Plant self-incompatibility

Unilateral incompatibility is a phenomenon in which self-compatible species can be crossed as a female, but not as a male, to self-incompatible species (Abdalla and Hermsen, 1972). Pollen tubes fail to penetrate stylar tissue in self-incompatible (female) X self-compatible (male) crosses. Although most diploid Solarium species are self-incompatible, the Mexican species S. verrucosum is self-compatible. Dinu et al. (2005) found that S. verrucosum could be crossed as a female, but not as a male, to self-incompatible species. It is sometimes possible to find exceptional plants that do not exhibit unilateral incompatibility in self-incompatible X selfcompatible interspecific crosses (Pandey, 1962). The identification of such plants allows a breeder to overcome the unilateral incompatibility crossing barrier. For example, exceptional plants ( acceptors ) that accept S. verrucosum pollen and produce fertile hybrids have been reported (Eijlander et al., 2000). It is interesting that some acceptor plants will accept pollen... 

Variations of the life cycle occur. For example, a process called apomixis leads to asexual formation of seed.469 In many plants, including maize, separate flowers form the ovule and the pollen. This is one mechanism for avoiding inbreeding.470 In many plants systems of self-incompatibility have evolved.471 In some, e.g., Arabidopsis and other crucifers, pollen germination is disrupted unless it falls on a stigma possessing a different allele-specific receptor. In other cases development of the pollen tube is disrupted at a later stage. In maize and in more than 150 other... 

CUI, Y. H BRUGIERE, N JACKMAN, L SI, Y. M., ROTHSTEIN, S. J., Structural and transcriptional comparative analysis of the S locus regions in two self-incompatible Brassica napus lines., Plant Cell., 1999,11, 2217-2231. 

Chestnut trees are typically monoecious, but chestnut is self-incompatible, which makes cross-pollination a necessity for crop production. Recognition of the incompatible and compatible strains in an early stage of development is essential for the planting of economically valuable chestnut gardens. 

Cross-fertilization in plants. This promotes genetic variation in the population especially in plants that are dioecious and monoecious. Most plants are hermaphrodite, but have mechanisms such as self-incompatibility that promote allogamy. 

Gibbs, R, Self-incompatibility in flowering plants a neotropical perspective, Revisto Bras//. Bot., 13,125,1990. 

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