中文摘要：

研究了50μmol／L除草剂norflurazon（NF）对自然干旱胁迫下拟南芥野生型植株和叶绿体信号突变体gunl和gun5的生理参数和一些抗性基因转录水平的影响．干旱胁迫与除草剂协同处理10d时，叶片出现白化和萎蔫；叶片含水量明显下降；丙二醛含量大幅度升高；活性氧积累明显加重；Lhcb基因表达下调；POD，APX，GPX和Rd29a基因的转录水平显著上调．突变体gunl和gun5叶片白化比野生型严重；突变体生理指标的变化幅度比野生型大；突变体基因表达的变化幅度很小（甚至没有变化），远小于野生型．这些结果表明，叶绿体信号的关键分子GUNl和GUN5蛋白可能参与了干旱信号传导和适应机制，尤其是GUN1蛋白的作用更为明显，暗示叶绿体信号转导途径可能与植物抗逆过程有交叉．

英文摘要：

The effect of 50 9mol/L norflurazon （NF） on the physiological parameters and the transcrip- tional levels of resistance genes of Arabidopsis wild-type seedlings and two plastid-signaling mutants （gun1 and gun5） under drought stress were studied. 10 days after the drought and NF co-stress, the leaves were wilting and photo-bleached; leaf absolute water content decreased; malondialdehyde （MDA） content significantly increased; reactive oxygen species （ROS） accumulation was induced; Lhcb gene expression was down-regulated and POD, APX, GPX and Rd29a gene expression was apparently up-regulated. However, the mutant leaves were more severely photo-bleached and the changes of physiological parameters and gene expression were less （sometimes unchanged） in gun1 or gun5 mutants than in the wild-type plants. The results indicate that GUN1 and GUN5 proteins, two key factors mediating plastid signaling, may participate in plant adaptation to water stress and drought signaling, especially for the GUN1 protein. There might be a crosstalk between plastid signaling and abiotic stress tolerance.