SA对低温胁迫后枇杷幼果AsA-GSH循环酶系统的影响

摘要

A study on effects of salicylic acid ( SA ) treatment on enzymes of ascorbate-glutathione cycle in young loquat ( Eriobotrya japonica cv. ' Zaozhong No. 6' ) fruits was conducted to explore the mechanism of SA in promoting the chill-resistance of young loquat fruits to low temperature. Results indicated that 40 and 70 mg'L1 SA treatments increased the reduced glutathione ( GSH) contents, and decreased the oxidized glutathione ( GSSG) content. Therefore, the treatment resulted in elevating the ratio of GSH/GSSG in young loquat fruits under low temperature stress. Meanwhile, SA treatment also promoted the activities of GSH-dependent glutathione reductase ( GR) , glutathione-S-transferases ( GST) , and glutathione peroxidase ( GPX) in young loquat fruits, which could activate its cell detoxification function by degrading peroxides caused by low temperature stress. Furthermore, SA treatment increased ascorbate peroxidase ( APX ) , dehydroascorbate reductase(DHAR) , monodehydroascorbate reductase (MDAR) activities and ascorbate (AsA) contents, and decreased the contents of dehydroascorbate (DHA) , super hydrogen (H2O2) , malondialdehyde (MDA) contents and relative electric conductivity (REC) , which led to an increase of AsA/DHA ratio, and ultimately resulted in alleviating the oxidative damage caused by low temperature stress. It is concluded that SA could significantly improve oxidation resistance and chill-resistance of young loquat fruits. SA concentration at 70 mg-L" was preferable for young loquat fruits.%研究水杨酸处理对"早钟6号"枇杷幼果AsA-GSH循环酶系统的影响,探讨SA对枇杷幼果抗寒性的作用机理.结果表明:采用40和70 mg·L-1的SA处理可提高低温胁迫后枇杷幼果还原型谷胱甘肽(GSH)含量,降低氧化型谷胱甘肽(GSSG)含量,导致GSH/GSSG比率的上升,同时也提高低温胁迫后枇杷幼果谷胱甘肽还原酶(GR)、谷胱甘肽过氧化物酶(GPX)和谷胱甘肽-S-转移酶(GST)的活性,启动细胞的解毒功能,从而降解低温胁迫后所产生的过量过氧化产物.此外,SA处理还可提高低温胁迫后枇杷幼果抗坏血酸过氧化物酶(APX)、脱氢抗坏血酸还原酶(DHAR)和单脱氢抗坏血酸还原酶(MDAR)活性以及还原型抗坏血酸(AsA)含量,降低氧化型抗坏血酸(DHA)、过氧化氢(H2O2)和丙二醛(MDA)含量以及相对电导率(REC),导致AsA/DHA比率的上升,提高枇杷幼果组织内部的抗氧化能力,从而起到保护作用.SA处理可提高低温胁迫后枇杷幼果的抗氧化性,增强其抗寒能力,其中以70 mg·L-1的SA处理效果较好.