The analysis of the bean genes sheds light on the regions of the genome selected during its domestication by humans. These genes are also potential targets for improving its culture, beans being particularly interesting because it fixes atmospheric nitrogen.
The bean is a plant of the family of legumes which, with its different varieties, represents the tenth crop in the world. It is a major source of and essential in some countries: provide up to 15% of and 36% of daily protein in parts of Africa and America.
Historically, common beans were domesticated about 8,000 years ago in two different places: Central America (present-day Mexico) and South America (Andes). Some farmers cultivate three crops: , beans and squash (the “three sisters”). The has led to morphological changes: leaf size and seed of the seed coat, etc.
The goal of work published in was to understand the history of bean domestication to improve modern strains. Indeed, beans are of particular interest to researchers and farmers because of their ability to fix . All require nitrogen for growth, but many agricultural fields are lacking, hence the need for fertilizer. Thanks to the symbiosis that legumes create with a fixing , that of the can be converted into ammonium without the need to enrich the soil with fertilizer.
The domestication of the bean inscribed in its genes
An international team made up of researchers from different universities in the United States but also some French people analyzed the of the common bean, Phaseolus vulgaris . For this, they assembled 473 million base pairs (Mb) of the composed of 11 . Using the sequences of 60 wild and 100 cultivated plants, the researchers confirmed that there were two independent domestications: less than 10% of the 74 Mb involved in domestication were shared by these two large groups of domesticated plants.
Researchers have also identified different , some of which may be useful for improving crops: genes related to increased and seed size, but also those associated with flowering, nitrogen , the to diseases, etc.
Comparing the genome of the bean with that of the , max , also showed that the genome of the bean had evolved more rapidly than that of the . These two would have diverged from their about 19.2 million years ago.