杉木亲本自交系及其杂交种DNA甲基化和表观遗传变异

Epigenetic Inheritance and Variation of DNA Methylation in Chinese Fir (Cunninghamia lanceolata) Intraspecific Hybrids

表观遗传调控包括DNA甲基化、染色质结构修饰和小分子RNA调控等机制可能在杂种优势形成过程中起重要作用。为了了解DNA甲基化对杉木杂交后代杂种优势的影响,本研究利用甲基化敏感随机扩增PCR技术(methylation-sensitive AP-PCR,MS-AP-PCR),选取40对引物组合对杉木亲本自交及其亲本的杂交组合后代群体的基因组DNA进行了扩增和分析。结果表明:杉木基因组的DNA甲基化模式主要以内侧胞嘧啶的甲基化为主;6个正反交组合总的甲基化百分率相对于亲本的自交系而言,甲基化率呈减少的趋势;同一组合正反交组合后代之间在CCGG位点胞嘧啶的甲基化水平上无明显差异;6个杂交组合在CCGG的位点上的甲基化位点数明显低于它们的亲本自交子代。对3种甲基化的表达类型与性状表型值、杂种优势值、配合力进行的相关分析结果表明,检测位点外侧胞嘧啶半甲基化、内侧胞嘧啶甲基化位点变化与杉木树高,胸径和材积性状的杂种优势均成显著负相关,即杉木基因组外侧胞嘧啶半甲基化程度越低、内侧胞嘧啶甲基化位点越少,3个生长性状的杂种优势愈明显;而其他甲基化程度的指标与杂种优势之间的相关均没有达到统计学的显著水平。

Epigenetic phenomena were to be recognized as the interference or regulation by DNA methylatlon, chromatin structure modification, or microRNA regulation. Meanwhile, these regulators were to be thought playing an important role on the expression ofheterosis in F1 hybrid. We analyzed the effect ofDNA methylation on heterosis by the means of methylation-sensitive AP-PCR technique with 40 primer combinations based on the genome DNA of Chinese fir hybrids and their parents＇ selfing. The results were shown that the inner-methylation of double-stranded DNA was the main pattern of the genomic DNA methylation on Chinese fir. The relative lower values of cytosine methylation at CCGG sites among hybrids were observed, comparing with their corresponding selfing; no difference was observed between reciprocal crosses for a given parents combination. The methylation percentage at CCGG sites among the six crosses was significantly lower than their parents＇ selfing. There were significantly negative correlation both between the inner methylation of double-stranded DNA, outer methylation of single-stranded DNA patterns and the heterosis, in other words, the hybrids with lower level of outer hemi-methylation sites of cosine, and less inner fully methylation sites of cosine on genomic DNA of Chinese fir, may have more significant heterosis.