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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.
Dichogamy: Pollen and stigma of the flower mature at different times to avoid self-pollination. Self-incompatibility: In same plants, the mature pollen fall on the receptive stigma of the same flower but fail to bring about self-pollination. Male sterility: The pollen grains of some plants are not functional. Such plants set seeds only after ...
Specifically these plants exhibit intra-morph self-incompatibility, flowers of the same style morph are incompatible. [3] Distylous species that do not exhibit true self-incompatibility generally show a bias towards inter-morph crosses - meaning they exhibit higher success rates when reproducing with an individual of the opposite morph. [ 4 ]
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".
This selection process relies on gene level regulation in which gene loci of the gynoecium allow either self-pollen to grow slowly, stop growing or burst while faster growth of outcrossed pollen occurs. Self-incompatibility systems maintain genetic diversity. [8] [9] As for gymnosperms, they do not contain a pistil with a stigma. Therefore ...
A controlled fusion of the egg and sperm has already been achieved with poppy plants. [16] Pollen germination, pollen tube entry, and double fertilization processes have all been observed to proceed normally. In fact, this technique has already been used to obtain seeds in various flowering plants and was named “test-tube fertilization”. [17]
Plant species where normal mode of seed set is through a high degree of cross-pollination have characteristic reproductive features and population structure. Existence of self-sterility, [1] self-incompatibility, imperfect flowers, and mechanical obstructions make the plant dependent upon foreign pollen for normal seed set. Each plant receives ...
Outcrossing in plants is usually enforced by self-incompatibility.The primary adaptive function of flowers is the facilitation of outcrossing, a process that allows the masking of deleterious mutations in the genome of progeny.