根系渗透胁迫时杨树光合作用光抑制与活性氧的关系

为更多地了解自然条件下活体叶片的光抑制，研究了渗透胁迫时杨树无性系幼苗叶片的光抑制与活性氧代谢的关系．结果表明，随胁迫时间的延长和胁迫强度的增大，杨树叶片O2^-生成加快，H2O2和丙二醛(MDA)含量增多，超氧物歧化酶(SOD)活性升高，过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性降低，活性氧代谢失衡，光合作用的光抑制加剧．用二乙基二硫代氨基甲酸铜盐抑制SOD活性，或用甲基紫精加速O2^-的生成，亦可使杨树叶片发生光抑制．渗透胁迫时杨树无性系幼苗清除H2O2能力降低，限制了叶片通过Mehler反应耗散过剩光能，防御光破坏作用的发挥；光抑制的发生与活性氧的积累有关．

Relationship between photo-inhibition of photosynthesis and reactive oxygen species in leaves of poplars suffering root osmotic stress

To know more about the photo-inhibition of photosynthesis under field conditions, its relationship with reactive oxygen species (ROS) in leaves of poplar clone seedlings was studied under osmotic stress conditions. With the increasing duration of osmotic stress and the enhancement of stress intensity, the ROS level, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity increased, while the activities of catalase (CAT) and ascorbate peroxidase (APX) decreased, resulted in the unbalanced ROS metabolism and intensified photo-inhibition. The inhibition of SOD activity by copper diethyldithiocarbamate or the accelerated generation of O2-. with methyl viologen (MV) could also induce the photo-inhibition. The decrease of the ability of poplar clone seedlings in scavenging H2O2 under osmotic conditions limited the dissipation of excess light energy and the role of photosynthetic apparatus in protecting against photo-inhibition through Mehler reaction. Photo-inhibition might be related to the accumulation of ROS.