“Salt is quietly destroying farmland. It builds up through irrigation, creeps in from rising seas, and accumulates faster as the climate warms. 

Hundreds of millions of hectares are already affected worldwide, and the problem is getting worse. Plants, generally speaking, don’t handle salt well. 

But a new study has found that certain soil bacteria do something unexpected when salt stress hits: they show up at plant roots, trigger a chain of biological changes, and make crops significantly more resilient…

What the team found, across multiple crops and multiple soil types, was a consistent pattern. A group of bacteria called pseudomonads kept appearing at plant roots specifically under salt stress…

To test whether the bacteria actually helped, the researchers introduced pseudomonad strains into soybean plants and watched what happened. 

The bacteria colonized the roots. The plants, in both greenhouse conditions and real field trials, grew better – stronger roots, better development, higher yields – than untreated plants in the same salty soil.

The assumption in the field for decades was that plants manage salt stress primarily by controlling sodium, keeping harmful ions out of sensitive tissues and maintaining the chemical balance needed for normal function…

What the bacteria were actually triggering was the production of lignin. If you’ve ever wondered what makes wood hard, lignin is the answer – it’s the structural polymer that reinforces plant cell walls and gives them rigidity and toughness. 

In bacteria-treated plants under salt stress, lignin content in the roots increased significantly, in some cases by more than 30 percent.”

From Earth.com.