栉孔扇贝、虾夷扇贝及其杂交子代的MSAP分析

Analysis of Chlamys farreri,Patinopecten yessoensis and their offspring using methylation-sensitive amplification polymorphism( MSAP)

运用甲基化敏感扩增多态性(methylation-sensitive amplification polymorphism,MSAP)技术对栉孔扇贝(♀)、虾夷扇贝(♂)及其杂交子一代、子二代基因组DNA胞嘧啶甲基化水平进行了研究,并分析了DNA甲基化与各性状的相关性及其与杂种优势的关系。结果表明,(1)DNA甲基化率与壳宽、总重等表型值呈正相关的关系,而与壳长、壳高、软体重和闭壳肌重4个性状表型值呈负相关的关系,其中闭壳肌重与甲基化率的相关性达到极显著水平(P<0.01);(2)虾夷扇贝、栉孔扇贝、F1代、F2代的总甲基化率分别为32.79%、24.13%、19.98%、20.18%,杂交种F1代的甲基化水平低于双亲,是两种扇贝杂交的结果;F1代的甲基化模式经过了重新调整,其变化相对其亲本主要有4种类型:甲基化水平相同、去甲基化、超甲基化、次甲基化,且去甲基化位点多于超甲基化位点。结果证实杂种优势的产生与杂交种F1代基因组DNA甲基化模式的改变和重新调整有关,丰富了杂种优势机理研究内容。

DNA methylation is related to a number of epigenetic phenomena and plays an important role in gene expression. In this study,the technique of methylation-sensitive amplified polymorphism（ MSAP） was used for the first time to analyze the DNA cytosine methylation of Chlamys farreri,Patinopecten yessoensis, F1 and F2,and we made a concrete analysis between the methylation ratio and phenotypic traits,assessed the extent and pattern of cytosine methylation between the parents and the offspring,and emphasized the discussion on the molecular basis of heterosis in terms of the DNA methylation. The results showed that, （ 1） DNA methylation was negatively related to the shell length,shell height,soft body weight and adductor muscle weight,but positively related to the shell wideness and gross weight,and there was great correlativity between the DNA methylation and the adductor muscle weight（ P 0. 01） ; （ 2） there was a significant difference between the parents and the offspring： the methylation ratio of 5＇-CCGG sites was 32. 79% in P. yessoensis,24. 13% in C. farreri,19. 98% in F1,and 20. 18% in F2 respectively,the methylation ratio of F1 was less than the parents and there was no significant difference between F1 and F2,the alteration of the DNA methylation was the result of the cross of the parents; four classes of MSAP patterns,A,B,C and D, among hybrids and their parents were detected： pattern A,methylation levels were not changed in both parents and F1; pattern B,demethylation,both or one of the parent was methylated,but there was no methylation in the same site in Fl; pattern C,hypermethylation,the methylation level in F1 was higher than those in both parents; pattern D,hypomethylation,methylation ratio in F1 was lower than those in both parents. The patterns of the F1 DNA methylation experienced change and adjustments in order to coordinate the expression of the gene from the parents,and the DNA methylation has something to do with the expression of heterosis.