野生稻Oryza nivara和O.rufipogon DNA甲基化多样性

Surveying DNA methylation diversity in the wild rice, Oryza nivara and O. rufipogon

本文调查研究了野生稻群体内及群体间的DNA甲基化多样性。选取与亚洲栽培稻近缘的两个野生种Oryza nivara和O.rufipogon作为研究对象,采用改进的MSAP(methylation-sensitive amplification polymorphism)技术对其基因组CCGG位点的甲基化多样性进行了分析。结果表明:在同一个IRGC(the International Rice Germplasm Center)编号群体内的不同个体间,基因组甲基化条带高度一致;而在不同编号群体间,甲基化条带表现为多态。其中后者又可以分为两类:条带模式高度一致的Class I和条带模式呈多态性的Class II。将上述两类甲基化片段的编码基因与栽培稻粳稻(O.sativa L.subsp.japonica)和籼稻(O.sativa L.subsp.indica)两个亚种的同源基因进行序列比对发现,在进化趋势上Class I表现得比较保守,而Class II较为活跃。DNA甲基化多样性作为标志遗传多样性的一种信息来源,其在群体分化及物种进化过程中的作用还需要进一步探讨。

Intra-and inter-population methylation diversity at CCGG sites were surveyed in the genomes of Oryza nivara and O. rufipogon using a modified MSAP （methylation-sensitive amplification polymorphism） technique. These two wild species were closely related to cultivated rice in that they share the common A genome. Results revealed that methylated bands were uniform among different individuals of the same IRGC （International Rice Germplasm Center） accession, but polymorphic among different populations within the IRGC. Methylated bands could be divided into two categories, i.e., the conserved group （Class I）, and the polymorphic group （Class II）. Comparing the gene sequences of the two classes to the homologous sequences of japonica and indica varieties, Class I was conservative, but Class II was variable and evolutionarily active. DNA methylation diversity was an informative indicator of genetic diversity in Oryza. However, further studies of population differentiation and species evolution are needed.