Silicon-microbe symbiosis: redefining plant stress adaptation

Abstract

Increased environmental stresses are among the most limiting factors for agricultural productivity across the world. Reliable and environmentally friendly techniques are needed to sustainably meet growing global food demands. Plant-microbe interactions can alleviate stress, with the application of plant growth-promoting rhizobacteria (PGPRs) that is now widely in use. It has been known that PGPRs enhance plant growth and tolerance to heavy metals by different action mechanisms. Application of silicon (Si) can also stimulate plant growth and heavy metal stress tolerance in plants. Here, we compare the mechanisms, as far as they are known, through which Si and PGPRs can alleviate heavy metal stress in plants. Both alleviate a similar suite of abiotic and biotic stresses, with a few interesting exceptions, though mechanisms differ. The review paper suggests that the combined use of Si and PGPRs can be a powerful and sustainable strategy to enhance plant growth in sub-optimal conditions, and hence, experiments assessing the combined use of Si and PGPRs on plants suffering abiotic and biotic stress can be fruitful in the future.