转基因白桦不同月份叶片基因组DNA甲基化水平的变异  

Genomic DNA Methylation Level Variation of Transgenic Birch Leaves in Different Months

作　　者：刘堃[1] 曾凡锁[1] 李博[1] 詹亚光[1] 

机构地区：[1]东北林业大学生命科学学院,黑龙江哈尔滨150040

出　　处：《生物技术通讯》2013年第1期65-70,共6页Letters in Biotechnology

基　　金：国家自然科学基金(30872045;31200463);黑龙江省自然科学基金重点项目(ZD200918);黑龙江省高校青年学术骨干计划(1155G08)

摘　　要：目的：以转坛￡抗虫基因白桦的不同月份叶片为实验材料，揭示基因组DNA甲基化水平与植物叶片发育及外源基因表达水平之间的相关性。方法：应用DNA-MSAP方法检测叶片基因组DNACCGG位点甲基化状态，利用Northern杂交技术分析其外源基因表达水平。结果：转基因白桦叶片基因组DNA同年5～9月总甲基化水平分别为21．95％、29．62％、25．41％、41.39％和47．24％，除7月份稍有波动外，整体呈现随着叶片的成熟和衰老渐升高趋势；全部扩增位点中，半、全甲基化位点比例分别为17．99％和15．19％，在各月份叶片中变化较大，其中半甲基化位点比例分别为10．37％、19．14％、14．92％、17．2％和28．83％，全甲基化位点比例依次为11．58％、10．49％、10．50％、24．11％和18．40％。同一无性系外源基因在当年5～7月表达量最高，8～9月呈下降趋势，与基因组甲基化状态呈负相关趋势。结论：转基因白桦叶片的成熟和衰老及外源基因表达量降低均可能与基因组DNA甲基化水平的升高相关。Objective： To reveal the correlation between the level of genomic DNA methylation and the develop- ment of plant leaves and the expression of foreign gene, leaves of different months from birch（Betula platyphylla Suk.） plants transferred bgt insect-resistant genes were selected as the experimental materials in this paper. Meth- ods： A suitable DNA-MSAP reaction system was used to detect and analyze the level of DNA methylation. Mean- while, the transcription level of foreign gene was analyzed by Northern blotting. Results： The total genomic DNA methylation rates of May to September were 21.95%, 29.62%, 25.41%, 41.39% and 47.24%, respectively, showing a gradually increasing trend with the ripening and senescence apart from a slight fluctuation in July. The probabili- ty of half methylation sites and fully-methylation sites were 17.99% and 15.19% in total sites, and it was signifi- cantly different among the five chosen time points. The proportion of half methylation sites in May to September were 10.37%, 19.14%, 14.92%, 17.2% and 28.83%, respectively, while that of fully methylation were 11.58%, 10.49%, 10.50%, 24.11% and 18.40%. Meanwhile, the expression levels of foreign gene from the same clone were much higher in May to July while a downward trend was presented in August and September, showing a negative correlation with the methylation status of genomic DNA. Conclusion： All the results above indicated that both ma- turity and senescence of transgenic birch and the decreasing transcriptional expression of foreign genes may be re- lated to the increasing DNA methvlation level.

关 键 词：转基因白桦 基因组 甲基化 甲基化敏感扩增多态性 

分 类 号：Q945[生物学—植物学]