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.