Physiological mechanisms preventing plant wilting under heat stress: a case study on a wheat (Triticum durum Desf.) bound water-mutant

Wilting is the main symptom of plants suffering the dehydration stresses, but the mechanisms governing this phenomenon are yet to be completely understood. In this work, a holistic analysis of physiological traits potentially involved in leaf wilting was performed, comparing a wheat wild type (WT), Trinakria and its water-mutant (WM) with a “high affinity for bound water (BW)”. In addition to the tendency to wilt, significant differences between genotypes were observed for leaf temperature achieved under heat stress, leaf turgor loss with decreasing water potential, cuticular transpiration, and Q10 of leaf water uptake velocity. We hypothesize that mutant plants prevent the increase in leaf temperature thanks to the rapid and low energetic cost of water diffusion from the vessels to the outside, driven by the BW. Under strong thermal-induced dehydration stress, BW delays leaf wilting through its positive effects on cell wall elasticity and passive osmoregulation.