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以玉米主栽品种先玉335为试材,研究24-表油菜素内酯(EBR)对低温胁迫下玉米种胚抗氧化能力和低温响应基因表达的影响.结果表明:EBR浸种处理后,玉米种子活力指数和早期幼苗生长显著提高,种胚中超氧自由基(O2-·)含量明显降低,抗氧化酶(包括超氧化物歧化酶SOD、过氧化物酶POD、过氧化氢酶CAT和谷胱甘肽还原酶GR等)活性和非酶类抗氧化物质谷胱甘肽GSH及脯氨酸含量升高,同时促进一氧化氮(NO)的累积,而使用NO清除剂c-PTIO和NO合成酶抑制剂L-NAME处理后,种胚中CAT、POD和脯氨酸含量有所下降,但是外源NO可提高种胚中CAT、POD和脯氨酸的含量,表明EBR诱导的玉米种胚抗氧化能力增加是通过NO介导的.低温胁迫诱导玉米幼胚中P5CS1、CBF1、CBF3和COR15a等基因的表达,EBR处理基因表达进一步提高,而c-PTIO和L-NAME处理基因表达降低;NO供体SNP则提高了这些基因的表达,这表明EBR可能通过NO途径调控低温响应基因的表达.可见,外源EBR可通过NO途径增强玉米种胚抗氧化能力和调控低温响应基因的表达,进而提高低温胁迫的耐受性.
The effects of 24-epibrassinolide (EBR) on the anti-oxidative ability and low-temperature responsive gene expression of maize embryos under low temperature stress were studied using the maize cultivars Xiangyu 335 as test materials.The results showed that after EBR Seed vigor index and early seedling growth were significantly increased, and the content of superoxide radical (O2-) in seed embryos was significantly decreased. The activities of antioxidant enzymes (including superoxide dismutase SOD, peroxidase POD, catalase CAT and Glutathione reductase GR activity) and non-enzymatic antioxidant glutathione GSH and proline content, while promoting the accumulation of nitric oxide (NO), and NO scavenger c-PTIO and NO The contents of CAT, POD and proline in seed embryos decreased after L-NAME treatment, but the content of CAT, POD and proline in embryos was increased by exogenous NO, indicating that EBR-induced maize Increased antioxidant capacity of embryos was mediated by NO.Expression of P5CS1, CBF1, CBF3 and COR15a genes in maize immature embryos was induced by low temperature stress, EBR-treated gene expression was further enhanced, while c-PTIO and L-NAME-treated gene expression was decreased NO donor SNP increased the expression of these genes, suggesting that EBR may pass NO Pathway can regulate the expression of low-temperature response genes.It can be seen that exogenous EBR can enhance the anti-oxidative ability and regulate the gene expression of low-temperature response in maize embryo via NO pathway, and then improve the tolerance of low temperature stress.