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Source: Biotechnology and Biological Sciences Research Council (BBSRC)

Scientists at the University of Birmingham have uncovered how the field poppy prevents self-pollination, a form of inbreeding that if unchecked would result in a shrinking gene pool and unhealthy offspring. The researchers, led by Professor Vernonica Franklin-Tong, have found that the poppy use a common 'enzyme switch', phosphorylation, as one of its key weapons to prevent self-pollination. The work is a significant step in understanding a key mechanism in plant biology and could provide a major boost for plant breeders.

Most flowering plants run the risk of pollinating themselves, rather than receiving pollen from another plant via an insect. The basic anatomy of many plants means pollen sacs are situated right next to the female reproductive parts. Accidental self-fertilization is a real risk. When a flowering plant is pollinated the pollen germinates and develops a pollen tube which grows through the stigma and female tissues and then enters the plant's ovary to effect fertilization. The Birmingham team, funded by the Biotechnology and Biological Sciences Research Council (BBSRC), has found that when genetically identical pollen comes into contact with the field poppy's stigma, it triggers several chemical signals for inhibiting growth of the pollen tube. With tube growth halted fertilization cannot take place.

By adding phosphate to key enzymes involved in pollen tube development the plant effectively stops the pollen tube from growing, explains Professor Franklin-Tong at the University's School of Biosciences.

"Most plants require pollen from another plant to successfully pollinate. Accidental self-pollination would lead to unhealthy and less successful offspring. To avoid this plants need robust ways to stop self-pollinating activity," says Franklin-Tong.

"Our research has found that the field poppy has developed a particularly successful way of doing this. Pollen tubes require high metabolic activity, so inhibiting a key enzyme involved in driving these "high metabolism" processes is a very successful way of stopping pollen tube growth."

A better understanding of plant mechanisms against self-pollination could improve plant breeding. The possibility of selectively switching the self-pollination control on or off could make it much easier and cheaper to produce hybrid plants and seed.

Professor Franklin-Tong comments: "At the moment plant breeders must use expensive and time-consuming manual techniques to ensure new strains of plants do not self-pollinate. This is to ensure the traits they want come from both parent plants. If we could switch on the mechanism to guard against self-pollination we could drastically reduce the cost and time of developing new plant varieties."

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