DNA methylation has been proposed to regulate plant stress resistance. However, the dynamic changes in DNA methylation in woody plants and their correlations with pathogenic responses are not fully understood. Here, we present single-base maps of the DNA methylomes of mulberry (Morus notabilis) leaves that were subjected to a mock treatment or inoculation with Botrytis cinerea. Compared with the former, the latter showed decreased mCG and mCHG levels and increased mCHH levels. DNA methylation inhibitors reduced resistance gene methylation levels and enhanced mulberry resistance, suggesting that the hypomethylation of resistance genes affects mulberry resistance to B. cinerea. Virus-induced gene silencing of MnMET1 enhanced the expression of mulberry-resistance genes, thereby increasing the plant’s resistance to B. cinerea. We also found that MITEs play a dominant role in controlling DNA methylation levels. MITEs appear to be the main sources of 24-nt siRNAs that regulate gene expression through the RNA-directed DNA methylation pathway.

中文翻译：

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桑树 (Morus notabilis) 对灰霉病的反应中转座因子和基因甲基化的动态变化

已经提出DNA甲基化来调节植物的抗逆性。然而，木本植物中 DNA 甲基化的动态变化及其与病原反应的相关性尚不完全清楚。在这里，我们展示了桑树 DNA 甲基化组的单碱基图谱（桑葚) 进行模拟处理或接种的叶子灰霉病菌. 与前者相比，后者表现为mCG和mCHG水平降低，mCHH水平升高。DNA甲基化抑制剂降低了抗性基因甲基化水平并增强了桑树的抗性，表明抗性基因的低甲基化影响了桑树的抗性。B. cinerea. 病毒诱导的基因沉默锰MET1增强桑树抗性基因的表达，从而提高植物对桑树的抗性B. cinerea. 我们还发现螨虫s 在控制 DNA 甲基化水平中起主要作用。螨虫s 似乎是 24-nt siRNA 的主要来源，它们通过 RNA 指导的 DNA 甲基化途径调节基因表达。