Inactivating Genes Boosts Crop Genetic Diversity

Researchers from the Agricultural Research for Development (CIRAD) and National Institute for Agricultural Research (INRA) in France recently showed that inactivating a gene, RECQ4, leads to a three-fold increase in recombination in crops such as rice, pea, and tomato. The gene was found to inhibit the exchange of genetic material via recombination (crossover) during the sexual reproduction process in crops. This discovery could speed up plant breeding and development of varieties better suited to specific environmental conditions (disease resistance, adaptation to climate change).

Recombination is a natural mechanism common to all organisms that reproduce sexually. The chromosome mix determines the genetic diversity of species. The plant breeding practiced for the past 10,000 years involved crossing two plants chosen for their complementary worthwhile characters. For instance, to obtain a new tomato variety that is both tasty and pest- or disease-resistant, breeders cross and breed, via successive recombinations. However, this is a lengthy process, as very few recombinations occur during reproduction. To find out what limits the number of recombinations, researchers from INRA identified and studied the genes involved in controlling recombination in Arabidopsis. They discovered that one gene, RECQ4, is particularly effective at preventing crossing-over. Researchers examined three agriculturally valuable species: pea, tomato, and rice, and they succeeded. They found that by "switching off" RECQ4, they trebled, on average, the number of crossovers, resulting in greater chromosome shuffling, hence increased diversity, with each generation.

More details are available in the news article from CIRAD.