Effects of calcium inhibitors on reactive oxygen species metabolism in poplar leaves under mechanical damage stress.

With one year old poplar(Populus simonii×P.pyramidalis cv.'Opera 8277') as materials,the effects of Ca2+ channel blockers LaCl3 and Ca2+ chelator EGTA on antioxidant enzymes activities,H2O2 and MDA contents,and O-·2 producing rate in poplar leaves under mechanical damage stress were studied.The results showed that the activities of SOD,POD,CAT and APX were significantly higher than those of control;the contents of H2O2 and MDA and producing rate of O-·2 were obviously increased in poplar leaves treated by mechanical damage.Exogenous EGTA and LaCl3 application on the leaf remarkably reduced the activities of SOD,POD,CAT and APX,slowed down the producing rate of O-·2,the contents of H2O2 and MDA were decreased;And the inhibition of EGTA was stronger than that of LaCl3.The results suggested that the metabolism of active oxygen species induced by mechanical damage stress need the participation of Ca2+.Ca2+ and active oxygen species were closely related in plant defense signal transmission;extracellular Ca2+ influx induced by damage was an important source of the increasing of intracellular Ca2+ concentration.The damage induced Ca2+ flowed into cells and increased Ca2+ concentration in cells.