小麦抗条锈病过敏性坏死反应中的活性氧代谢

Metabolism of reactive oxygen species in the process of hypersensitive response of wheat to stripe rust

【目的】探讨活性氧在植物抗病菌侵染反应中的作用。【方法】以小麦洛夫林13为供试植物,条锈病菌单孢菌系CY23-2、CY25-8和CY29-3为供试病菌,从小麦与条锈病菌之间典型的过敏性坏死反应(HR)中,探讨活性氧的积累、保护酶系活性变化和原生质膜的透性改变与过敏性坏死反应(HR)的关系。【结果】不亲和条锈病菌CY23-2和CY25-8侵染可引起小麦叶片内2个活性氧的积累高峰,分别出现在接种后第2天和接种后第5～6天。亲和条锈病菌CY29-3的侵染只引起1个活性氧积累高峰,出现时间与不亲和互作的第2个活性氧高峰期一致。不亲和互作中,小麦叶片上产生过敏性坏死反应只出现在第1次活性氧突增之后,表明第1次活性氧突增与HR的产生有关;伴随着小麦叶片中强度极高活性氧的突增,叶片细胞原生质膜遭到破坏,细胞内物质外渗,细胞不久死亡。表明高强度活性氧突增会导致细胞的死亡;对2种互作体系中可清除活性氧的酶系(超氧化物歧化酶、过氧化氢酶、过氧化物酶)活性分析可知,接种后第2天活性氧突增的主要成分是H2O2,接种后第6天活性氧突增的主要成分是O2.-。【结论】H2O2是HR发生的主要信号物,超氧阴离子O2-.等在细胞死亡中起着关键的作用。

[Objective] This study was to understand what roles reactive oxygen species （ROS） played in the defence responses for plants to cope with pathogenic infections. [Method] With wheat variety Lovrinl3 and three different clones of wheat stripe rust strains, namely CY23-2, CY25-8 and CY29-3, as test strains,changes of ROS, activities of superoxide dismutase （SOD）, peroxidase （POD） and catalase （CAT） ,enzymes that are known to detoxify ROS in plant,and permeability of cell plasma membrane were investigated in the process of hypersensitive response of wheat to stripe rust. [Result] The time course of ROS detected by ESR showed that avirulent or incompatible rust strains （CY23-2 and CY25-8） could cause two peaks of ROS production in wheat leaves inoculated with the strains. The first peak occurred on the second day after inoculation whereas the second peak happened on the sixth day after inoculation. However,only one single peak of ROS production was observed on the sixth day after inoculation with virulent or compatible strain,CY29-3. HR, occurred in the incompatible interaction system, associated only with the early oxidative burst of ROS. This implicated that early oxidative burst could mediate the occurrence of HR. Accompanied with a big amount of ROS produced in the infected wheat leaves,cell plasma membrane could be damaged,substances in cell leaked out and cell died soon. This indicated that strong ROS could cause ceil death. The activities of the three enzymes implied that H2O2 ought to be the major component of ROS two days after inoculation,and O2^-↑· could be the major component of ROS six days after inoculation. [Conclusion] Our study results suggested that H2O2 was the signaling substance in HR of wheat to incompatible rust strains and O2^-↑· played a major role in the process of plant cell death.