High water availability in drought tolerant crops is driven by root engineering of the soil micro-habitat

Improving our understanding of drought tolerance of crops is essential in light of future predicted changes in rainfall, decreased groundwater availability, and increasing temperatures. With a focus on above ground traits, significant improvements in drought tolerance of plants has occurred. With such gains plateauing, we have sought to quantify the belowground functional interactions between plant roots and soil in relation to drought tolerance. Using physical, chemical and biological approaches, we compared drought tolerant and sensitive model plants to demonstrate that a tolerant plant alters both the surrounding pore geometry and the relative abundance of bacteria and upregulates the development of a slow wetting rhizosheath, which increases water uptake under drought conditions. We propose that such rhizosheath traits can be targeted to modify the biophysical properties of the rhizosheath to access water in drought conditions.