Symbol of our agricultural identity, Mediterranean olive trees are put to the test by drought. But the answer could come from underground. An ENEA research team, in collaboration with the Cnr and the universities of Milan, Turin and Tuscia, has identified “tailor-made” microbial communities that strengthen the ability of olive trees to resist water shortages.
The study, published in the journal Applied Sciences, analyzed the soil and root microbiome of four olive cultivars grown in Umbria, subjected to irrigation and water stress conditions. “The olive tree was chosen as a model species to develop an innovative cultivation system, representative of Mediterranean agriculture threatened by climate change,” explained Gaetano Perrotta, researcher at the ENEA Laboratory of Circular Regenerative Bioeconomy, in a note.
The researchers studied the rhizosphere, the area of soil surrounding roots, to understand how microbes react to drought. “In the soil the microbial composition remains rather stable, but in the roots the plant selects the bacteria that offer it an adaptive advantage,” underlines Andrea Visca, ENEA biotechnologist.
The analysis revealed a “core microbiome” – a stable group of fundamental microbial species – with three protagonists: Solirubrobacter, Microvirga And Pseudocardia. The first promotes the decomposition of organic matter and the cycle of nutrients, the second helps plants absorb nitrogen, the third produces antimicrobial substances that defend the roots from pathogens.
When water is scarce, these bacteria activate genes that enhance nutrient use and protect cells from oxidative damage, improving plants’ ability to adapt. “The interface between roots and rhizosphere is crucial for the health and development of plants”, underlined Annamaria Bevivino, of the ENEA Sustainable Agri-Food Systems division.
To investigate these invisible interactions, the team combined DNA analysis, functional study of microbial communities and text mining, a method that analyzes thousands of scientific articles to identify connections useful for research. Thanks to this integrated approach, it was possible to identify over 1,200 microbial species involved in adaptation processes, and distinguish the functional groups responsible for nutrient recycling and protection against oxidative stress.
The study shows that, even in conditions of prolonged drought, soil microbial biodiversity can remain surprisingly stable thanks to “functional redundancy”: different microorganisms perform the same function, thus ensuring a sort of ecological insurance. An important discovery for those who study the adaptation of Mediterranean crops to climate change.
These results pave the way for new agricultural practices based on selected microbial consortia, capable of improving the yield and resistance of plants without resorting to chemicals. “The integrated approach of culturomics and metagenomics will allow us to develop increasingly sustainable and regenerative solutions,” concluded Bevivino.
The next step, according to ENEA, will be to test these microbial consortia directly in the field, evaluating their effectiveness on a large scale and in different climatic conditions. If the results are confirmed, the olive groves of the future could count on a new invisible ally, capable of transforming the soil into a strategic resource for the agricultural resilience of the Mediterranean.
