Methyl Jasmonate Impact On The Physiological Role Of Cotton Under Water Stress

Effects of Methyl Jasmonate on Physiological Roles of Cotton Seedlings under Water stress Abstract Two different drought resistant cotton cultivars, drought resistant cultivarJin-mian2l and drought susceptible Taill, were used in the experiment. After the treatment of methyl jasmonate, the effects of the various osmotic stresses induced by PEG (0.3mmol/L, 0.5 mmolIL, 0.7mmol/L, O.9mmol/L) on the defensive enzymes activities of superoxide dismutase (SOD) and peroxidase (POD), water potential, osmotic potential, photosynthetic rate, stomatal conductance, membrane permeability and result of membrane lipid peroxidation, malondialdehyde (MDA) and the content of proline in the cotton seedling were studied. In addition, the different droughts of two cultivars were compared. The results of the experiment showed that the responses of the two cotton varieties to osmotic stress were different. Under water stress, Jin-mian2l, drought resistant variety, had a slower decline rate in water potential and a more negative osmotic potential, compared with the drought susceptible Taill. Therefore, Jin-mian2l leaves could maintain a higher turgor potential. With the stress strengthening, Jin-mian2l accumulated much more proline than Taill, displaying a higher osmotic adjustment capacity. Under osmotic stress, there was a negative correlation of the activities of defensive enzyme systems such as SOD and POD with the level of membrane lipid peroxidat ion and the permeability of plasma membrane. It is suggested that these parameters may be used as important indexs for breeding drought resistant cotton. The experiment results showed that JA-Me can increase water potential and osmotic potential under the different water stresses in cotton seedling of two varieties. After the treatment of JA-Me, the content of proline and the activities of SOD and POD were higher than non?treatment, moreover, there were different between the varieties. And JA-Me can decrease the accumulation of MDA in leaves of cotton seedling under water stress. Consequently, JA-Me can increase the activities of defensive enzymes and reduce the degree of membrane lipid peroxdation in cotton; meanwhile, JA-Me can protect the intactness of membrane structure and decrease the hurt of water stress.