盐胁迫下棉花基因组DNA表观遗传变化的MSAP分析

盐胁迫是非生物逆境中对作物危害比较严重的自然灾害之一, 严重影响和制约作物的产量和种植面积。本研究以陆地棉品系YZ1为材料, 调查不同NaCl浓度下棉花幼苗生长及根基因组DNA的甲基化水平和变化模式。结果表明，对棉花幼苗的株高和根长生长100 mmol L^-1 NaCl有促进作用, 200 mmol L^-1 NaCl有显著抑制作用；100~200 mmol L^-1 NaCl胁迫严重抑制棉花幼苗的侧根数量。甲基化敏感扩增多态性(methylation-sensitive amplification polymorphism, MSAP)分析表明, 经100、150和200 mmol L^-1 NaCl处理后根基因组DNA甲基化比率分别为38.1%、35.2和34.5%, 均低于对照(41.2%), 同时棉花幼苗根DNA的甲基化水平与NaCl处理浓度呈显著负相关(r = –0.986)。与对照相比, 100、150和200 mmol L^-1 NaCl胁迫下棉花幼苗根基因组DNA的甲基化和去甲基化分别为6.4%、7.6%、11.3%和12.7%、11.1%、8.2%。此外, 序列和RT-PCR分析表明, 与MSAP差异片段高度同源的基因的表达在处理与对照间差异显著。

MSAP Analysis of Epigenetic Changes in Cotton (Gossypium hirsutum L.) under Salt Stress

Salinity is one of the important limiting factors in plant production worldwide. The objectives of the study were to assess the effect of salt stress on the plant growth and to determine if DNA can be methylated in cotton plants (Gossypium hirsutum) by methylation-sensitive amplified polymorphism (MSAP) technique. The results showed that 100 mmol L^-1 NaCl obviously promoted plant height and root length of cotton seedlings, but 200 mmol L^-1 NaCl significantly inhibited plant growth; 100–200 mmol L^-1 NaCl inhibited the number of lateral root considerably. The analysis of MSAP showed that the level of global DNA methylation decreased from 41.2% to 34.5% as the salt concentrations increased; there was a significantly negative correlation (r = –0.986) between NaCl concentrations and the level of DNA methylation in cotton roots. Under stresses of 100, 150 and 200 mmol L^-1 NaCl, methylation and demethylation of DNA were 6.4%, 7.6%, 11.3% and 12.7%, 11.1%, 8.2%, respectively. In addition, the analyses of sequences and RT-PCR showed that expressions of genes homologous to MSAP fragments in roots were different between control and treated plants under salt stress, suggesting that these genes would play an important role in the cotton adaptation of salt stress.