水稻干旱胁迫诱导DNA甲基化时空变化特征分析

 【目的】研究水稻抗旱导入系DK106和旱敏感轮回亲本IR64苗期和分蘖期干旱胁迫前后DNA甲基化的变化情况，并比较分析叶片和根部DNA甲基化变化特征，探讨DNA甲基化在水稻干旱胁迫反应中的作用。【方法】用甲基化敏感扩增多态性技术（methylation sensitive amplified polymorphism，MSAP）和高效液相层析（high performance liquid chromatography，HPLC）方法分析DNA甲基化变化情况；从聚丙烯酰胺凝胶回收甲基化多态性片段并克隆测序及序列比对。【结果】MSAP分析结果显示，水稻基因组中约有20%的CCGG位点发生了胞嘧啶甲基化；水分胁迫导致DNA甲基化平均水平明显增加，其中根部增加幅度尤为明显；DNA甲基化水平及状态变化在品种间存在差异，同时具有时期及组织特异性。对干旱胁迫特异诱导DNA甲基化片段序列分析结果表明，基因编码区和非编码区发生DNA甲基化的频率基本相同。【结论】干旱胁迫反应过程中DNA甲基化表现出一定时空特异性和品种特异性，且与品种抗旱性差异相关。

Spatial and Temporal Profiling of DNA Methylation Induced by Drought Stress in Rice

【Objective】 This experiment aimed at study of the relationship between DNA methylation and drought responsiveness in rice by characterizing DNA mathylation in leaves and roots at seedling stages and tillering stages under drought stress for DK106 (drought tolerance introgression line) and IR64 (recurrent parent and drought sensitive line). 【Method】 Methylation sensitive amplified polymorphism (MSAP) and high performance liquid chromatography (HPLC) were used to analyze the DNA methylation level in this study; The differentially methylated DNA fragments induced by drought were isolated from the polyacrylamide gel, cloned and sequenced, then the sequences were blasted at the NCBI website. 【Result】 Results showed that about 20% cytosine of CCGG sequences in rice genome was methylated, and the average level of methylation was increased under drought stress treatment, especially in roots; But the alterations of the DNA methylation state and level induced by drought stress were different between DK106 and IR64, and were also specific at different growth stages and in different tissues. The BLAST results of the differentially methylated DNA sequences showed that the methylation frequency was similar in coding region and non-coding region on the genome. 【Conclusion】 It was revealed that the pattern of DNA methylation under drought was temporal-spatial specific and variety specific, and the change of DNA methylation was related to drought responsiveness.