contributions generally to our understanding of receptor-based signaling in plants ...
Distyly is a type of heterostyly in which a plant demonstrates reciprocal herkogamy.This breeding system is characterized by two separate flower morphs, where individual plants produce flowers that either have long styles and short stamens (L-morph flowers), or that have short styles and long stamens (S-morph flowers). [1]
The morph phenotype is genetically linked to genes responsible for a unique system of self-incompatibility, termed heteromorphic self-incompatibility, that is, the pollen from a flower on one morph cannot fertilize another flower of the same morph. Heterostylous plants having two flower morphs are termed "distylous".
For this reason, most plants have genetic mechanisms to prevent fertilization from pollen grains that are too closely related to the stigma (self-incompatibility). The mechanisms of breeding systems occur at the molecular level through a biochemical reaction on the stigma that recognizes genetic differences in pollen grains.
These small peptide hormones play crucial roles in plant growth and development, including defense mechanisms, the control of cell division and expansion, and pollen self-incompatibility. [58] The small peptide CLE25 is known to act as a long-distance signal to communicate water stress sensed in the roots to the stomata in the leaves. [59]
Late-acting self-incompatibility (LSI) is the occurrence of self-incompatibility (SI) in flowering plants where pollen tubes from self-pollen successfully reach the ovary, but ovules fail to develop. Mechanisms that might cause late-acting self-incompatibility have yet to be elucidated.