Grafting Raises the Cu Tolerance of Cucumber Through Protecting Roots Against Oxidative Stress Induced by Cu Stress

摘要

cqvip:A greenhouse experiment was carried out to determine plant growth,reactive oxygen species(ROS) metabolism in roots and functions of plasma membrane(PM) and tonoplast in cucumber seedlings(Cucumis sativus L.cv.Xintaimici) treated with 40 μmol L-1 CuSO 4.5H2O,which were either ungrafted or grafted onto the rootstock(Cucurbita ficifolia).Cu treatment inhibited growth,induced significant accumulation of H2O2 and led to serious lipid peroxidation in cucumber roots,and the ROS-scavenging enzymes activities in grafted seedlings roots were significantly higher than that of ungrafted plants,thus less accumulation in grafted cucumber roots induced by Cu.As a result,lipid peroxidation in roots decreased.Furthermore,the activities of H+-ATPase,H+-PPase and Ca2+-ATPase in PM and/or tonoplast in grafted cucumber seedlings under Cu stress were obviously higher than that in ungrafted plants,resulting into higher ability in grafted plants to expulse the excess H+,promote the cytoplasm alkalinization,regulate the intracellular Ca2+ concentration and brought the cytoplasma concentration of free Ca2+ to extremely low level under Cu stress.