Clonal reproduction closer than ever

Clonal reproduction of crop species took a step closer to being realised with new research published in PLoS Biology this week. The paper blurs the line between meiosis and mitosis by showing a plant where three specific mutations are experimentally combined. These divisions are normally meiotic - which make pollen and egg cells - and are replaced by mitotic divisions.

The work, by a team of researchers in France and Austria, is potentially very important commercially because it makes the creation of stable new mutant crops - such as plants of a different colour, or with a different yield - much simpler. It is now much closer to being possible to reproduce a plant that produces perfect potatoes, maize or rice, without the lottery of reassortment that each meiotic division and ensuing fertilization introduces.

The new work, led by Raphael Mercier, identifies a gene that controls entry into the second meiotic division in the sexual plant Arabidopsis thaliana. By combining a mutation in this gene with two other previously described mutations - one that eliminates recombination and another that modifies chromosome segregation - the authors have created a strain of plant (called MiMe for 'mitosis instead of meiosis') in which meiosis is totally replaced by mitosis.

MiMe plants produce pollen and eggs that are genetically identical to their parent. If MiMe eggs are self-fertilized by MiMe sperm, the offspring plant has twice as much DNA as the parent generation, and has all the genes from this single parent. Thus the authors have made a form of asexual reproduction possible in a normally sexual species.

Turning meiosis into mitosis is not enough to reach clonal reproduction, but it's a giant leap towards it. This has potential revolutionary applications in crop improvement and propagation.