These are the microbes that shaped the green bean

In parallel with the domestication of plants, there was also a selection of their microbiota. Except that the latter was done without our knowledge. An in-depth study on green beans has just demonstrated that the selected traits actually depended a lot on the population of bacteria, viruses and fungi that each plant harbors within it.

Hervé Poirier, editor-in-chief of the scientific magazine Epsiloon explains to us today that by domesticating plants, the first farmers, without knowing it, actually selected the microbes that live with them. Enough to rethink agriculture too accustomed to pesticides.

franceinfo: Each plant harbors bacteria, viruses and fungi?

Hervé Poirier: This is the case for beans. More precisely for the green bean, domesticated 9000 years ago in the Andes, and for the white bean, cultivated 1000 years later. Researchers have recovered cultivated seeds from these two species, as well as wild relatives, from the Andes and Central America. They grew them in a greenhouse.

Then, using genetic sequencing tools, they analyzed the populations of bacteria that these plants harbor, in the roots, stems and seeds. They then showed that green and white beans attract and promote a bacterial population very similar, but very different from their wild cousins. And that these bacteria played a discreet, but essential, role in the development of agriculture.

Because these bacteria have a real influence on the quality of the beans?

Yes. Researchers have shown this for calcium. It is known that domesticated plants have less calcium than wild ones: this makes them less hard to the bite and easier to cook. However, the populations of bacteria specifically recruited by green beans play a key role in this calcium content.

By selecting plants for this culinary and taste quality, the first Andean farmers therefore, without knowing it, indirectly selected populations of specific bacteria. If green beans are so good, it’s thanks to them! The same is very likely true for other key characteristics (size, precocity, yield, resistance, etc.). As well as other domesticated plants (corn, rice, wheat, etc.). Unbeknownst to them, farmers have always been microbiologists.

Which questions the use of pesticides in agriculture…

Yes. Agriculture, and biology in general, have long tended to be interested only in the intrinsic characteristics of species, independently of their interaction with the environment. This work is more generally part of the awareness of the importance of microbiota within plants and animals.

No, living things are not a collection of separate individuals. It is above all woven by networks of alliances, partnerships and symbioses. It’s a fundamental movement. The science of life becomes the science of relationships. Biology becomes ecology.