不同溶质型桃果实成熟衰老过程中线粒体内细胞色素氧化酶的变化

Changes in Mitochondrial Cytochrome c Oxidase in Two Peach Cultivars during Maturation and Senescence

以软溶质型桃‘雨花3号’和硬溶质型桃‘加纳岩’果实为试材,研究不同溶质型桃成熟衰老过程中细胞色素氧化酶(cytochrome c oxidase,COX)活性以及线粒体编码的COX 3种亚基(COXⅠ、COXⅡ、COXⅢ)基因表达量的变化。结果表明:桃果实成熟前期,COX活性不断增加,成熟后期,COX活性开始下降。‘加纳岩’COX 3种亚基基因的表达量高于‘雨花3号’,且COX 3种亚基在桃果实成熟前期表达量较高。说明线粒体DNA编码的COX 3种亚基主要作用于桃果实成熟前期,为果实生长代谢提供所需能量,到了后期表达量降低,活性受影响,导致果实线粒体内的活性氧积累,机体代谢失衡,呼吸速率增加,线粒体编码的COX 3种亚基与桃果实成熟衰老之间存在一定的内在联系。

The activity of cytochrome c oxidase(COX) and the expression levels of mitochondrial DNA(mtDNA)-encoded COX subunits in two peach(Prumus persica) cultivars ‘Yuhuasanhao' and ‘Jianayan' were determined for analyzing their relationship with peach fruit ripening and senescence. The results showed that COX activities in the two peach cultivars increased in the early stages of maturity(Ⅰ–Ⅲ), followed by a decrease. COX activities were higher in ‘Jianayan' peach fruit than in ‘Yuhua 3' peach fruit. The expression levels of mtDNA- encoded COX subunits were higher in the early stage than in the later stage of maturity. MtDNA-encoded COX subunits played a major role in the early maturity stage of peach fruit and provided the energy needed for peach growth and metabolism. In the later maturity stage, the decreases in the abundance of catalytic subunits of mtDNA-encoded COX could underlie the senescence-associated loss of enzyme activity, which could change a component of the mitochondrial electron transport chain and underlie the senescence-related decrease in mitochondrial respiratory activity and reactive oxygen species accumulation.