Abstract: In order to explore the influences of exogenous ABA on cold resistance of maize,we selected two maize materials(cold resistant Qingnong 105 and the cold sensitive agricultural Nonghua 101 as the experimental materials)were used as the experimental materials,after the treatment of low temperature and external application of ABA. The MDA content,relative conductivity,soluble sugar content,protective enzyme activity and hormone content of two maize varieties were determined,and the expression of low temperature stress related genes was compared by fluorescent quantitative PCR. The results showed that the content of MDA and relative conductivity of two maize varieties under low temperature stress were reduced by exogenous ABA treatment,and the content of soluble sugar was increased. The MDA content and conductivity of the cold resistant cultivar Qingnong 105 decreased greatly,while the soluble sugar content increased greatly,Exogenous ABA played a more significant role in the cold resistance of Qingnong 105. By analysis of enzyme activities and hormone levels,exogenous ABA could improve SOD,POD,CAT,APX activities caused by low temperature stress and enhance the ability of active oxygen in order to reduce the accumulation of reactive oxygen species. Exogenous ABA had more obvious effect on Qingnong 105 than Nonghua 101 because Qingnong 105 possessed stronger increase in SOD,POD,CAT,APX activities. We found that exogenous ABA application increased endogenous ABA biosynthesis under low temperature stress,simultaneously reduced the levels of GA₃,ZR,IAA. The effect of low temperature and ABA treatment on cold-resistant cultivar was more obvious. Molecular evidence from RT-PCR showed that exogenous ABA increased the expression level of some genes involved in abiotic stresses under low temperature stress. By comparison of the capacity of these two varieties to low temperature,low temperature stress leads to upregulated Apx1, Fad8, Lip15, Cat3 gene in these two varieties,also Dreb1, Asr1 gene in Qingnong 105,but downregulated Dreb1, Asr1 gene in Nonghua 101. We found that external application of ABA had a significant effect on cold resistant maize varieties. The data could provide some strategies to avoid damages from chilling injury for maize production in China North Area.

Key words: Maize, ABA, Low temperature, Cold resistance

CLC Number: 

• S513.01