MSAP analysis of DNA methylation of Ziziphus jujuba 'Dongzao' by rainproof cultivation

During the growth of plants, genomic DNA methylation will also change with the influence of external factors, thus participating in many important life processes of plants. In this study, five developmental stages of 'Dongzao' (Ziziphus jujuba Mill.) fruits under two treatments of rainproof (RP) cultivation and open-field (OF) cultivation were used as materials, MSAP technology was used to study the changes in methylation level patterns during the development of jujube fruits, and to explore the involvement of DNA methylation in fruit development of 'Dongzao' and response to RP reaction mechanism. The results showed that the total methylation level of genomic DNA decreased as the fruit matured in both RP and OF cultivation. The total methylation level of OF-cultivated fruit was lower than that in RP-cultivated fruit during the same period. The rate of full methylation showed a similar trend. There were both methylation and demethylation changes in every two adjacent stages of fruit in RP and OF cultivation. As the fruit develops, the ratio of demethylation was higher than the ratio of methylation. Under the two treatments, the comparison result in the same period was mainly the occurrence of hypermethylation. As the fruit matures, the proportion of methylation and demethylation induced by RP cultivation in cytosine increased. Serine/threonine-protein kinase, hypothetical protein, DEAD helicases superfamily protein, WD40 protein, lipoate synthase, RNA polymerase factor and other related genes were isolated. The methylation of these genes occurred during fruit development and in response to RP environment. The genome of 'Dongzao' has abundant methylation modifications at different stages of fruit development, and it is possible to adjust the expression of these functional genes to respond to fruit development and RP environment. Those results provide theoretical basis for the research on the adaptive mechanism and epigenetic expression regulation of jujube fruit development.