19. Self-Pollination
June Nasrallah
June B. Nasrallah, Plant Biology, and her research group extended their findings on genes that turn a plant’s ability to self-pollinate on and off. Cultivated tomatoes and canola are among crops with the ability to self-pollinate. To get hybrid seeds, plant breeders and seed producers plant two different varieties in the same field to allow them to cross-pollinate. If one or both varieties can self-pollinate, workers must remove the pollen sacs from the flowers by hand. This is a labor-intensive and costly process for developing hybrid varieties and producing hybrid seeds on a commercial scale. Working with Arabidopsis thaliana, a cabbage relative, Nasrallah’s group previously showed that two genes known as SCR and SRK are the key to self-incompatibility. Working with the highly self-fertile A. thaliana and the self-incompatible A. lyrata, the researchers created A. thaliana varieties that could not self-pollinate or had only a limited ability to self-pollinate (pseudo self-compatible). The study mapped the genomes of several varieties of transgenic A. thaliana and isolated a gene known as PUB8 that seems to regulate whether or not SRK is turned on to manufacture its protein. Nasrallah’s team concluded that pseudo self-compatibility is a best-of-both-worlds mating strategy, because it maintains the benefits of cross-pollination while providing reproductive assurance when mates or pollinators are scarce. The researchers’ goal is to understand precisely 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. Plant breeders may then be able to transfer this mechanism to any plant as they create hybrids.