除草剂对不同耐寒性水稻幼苗的氧化胁迫效应

HERBICIDE-INDUCED OXIDATIVE STRESS IN SEEDLINGS OF TWO RICE CULTIVARS WITH DIFFERENT CHILLING TOLERANCE

通过分析比较百草枯和丙酯草醚处理以及零上低温处理对水稻幼苗的生长、膜脂过氧化及抗氧化剂水平的效应,研究了新型除草剂丙酯草醚对不同耐寒性水稻品种(耐寒性品种圣稻13和冷敏感性品种IR50)的氧化胁迫特征。结果显示,100 nmol/L丙酯草醚处理显著抑制圣稻13和IR50幼苗的生长,但50 nmol/L百草枯仅对IR50幼苗生长有显著抑制。百草枯处理使2个水稻品种的丙二醛(MDA)有大幅度提升,这与百草枯通过产生氧自由基的杀草机理相符,而圣稻13对百草枯一定程度的抗性可能与其谷胱甘肽和抗坏血酸的上升响应有关。丙酯草醚处理虽然引起圣稻13中MDA的上升,但对IR50的MDA含量没有显著影响,表明丙酯草醚处理对圣稻13造成了氧化胁迫伤害,而对IR50的生长抑制可能与氧化胁迫没有密切关系。H2O2处理后,圣稻13中H2O2含量略有下降,而IR50中H2O2含量却有较大幅度的上升,这提示,冷敏感性品种IR50可能通过H2O2预处理来增加其抗性。

Seedling growth of two rice （ Oryza sativa L. ） cultivars, ShengDao 13 （SD13, chilling-tolerant） and IR50 （chilling susceptible） was significantly inhibited by pyribambenz-propyl （at 100 nmol/L）, whereas only that of IR50 was inhibited by paraquat （at 50 nmol/L）. MDA contents in leaves of both cuhivars were signific,antly elevated by paraquat treatment, in line with the latter＇s herbicidal mechanism of generating ROS in green tissues under light. On the other hand, MDA content of SD13 but not of IR50 was increased by pyribambenz-propyl, implicating that the herbicide caused in SD13 oxidative stress, which, was not apparent in IR50. The limited tolerance of SD13 to paraquat could be related to the rise of GSH and AsA in response to the herbicide. After growing in lmmol/L H2O2 for five days, H2O2 content in SD13 decreased slightly while that in IR50 rose significantly, suggesting the likelihood of improving stress-tolerance of the chilling-susceptible rice cuhivar by pretreatment with H2O2.