Can interaction between silicon and plant growth promoting rhizobacteria benefit in alleviating abiotic and biotic stresses in crop plants?

Increased environmental stresses are among the most limiting factors for agricultural productivity across the world. Reliable, environmentally friendly techniques are needed to sustainably meet growing global food demands. Some 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 plant tolerance to biotic and abiotic stresses by different action mechanisms, often more than one mechanism. Application of silicon (Si) can also stimulate plant growth and alleviate an array of biotic and abiotic stresses in plants. In addition, Si is not detrimental to plants and, depending on application method, can be free from pollution even when applied in excess. Here, I compare and contrast the mechanisms, as far as they are known, through which Si and PGPRs can alleviate abiotic and biotic stresses in plants. Both alleviate a similar suite of abiotic and biotic stresses, with a few interesting exceptions, though mechanisms differ. I suggest 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.