Some plants need a partner to reproduce. Pollen from one plant pollinates the stigma of another, and a seed is formed. But other plants can self-pollinate, a handy survival mechanism for a lonely plant.
The ability to self-pollinate turns up in cultivated tomatoes and canola, among other important crops, and sometimes it can be a nuisance for plant breeders and seed producers who want to develop highly desirable hybrid varieties and produce hybrid seed on a commercial scale. To get hybrid seed, they plant two different varieties in the same field to allow them to cross-pollinate. But if one or both varieties can self-pollinate, workers must remove the pollen sacs (anthers) from the flowers by hand to prevent "selfing." This is so labor-intensive that it is usually only done in countries where labor is cheap.
Now Cornell researchers are zeroing in on genes that turn a plant's ability to self-pollinate on and off. Their work is described in the May 1 issue of the journal Current Biology and in the journal's online edition.
"The long-term goal is to understand how self-pollination is inhibited in self-incompatible plants, which are unable to self-pollinate because their stigmas can recognize and reject their own pollen. Then you could transfer this ability to any plant and use it to make hybrids," said June Nasrallah, the Barbara McClintock Professor of Plant Biology at Cornell.
Nasrallah's research group is working with Arabidopsis thaliana , a plant related to cabbage and mustard that is widely used in plant genetic research and whose genome has been sequenced. Previously, the group showed that two genes known as SCR and SRK are the key to self-incompatibility. SCR codes for a protein on the surface of pollen grains, and SRK codes for a receptor in the cell membranes of stigma cells. When these two proteins come from the same plant, the stigma rejects the pollen, and fertilization does not occur.
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26-Apr-2007