“To make a seed it takes a fruit,” pupils use to sing in Italy. Then students learn that there is an embryo inside seeds and it takes a pollen fertilized egg to make it. The dream of plant scientists, however, has always been to be able to produce seeds using only the cell egg. This dream has finally come true: a group led by Venkatesan Sundaresan, at UC Davis, has developed a rice variety capable of cloning its seed.
To switch this kind of asexual reproduction, called apomixis, they over-expressed a gene called Baby Boom1, triggering the initiation of embryogenesis without fertilization. Then they used CRISPR to knockout three genes, disabling the division process typical of germ cells as a result. This second step, called MiMe, substitutes mitosis for meiosis and was discovered in France by one of the paper co-authors. Please read the Nature paper and the UC Davis press release for the details.
Far from being a mere botanical curiosity, the accomplishment is a giant leap forward the future of agriculture. Some 400 kinds of plants naturally self-clone their seeds, dandelions for example, while agronomically important crops reproduce only by sex. Turning rice, corn, sorghum, etc asexual is a highly desirable goal. It will help breeders, by making the genetic improvement process faster and easier, and could greatly benefit farmers, by allowing direct reseeding. Apomixis is set to be a game changer for developing countries, as poor farmers could share new, high performing seeds with their neighbors and replant from their own harvest year after year.