中文摘要：

十字花科黑腐病菌，学名野油菜黄单胞菌野油菜致病变种（Xanthomonas campestris pv.campestris，简称Xcc），是一类γ-变形菌纲的革兰氏阴性细菌，能在世界范围内侵染十字花科植物，给农业生产造成重大损失。RNA是分子生物学的主要研究对象之一，提取高质量的RNA是研究十字花科黑腐病菌基因表达调控机理的基础。由于Xcc能产生大量胞外多糖及黄单胞色素，且细菌RNA半衰期较短，目前尚缺少一种大量提取Xcc高质量RNA的有效方法。该研究在参考多种RNA提取方法的基础上，建立了一种简单、有效的适合十字花科黑腐病菌RNA的提取方法。得到的RNA样品经过紫外分光光度法和甲醛变性凝胶电泳检测，证实为完整、均一的总RNA，达到了表达谱分析及cDNA文库构建的要求。

英文摘要：

Xanthomonas campestris pathovar campestris （Xcc） is a yellow pigmented gramnegative bacterium that belongs to the γ-subdivision of proteobacteria. This bacterium can infect cruciferous plants world-wide, causing severe losses in agricultural production. RNA is an important genetic material, thus the isolation and purification of RNA samples is a key step for elucidating the mechanisms of gene expression and regulation in Xcc. However, Xcc can produce more exopolysaccharides and xanthomonadin than many other bacteria; the isolation of high quality RNA from this bacterium is difficult. There is no an efficient method for isolating high quality RNA from Xcc. In this study, a simple and effective method for extracting total RNA from Xcc was established. The isolated RNA sample was determined in integrity and purity by using formaldehyde agarose gel electrophoresis and UV spectrophotometer and was found to be suitable for constructing cDNA library and screening differential expressed genes by RT-PCR or microarray analysis.