The Study Of DNA Methylation Patterns And Activities Of Antioxidant Enzymes Arising From Lead Stress In Maize Inbred Lines

Heavy metal pollution has become one of the biggest environmental problems in the largest area. And lead as the second heavy metal, which caused tremendous influence for growth and yield of crop sand then threatened our health and food safety. In this study, MSAP technology was adopted to test overall DNA methylation level of the genome in 178, Zheng58, S37 and 9782 in different period under different lead concentration stress. And the main methylation variation sites and methylation mutation modes of these materials were analysised. And the enzyme activity of SOD, POD and CAT were also determinated. The main research results are as follows:1. We measured overall methylation level of 18.36-32.37% and 21.31 27.53% in different varieties of materials under lead stress. And, the contrast detected an average total methylation level for 22.7% in each experiment which was consistent with other researchers'results of the study in maize.2. Methylation sites can almost maintain its methylation state and the largest methylation variations occur for only 25.67%, However hemimethylation levels performanced the significant change, such as in dispose 3 after 48 hours'stress, decreased 46% than the constrast.3. We found there is a certain relationship between maintaining at a higher methylation level and strengthening the plant resistance after stress,. The level of higher resistance materials 178 methylation is significantly higher than S37 and Zheng58, which demonstrated that high resistance material has tended to methylation, while lower resistance material tended to demethylation. It may be that the different resistance materials have made different approach to resist stress.4. Various data is consistent between the result of the MSAP analysis in 9782 roots and leaves, It is suggested that different organizations of the same material in response to stress the same responses in basically. However, demethylation function embodied more apparent in root. Thus, we demonstrated that heritance traits determinded the responsive mode in different tissues and organs which responsed to lead stress. 5. The specific segments were recycled sequenced, and compared through Maize genomes libraries. And the homology fragments were predicted, which confirmed that most of them involved in cell antioxidant pathways and signal transduction pathways, and some transcription factors involved in protein synthesis and hormone synthesis. It was also predicted that the function of DNA methylation in plants was most complex, and most important in plant responsed to stress through many ways.6. SOD,POD and CAT appeared dramatically change in various materials after Stress, POD and CAT is consistent with the changing trend, increasing first and then decreasing, SOD performance first dropped substantially, and then slightly decreased. It is predicted that these enzymes were very sensitive to changes and scavenge free radicals to response to stress in the environment and these results have important significance in our future resistance research. Such as the activity level are obviously difference in different material sand the overall performance of 9782 is the best, Zheng58 is medial, and S37 is the worst.