The Cold Response Of Some Antioxidant Relative Traits And Differential Expression Analysis Of GST Genes In Cold Winter Wheat At Low Temperature

Temperature is one of the main factors limiting crop cultivation, which determines thegeographical distribution of plant growth. Heilongjiang province belongs to alpine region, the minimum temperature can reach-40 ℃in winter.Because the different varieties of cold tolerance in winter wheat, winter wheat cannot safe generally wintering in Heilongjiang, N ortheast Agricultural University from which bred wheat DM1 in some areas of Heilongjian g Province can live through winter safty. But the molecular mechanisms of coldhardiness were not yet fully revealed. Our previous studies had shown that cell damage of different cold hardiness cultivars was different significantly in winter wheat at low temperature. Thechanges in active oxygen content to maintain the stability of the cell membrane has an i mportant role at low temperature. At the same time, to cold resistance different winter wh eat transcriptome sequencing results showed that active oxygen scavenging enzyme genes’ e xpressions were significantly different among winter wheat cultivars at low temperature. Bu t the impact had not been systematically studied, which of content of active oxygen scave nging and the expressions of associated genes at low temperature in different cold toleranc e winter wheat varieties. So the above questionsins were analyzed in this study, in ordre t o reveal the reasons of enzyme stability at low temperature in winter wheat, but also laid the foundation for cold hardiness winter wheat genetic improvement. Two varieties(DNDM1 and JM22) with different cold resistance were used for experiment and sampled at cold-acclimation period(October 10 to November 16) and frozen period(On November 16 to t he next year on January 30). The contents of antioxidants(GSH, ASA) and the activities of antioxidant enzymes(SOD, POD) were examined. From Our team previous digital expre ssion profiling of transcriptome level screened out eight glutathione S-transferase genes. Inorder to determine the different expression of enzyme glutathione S-transferase genes in w inter wheat unter freezing stress, set the eight sampling periods by low-temperature incubat or indoor simulation method. And the sampling periods respectively were that without the cold acclimation(CK)、4℃6h、4℃30d,-10℃2h、-12℃2h、-14℃2h、-16℃2h and-18℃2h.Finally by combining the result of the physiological and biochemical indexes and quantita tive analysis provide theoretical basis for cold winter wheat breeding.The results were as f ollows:(1)The membrane damage had significant differences among winter wheat varieties after frozen 30 d.The relative conductivity and MDA content of DM1 below to JM22 under the same conditions. The content changes of SOD and ASA were consistent with the relative conductivity. The SOD activity increased after frozen 15 d, and the ASA content in cold resistance variety was higher than in cold-sensitive variety after frozen 30 d. The increase of SOD and POD activitis had benefit to relieve the membrane damage in winter wheat at low tempreature treatment. The SOD was more direct than POD as the identification index of cold hardiness. But just using antioxidant enzyme up to judge plant cold resistance strength was not sufficient. And the ASA was more direct than GSH in ative oxygen scavenging.(2)The result of RT-PCR shows that there were obvious expression differences in the 8 GST genes among different cold resistance varieties at low temperature and freezing treatment. But the different expressions appeared in different treatments. The peak expression of GSTU3、GST19E50 and GSTU1 C occurred after cold acclimation(4℃,6h), and the maximum up-regulated expression of GSTU1 A and GSTU3 genes appeared in deep freeze treatment. The remaining three genes(GST2, GST24 and GSTU1B) were down-regulated expression in DM1 relative to JM22.(3)The change of glutathione(GSH) content in the same trend between two varieties at low temperature environment indoor. The contents of GSH in DM1 were always significantly higher than in JM22 after each sampling period. The maximum of GSH content in DM1 was 5.53μg/(g·Fw), and which occurred after cold acclimation 6h, cold acclimation 30 d and-10 ℃2h(C treatment). The peak of GSH content was 3.79μg/(g·Fw) in JM22.