Root colonizing microbes associated with notable abiotic stress of global food and cash crops

Abstract

The increase in cash crop productivity has helped improve farmers, communities, and economic streams and has served as a source of income. However, the erratic global climate change deeply affects crops' productivity due to the exacerbating high temperatures predominant in some geographical regions, which has translated into other environmental issues. Combinatorial impacts of these climate-associated problems have exposed agricultural lands to multiple abiotic stresses, placing massive pressure on cultivatable arable lands and reducing crop productivity. Agronomists, through an understanding of single abiotic stressors, have innovated new concepts like nanotechnology, molecular modified and cross-bred varieties to unravel these problems. However, the complexity, toxicity, and resistance development associated with these approaches have consistently left the search window open for novel, natural, and more sustainable alternatives. To this end, the roles of root microbiomes, particularly root endophytes, in ensuring plant growth promotion through siderophore production, phytohormone release and regulation, and nutrient fertilization have been harnessed in an effort to resolve single, double, and multiple abiotic stressors without a complete understanding of the pathways involved in each mechanism of plant growth promotion. Thus, to successfully leverage root endophytes for growth promotion during multi-stresses, this review is targeted to reveal single abiotic stress mechanism for each cash crop group, as this could help conceptualize the details involved in stress control and the alleviation of multi-stresses through nutrient fertilization pathways.