The Activation and Regulation of Ca-CaM Signaling System on the Activity of Ca²+-ATPase and H+-ATPase In Leaves of Longan Under Stimulated Acid Rain Stress

Longan (Dimocarpus longana Lour. cv. Wulongling) of uniform one-aged seedlings grown in pots were selected to study the activation and regulation of Ca-CaM signalling system on the activity of Ca²⁺-ATPase and H⁺-ATPase in leaves of longan under stimulated acid rain stress and its exogenous Ca²⁺ regulation. The results showed that the content of calmodulin (CaM) was influenced by the intensity and duration of simulated acid rain. The CaM content fluctuated during stress, but the fluctuating scope decreased gradually while stress duration prolonged. The activities of H⁺-ATPase and Ca²⁺-ATPase were also influenced by stress intensity and duration. Both of Ca²⁺-ATPase and H⁺- ATPase in leaves were very sensitive to acid rain, and their activities were significantly inhibited under the acid rain stress of pH 3.5 and pH 2.5.The CaM content, activities of Ca²⁺-ATPase and H⁺-ATPase in leaves were activated by spraying 10 mM Ca²⁺, and reduced by spraying calmodulin inhibitor chlorpromazine (CPZ) with concentration of 2 mM, and the calcium inhibitor EGTA with 5 mM.