Study Of DNA Methylation Changes Of Salt-tolerant Inbred Lines Under Salt Stress

Maize has the characteristic of poor salt resistance, and the epigenetic plays an important role in many aspects such as growth and development in plant, adversity stress response, gene regulation and so on. The DNA methylation is one of the earliest and most in-depth contents in epigenetics. This article used the MSAP technique to study DNA methylation variations of salt tolerance maize under salt stress which provided preliminary theoretical basis for further research on molecular mechanism of corn salt resistance. The main results were as follows:1、We used bioinformatics prediction to analysis the three copies of corn demethylation enzyme ROS1, coming to the conclusion that the biological characteristics and structure of the protein were highly similar between ROS1-1 and ROS1-2, with ROS1-3 significantly different. The q RT-PCR test indicated hat, the expression of the ROS1-1 and ROS1-2 expressed 2~3 times in the concentration of salt of 200 mmol·L-1 and decreased in that of 250 mmol·L-1. It is consistented with the regulation rule of improving the plant resistance through the mechanism of demethylation under the adversity stress.2、Using 37 pairs of primer to amplify maize genes of six different concentrations, we got about 800 bounds of fagments beween 60~600bp. Under the Na Cl stresss, the genomic DNA methylation ratio is only 50mmol·L-1 Na Cl treatment which was higher than the contrast, when the overall trend is lower. 86.7%~97.6% sites kept the original methylation unchanged, and less sites methylation changed. With the increasing of concentration of salt stress, it changed in the methylation and demethylation at the same time, the methylation mainly changing.3、We successfully recycled and sequenced 28 different stripes from the 35 sites, nine of whicn are functional sites, involving the metabolism of plants, leucine zipper corn protein, serine/threonine protein kinase, cinnamyl alcohol dehydrogenase and related functions. Selecting corn rust resistance gene, corn cinnamyl alcohol dehydrogenase gene to take the q RT-PCR test, the result shows that expression patterns of corn rust resistance gene are consistent with q RT-PCR verification results, which methylated, and the expression decreased; Corn cinnamyl alcohol dehydrogenase gene methylated with lower expression quantity.