摘要
The effects of salt stress on photosynthesis,Mehler-peroxidase reaction(MPR)and the susceptibility of PS ll to photoinhibition were investigated in Rumex K-1 leaves.Salt stress resulted in dramatic decrease in photosynthesis,but had no significant effect on maximal photochemistry of PS ll(Fv/Fm).During photosynthetic induction,a considerable electron flow was transported to oxygen in MPR both in control and salt-stressed leaves.Under steady state photosynthesis,enhanced electron flow to oxygen in MPR was observed only in salt-stressed leaves.The enhanced MPR in salt-stressed leave was accompanied by enhanced activities of scavenging enzymes,i.e.superoxidase dismutase(SOD)and ascor-bate peroxidase(APX).In the presence of saturating CO_(2).decreasing oxygen concentration from 21%to 2%did not affect the susceptibility to photoinhibition in control leaves,but largely increased the suscep-tibility to photoinhibition in salt-stressed leaves.Based on these results,it is concluded that the enhanced MPR in salt-stressed Rumex leaves serves as a sink to drain the excess electrons off the electron chain and thus mitigates photoinhibition.
200mmol/LNaCl胁迫对杂交酸模(Rumex K-1)幼苗叶片光系统Ⅱ最大光化学效率(Fv/Frn)没有影响,但是显著降低了光合速率和气孔导度,导致细胞间隙CO_(2)浓度和叶绿素含量增加。同时,盐胁迫引起活性氧清除关键酶超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性上升。在光合作用诱导过程中,无论是对照叶片还是盐胁迫叶片,米勒过氧化反应均维持一部分光合电子流。光合作用达到稳定状态后,盐胁迫叶片仍能够通过米勒过氧化反应维持部分光合电子流。强光下,低氧(2%)抑制米勒过氧化反应对对照叶片光抑制程度没有明显影响,而显著增加盐胁迫叶片的光抑制程度。据上述结果推测:盐胁迫下米勒过氧化反应的增强有助于消耗过剩的激发电子,从而降低强光下杂交酸模幼苗叶片的光抑制程度。
作者
陈华新
安沙舟
李卫军
高辉远
邹琦
CHEN Hua-Xin;AN Sha-Zhou;LI Wei-Jun;GAO Hui-Yuan;ZOU Qi(College of Life Sciences,Shandong Agricultural University.Tai'an 271018,China;Department of Grassland Sciences,Xinjiang Agricultural University,Urumgi 830052,China)
基金
国家重点基础研究发展规划项目(1998010100)
国家自然科学基金(39870604)。
