Potential advantage of rhizosheath microbiome, in contrast to rhizosphere microbiome, to improve drought tolerance in crops

Drought stress-single or in combination with abiotic and biotic stresses-is a major constraint on agricultural production and threatens food security worldwide. This has further led to the need for some environmentally friendly approaches to ensure global food security. In this regard, using the potential of drought tolerant-plant growth-promoting microorganisms to minimize the effects of drought stress is an important effort. It seems that the microorganisms that live in plant rhizosheaths, which are preferentially formed in drier soils, have a higher potential to alleviate drought stress and enhance plant productivity compared to the microorganisms isolated from plant rhizosphere. By some known mechanisms, these microorganisms not only ensure the survival of plant under drought stress but also augment the plant growth. Here, the importance of rhizosheath and its microbiome in improving plant drought tolerance and also its importance as a useful source for isolating drought-tolerant microorganisms with plant growth promotion potential are highlighted. Future directions to the study of the rhizosheath microbiome are also suggested. The knowledge on rhizosheath microbiome is essential for developing strategies for shaping the rhizosheath to benefit drought-stressed plants.