Priming with the green leaf volatile (Z)-3-hexeny-1-yl acetate enhances drought resistance in wheat seedlings

Various studies showed that green leaf volatiles play vital roles in biotic and abiotic stresses. However, their role in drought resistance has never been studied. In order to investigate the possible role of (Z)-3-hexeny-1-yl acetate (Z-3-HAC, a type of green leaf volatile), various physiology experiments were performed to understand the physiological mechanisms of Z-3-HAC in alleviating wheat drought stress. Drought-resistant wheat seedlings were primed with 100 μM Z-3-HAC at the four-leaf stage before drought treatment. Morphological analysis showed that the primed seedlings grew better and showed higher biomass accumulation in both shoots and roots under drought stress. Additionally, exogenous Z-3-HAC significantly increased the total root length, total root surface area, and total root volume of the seedlings under drought stress. In primed seedlings, physiological measurements showed that the relative water content (RWC), net photosynthetic rate ( P n ), stomatal conductance ( G s ), transpiration rate ( T r ), maximal photochemical efficiency of photosystem II (PSII) ( F v / F m ), photochemical activity of PSII ( F v ′/ F m ′), total chlorophyll content, activities of antioxidant enzymes, and osmolyte accumulation were higher than the control under drought conditions. Furthermore, relative electrolyte conductivity (REC), intercellular CO 2 concentration ( C i ), reactive oxygen species (ROS) accumulation, and malondialdehyde (MDA) content were significantly lower than the non-primed seedlings. Lastly, principal component analysis (PCA) indicated that Z-3-HAC protected wheat seedlings against damage from drought stress mainly through antioxidant and osmoregulatory systems. This study opens a new field of Z-3-HAC application, and provides a new opportunity to improve wheat drought resistance.