Exploring the coordinated hydraulic plasticity across organs in soybean plants exposed to drought cycles

Abstract

The coordination of hydraulic function among different organs and their plasticity under stressful conditions are crucial for understanding drought tolerance in crops but remains poorly understood. Here, we evaluate the hydraulic plasticity in soybean organs exposed to one or two droughts and correlated this plasticity with recovery after rewatering. Repeated drought events resulted in different levels of dehydration in soybean leaves since plants exposed to two droughts (D2 plants) maintained higher water potential than plants exposed to a single drought (D1 plants). The difference in leaf water potential reflected the different drought acclimation strategies in D1 and D2 plants. D1 plants increased root hydraulic conductance, a change that can occur rapidly due to molecular modifications. The first drought also acted as an environmental cue, triggering changes that continued to develop over time (anatomical changes) and which increased water transport in the stem of D2 plants, reducing the drought impact in these organs and maintaining the water transport to the leaves. Leaves of D1 and D2 plants, in turn, reduced vulnerability to embolism, avoiding losses in rehydration capacity and helping to maintain the hydraulic functions essential for the rapid recovery of photosynthesis after rewatering.