Proteomic and Physiological Analyses of dl-Cyclopentane-1,2,3-triol-Treated Barley Under Drought Stress

This study was conducted to determine the effect of exogenous cyclitol (dl-cyclopentane-1,2,3-triol) on barley (Hordeum vulgare L.) during the alleviation of drought stress by using proteomics and physiological approaches. With the relative water content, water potential declined in barley depending on time under drought stress. This decline was lower in cyclitol-treated plants than in untreated plants. The stomatal pore width and open stoma number were higher in cyclitol-treated barley than in untreated plants under drought stress. The abscisic acid (ABA) and proline levels increased with the severity of drought in most treatments. The ABA level was lower in cyclitol-treated plants than in untreated plants under drought stress. Cyclitol treatments reduced O2.-fluorescence in leaf cells under drought stress. Total differentially expressed proteins were identified in cyclitol treatment under stressful and unstressful conditions. Photosynthesis (approx. 49%) and energy metabolism (approx. 27%) were upregulated by cyclitol treatment under drought. Moreover, CML42, acting as a negative ABA regulator, also increased by cyclitol treatment. This increase may be important in controlling stomata movements under drought stress. Our results suggest that exogenous cyclitol enhances the drought tolerance of barley seedlings by modulating the photosynthesis, energy pathway, biosynthesis, and signal transduction.