Mitigation of PEG-Induces Drought Stress in Wheat (Triticum durum) by Exogenous Application of Proline

Drought is considered one of the most important environmental stresses that has serious limitations on production of most crop plants, including wheat. Proline is an amino acid closely associated with plant responses to environmental constraints. This research aims to study the response of four varieties of durum wheat (Triticum durum) subjected to water stress stimulated by polyethylene glycol (20% PEG-6000) which is equivalent to osmotic potential of -1.2 Mpa. A total of 4 wheat genotypes were grown hydroponically and four treatments were imposed. Wheat plants exposed to drought stress showed reduced growth, which was correlated with reduced relative water content, chlorophyll content and stomatal conductance as evidenced by principle component analysis (PCA). It also revealed that electrolyte leakage and malondialdehyde (MDA) accumulations were closely related with the declined growth and wheat plants development under drought stress. Importantly, application of 6 mM of exogenous proline improved the growth responses of wheat plants to drought stress. Proline strengthened numerous physio-biochemical processes coupled with decreasing in MDA levels which indicates successful adaptation of wheat plants to drought stress. The results of PCA strongly supported that application of proline in stressful conditions ameliorated the responses of wheat mostly by enhancing physiological and biochemical activities. Eventually, it can be concluded that proline supplementation is one of the useful approaches to alleviate the adverse effects of water stress on wheat crop.