Salinity represents a big abiotic threat to global agricultural sustainability. Na+ accumulation in plants significantly reduced stomatal conductance and wheat crop yield. However, the regulatory networks underlying Na+ induced stomatal kinetics changes remain unclear. Here, we investigated stomatal morphological and physiological responses using two wheat cultivars, SaltY055 (salinity tolerant) and Salty 038 (salinity susceptible), upon long- and short-term salinity treatment to dissect the stomatal regulatory networks underlying wheat salinity tolerance.

Long-term salinity (150 mM salt in soil) led to reduced stomatal conductance but enhanced stomatal sensitivity to exogenous abscisic acid (ABA) in Salty055. Feeding the wheat roots transiently with 150 mM NaCl significantly enhanced stomatal closure and reduced stomatal response time only in SaltY055. Additionally, sorbitol failed to induce same amount of stomatal closure in both cultivars, excluding the osmotic stress from 150 mM NaCl treatment.

Further molecular investigations suggest that differences in salinity tolerance among cultivars are highly linked with expression levels of genes involving ABA biosynthesis, ROS metabolites and ion channel activities. Our research adds evidence to understand Na+ derived stomatal regulations, offering clues in screening germplasm and speeding up breeding of crops for salinity tolerance.