Heritability and Reversibility of DNA Methylation Induced by in vitro Grafting between Brassica juncea and B. oleracea.
Heritability and Reversibility of DNA Methylation Induced by in vitro Grafting between Brassica juncea and B. oleracea.
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芥菜与甘蓝体外嫁接诱导DNA甲基化的遗传性和可逆性
DOI：
10.1038/srep27233
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发表时间：
2016-06-03
影响因子：
4.6
通讯作者：
Chen L
中科院分区：
文献类型：
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作者：
Cao L;Yu N;Li J;Qi Z;Wang D;Chen L
榨菜与红甘蓝嫁接产生了一个嵌合的TTC茎尖分生组织（SAM），由榨菜的第I层和第II层以及红甘蓝的第III层组成。TTC自交后代GSn（GS =嫁接-自交，n =世代）表现出明显的表型变异，主要表现在叶片形状和SAM上。本文研究了GSn表型变异的遗传力及其与DNA甲基化变化的关系。叶片形状的变化被认为是稳定遗传到GS 5，但SAM变异恢复世代。随后对GS1的DNA甲基化水平进行了测定，结果表明，与榨菜（TTT）相比，GS1的甲基化水平发生了5.29-6.59%的变化，其中31.58%的甲基化水平稳定地传递到GS 5，其余的甲基化水平随着世代的推移逐渐恢复到原来的水平，这表明嫁接诱导的DNA甲基化变化是可遗传的，而且是可逆的。差异甲基化片段（DMFs）的序列分析显示，甲基化主要发生在转座子和外显子区域，这进一步影响了基因的表达，包括开花时间和赤霉素反应相关基因。有趣的是，DMF可以匹配差异表达的siRNA的GS 1，GS 3和GS 5，表明移植诱导的DNA甲基化可以通过siRNA的变化。这些结果表明，嫁接诱导的DNA甲基化可能有助于嫁接诱导的表型变异。
Grafting between tuber mustard and red cabbage produced a chimeric shoot apical meristem (SAM) of TTC, consisting of Layers I and II from Tuber mustard and Layer III from red Cabbage. Phenotypic variations, which mainly showed in leaf shape and SAM, were observed in selfed progenies GSn (GS = grafting-selfing, n = generations) of TTC. Here the heritability of phenotypic variation and its association with DNA methylation changes in GSn were investigated. Variation in leaf shape was found to be stably inherited to GS5, but SAM variation reverted over generations. Subsequent measurement of DNA methylation in GS1 revealed 5.29–6.59% methylation changes compared with tuber mustard (TTT), and 31.58% of these changes were stably transmitted to GS5, but the remainder reverted to the original status over generations, suggesting grafting-induced DNA methylation changes could be both heritable and reversible. Sequence analysis of differentially methylated fragments (DMFs) revealed methylation mainly changed within transposons and exon regions, which further affected the expression of genes, including flowering time- and gibberellin response-related genes. Interestingly, DMFs could match differentially expressed siRNA of GS1, GS3 and GS5, indicating that grafting-induced DNA methylation could be directed by siRNA changes. These results suggest grafting-induced DNA methylation may contribute to phenotypic variations induced by grafting.