外源一氧化氮对铝胁迫下烟草叶片呼吸作用和活性氧代谢的影响

为探明外源一氧化氮(NO)提高烟草耐铝性的生理机制,采用水培法研究了NO供体硝普钠(SNP)对铝胁迫下2个不同耐铝性烟草品种云烟100(耐铝)和云烟105(敏感)植株生长、叶片活性氧(ROS)含量、呼吸作用和线粒体抗氧化酶活性的影响。结果表明,铝胁迫显著降低了烟草叶片总呼吸速率、细胞色素呼吸速率、交替呼吸速率、细胞色素氧化酶(COX)活性和丙酮酸含量,导致叶片O—·2产生速率升高和H2O2大量积累,植株生物量显著下降,且云烟105变幅高于云烟100;外源NO处理显著缓解铝对烟草植株生长的抑制,提高叶片总呼吸速率、细胞色素呼吸速率、交替呼吸速率、COX活性和丙酮酸含量,降低叶片O—·2产生速率和H2O2含量,且对云烟105的缓解效果显著高于云烟100。此外,外源NO处理进一步提高铝胁迫下烟草叶片线粒体超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性,且云烟105增幅显著大于云烟100。综上所述,外源NO处理可通过提高烟草叶片呼吸作用和线粒体抗氧化酶活性来清除线粒体内ROS含量,从而缓解铝对烟草的毒害作用,且对敏感基因型的缓解效应较耐铝基因型更为明显。

Effects of Application of Nitric Oxide on Respiration and Reactive Oxygen Metabolism in Leaves of Tobacoo under Aluminum Stress

Two different aluminum (Al)-tolerant tobacoo cultivars Yunyan 100 (Al-tolerant) and Yunyan 105 (Al-sensitive) were used to study the effects of sodium nitroprusside(SNP,an exogenous NO donor) on plant growth,leaf reactive oxygen content and respiration,activities of antioxidant enzymes in mitochondria under Al stress using solution culture method,so as to find out exogenous NO-increased Al resistant mechanisms in tobacoo.The results showed that Al dramatically decreased leaf total respiration rate,cytochrome respiration rate,alternative respiration rate,cytochrome oxidase (COX) activity and pyruvate content,leading to the increase of leaf O2-· producing rate and H2O2 accumulation,and decrease of plant biomass,the variable amplitude in Yunyan 105 was bigger than that in Yunyan 100.Under Al stress,application of exogenous NO alleviated Al-induced inhibition of plant biomass,increased leaf total respiration rate,cytochrome respiration rate,alternative respiration rate,COX activity and pyruvate content,decreased leaf O2-· producing rate and H2O2 content,the alleviating effect was more significantly in Yunyan 105 than that in Yunyan 100.Furthermore,application of exogenous NO also increased activities of superoxide dismutase(SOD) and ascobate peroxidase(APX) in mitochondria,the increase amplitude was more significantly in Yunyan 105 than that in Yunyan 100 under Al stress.Therefore,the application of exogenous NO could alleviate Al phytotoxicity in tobacoo mainly by enhancing leaf respiration and activities of SOD and APX in mitochondria,which eliminated ROS in mitochondria,and the alleviating effect was greater in the Al-sensitive genotype than that in the Al-tolerant genotype.