Pollen compatibility

Remarkably, Brassica napus pollen was reported to have a 22 kDa cutinase that cross-reacted with antibodies prepared against F. solani f. pisi cutinase [134]. Although a 22 kDa and a 42 kDa protein that catalyzed hydrolysis of p-nitrophenyl butyrate were found in this pollen, only the former catalyzed cutin hydrolysis. Immunofluorescence microscopic examination suggested that the 22 kDa protein was located in the intine. Since the nature of the catalytic mechanism of this enzyme has not been elucidated, it is not clear whether this represents a serine hydrolase indicating that plants may have serine and thiol cutinases. The role of the pollen enzyme in controlling compatibility remains to be established. 

In many plant species compatible pollen tubes grow directly down inside the style as a bundle of long smooth tubes with bright callose plugs. Only in female sterile plants of Oenothera mut. brevistylis was branching of pollen tubes found in the style and ovary (7). 

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... 

Luu, D. T., Qin, X., Morse, D., Cappadocia, M. (2000). S-RNase uptake by compatible pollen tubes in gametophytic self-ineompatibility. Nature, 407, 649-651. 

Gene flow The movement of genes from one population to another by way of hybridization of related and sexually compatible individuals in the two populations. In plants, gene flow takes place by transfer of pollen (male gametes) or seeds. 

Tupy, J. Changes in glucose and fructose level in Nicotiana alata styles and ovaries accompanying compatible and incompatible pollen tube growth Biol. Plantarum 3 (1961) 1-14. 

Pollination is the natural way for most plants to spread their genetic information, make up new plants, and to deliver their offspring in other locations. The use of plants with Kmited range of pollen dispersal and limited contact with compatible wild hosts therefore is also very effective to prevent genetic drift. Corn, for example, has pollen, which survives for only 10 to 30 min and, hence, has an effective fertilizing radius of less than 500 m. In North America, it has no wild-type relatives... 

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