Changes Of Ca～(2+) And Ca～(2+)-ATPase Activities In Cells Of Populus Euphratica And P. Euramericana Under Stress

The studies on plant resistance mechanism in cellular level under salt stress and drought stress mainly focus on herbaceous plant,but fewer on woody plant. This study used leaf cells of a salt-resistant poplar genotype Populus euphratica and salt-sensitive genotype P. euramericana to examine the changes of intracellular Ca²⁺ distribution, the vacuole Ca²⁺ level and the activity of Ca²⁺-ATPase in plasma membrane and tonoplast membrane of Populus euphratica and P. euramericana under salt stress and drought stress through an electron microscopic-cytochemical method in cellular level.The study showed that in the aspects of the changes of intracellular Ca²⁺ distribution and vacuole Ca²⁺ level, Populus euphratica and P. euramericana had the same reaction to adversity stresses. The vacuole Ca²⁺ level of both polar decreased with the strengthening of stresses, which is consistent with the results of studies on herbaceous plant under stresses. The activity of Ca²⁺-ATPase in plasma membrane and tonoplast membrane of the two polar are different under drought stress. To P. euramericana, it decreased with the increasing of the duration of drought stress, while to Populus euphratica, it increased first and then decreased. The activity of Ca²⁺ -ATPase in plasma membrane and tonoplast membrane of Populus euphratica kept higher than that of P. euramericana with the same treatment. And it was the same case under salt stress, that is to say, the activity of Ca²⁺-ATPase in plasma membrane and tonoplast membrane of Populus euphratica decreased after it increased, while for P. euramericana, it kept decreasing with the increasing of strength and duration of salt stress.