Researchers One Step Closer to Developing Apomictic Crops

Scientists worldwide are pursuing apomixis as a powerful tool to create hybrids that produce generation after generation of seed that retains its vigor and produces plants identical to the mother plant. Apomixis occurs naturally in more than 400 plant species but is rare in important crops such as rice, wheat and corn. Scientists from France's National Scientific Research Center (CNRS), French National Institute for Agricultural Research (INRA) and Research Institute in Molecular Pathology in Austria, made an important breakthrough in developing apomictic crops. The team addressed an important hurdle in apomixis research: meiosis. Meiosis is the type of cell division that produces male and female gametes with a mix of parental traits. Using a combination of three genetic mutations in the plant model Arabidopsis, the research team created a genotype they called MiMe in which meiosis is completely replaced by mitosis or asexual cell division.

Raphaël Mercier and colleagues targeted three processes unique to sexual cell division:

• recombination or the paring of chromosomes using mutation in the Atspo11-1 gene
• segregation or the separation of the chromosome pair using mutation in the Atrec8 gene
• and the second round of cell division using mutation in the osd1 gene

However, achieving apomixis is still a distant goal. Experts predict that apomictic crops may still be 15 years away from being available in the market. The downside of replacing meiosis with mitosis is that the chromosome number increases with each generation. Fertility drops as the chromosome number rises. Scientists must also find a way to produce viable seeds with fertilization, a process called parthenogenesis. Nonetheless, scientists worldwide have recognized the importance of the discovery by Mercier and colleagues.

The open-access paper published by PLoS ONE is available at http://dx.doi.org/10.1371/journal.pbio.1000124 A summary of the research paper is available at http://dx.doi.org/10.1371/journal.pbio.1000118 Nature published a feature article on the research. It is available to subscribers at http://dx.doi.org/10.1038/news.2009.554