The Analysis On Polymorphism Of DNA Methylation In Eupatorium Odoratum

Biological invasion now has become one of the heated issues in the world becauseof the environmental and ecological devastation. Odorata originating in South Americafirst appeared in Yunnan Province since1934. It has been classified as one of the typicalinvasive alien species. Those alien invasions have brought serious harmful effect on theeconomic and ecological environment in China. It is important to explore the invasionmechanism of odorata and other exotic plants in order to prevent biological invasions. Ithas been believed that genome genetic affected biological invasion recently. However,how epigenetic affect biological invasions is also beginning to be a noticeable topic.In this study, we explored the odorata invasion mechanism from epigenetic aspectsby the method of methylation-sensitive amplified polymorphism (MSAP). In the test,we used native species-Mexico ecotype and invasive species-Xishuangbanna ecotype asmaterials, and set three kinds of nitrogen level: low nitrogen (nitrogen content105.055mg/L), normal nitrogen (nitrogen content210.11mg/L) and high nitrogen(nitrogen content315.165mg/L). On the one hand, the test is to explore the correlationof odorata ecotype and DNA methylation Polymorphism; On the other hand, it is toexplore the impact of nitrogen nutrition on DNA methylation odorata. The results of thisstudy has showed as the following:(1) On the site of "CCGG" in Eupatorium odoratum DNA of Mexico type, thelevel of methylation is about21.20%which includes about11.66%of hemi-methylationand9.54%of full methylation. On the site of "CCGG" of Eupatorium odoratum DNAof Xishuangbanna type, the level of methylation is about29.53%which includes about13.23%of hemi-methylation and14.30%of full methylation. Compared with theXishuangbanna type (invaded) and Mexico type (origin), Eupatorium odoratum ofXishuangbanna type has a higher degree of DNA methylation; Just from this point ofview, the odorata of invasion land have resulted in more gene expression beingsuppressed because methylation has increasing constantly.(2) Under the procession of different nitrogen supply levels, the odorata DNAmethylations level is approximately17.87%which is processed by low nitrogen, 25.18%processed by normal nitrogen and33.03%processed by high nitrogen. Differentnitrogen levels affect the extent of DNA methylation, in which DNA methylation levelstend to increase under high nitrogen level decrease under low nitrogen. The supply ofnitrogen is increasing and at the same time methylation levels are also increasing.Therefore, more genes is inhibited by methylation state and can not express. The supplyof nitrogen is reducing, at the same time, the level of methylation is decreasing, too.Therefore, more original gene out of the methylated lifted inhibited state can beexpressed.(3)After the nitrogen supply levels changed, two ecotypes Eupatorium odoratumDNA methylation also changed: the unchanged DNA methylation is about26.89%,including about13.69%high nitrogen and13.20%low nitrogen;there’s about16.54%DNA methylation increasing, including about8.57%high nitrogen and7.97%lownitrogen; there’s about13.81%DNA methylation were changed due to demethylation,including about9.18%high nitrogen and4.36%low nitrogen, and there is also about8.21%DNA methylation unidentified by MSAP method. From the perspective ofchanges in methylation, we can look to the internal variation from simple increase ordecrease. It can be seen that two ecotypes of odorata in high nitrogen methylation levelsare not only an increase in the degree of methylation, but also accompanied by theoccurrence of methylation reduce, maintain, and even variations that MSAP statisticsfailed to text and so on through the changes in methylation patterns. Therefore, whenthe methylation level increases, we can not rule out some of the key sites of methylationlevel decreases, and vice versa.In summary, odorata of origin and invasion environment with different levels ofnitrogen supply will lead to the changes on patterns of DNA methylation. Our results ofthe experiment show that odorata of invasion has a higher degree of DNA methylationthan that of origin. The lower the nitrogen level is, the lower the DNA methylation hasshowed. The next work will focus on screening for methylation gene locus which arechanged and then research and identify how these genes involve in invasion.