转基因抗虫棉对棉田土壤细菌数量及群落结构的影响

以转基因抗虫棉(GK12、33B)及其亲本对照(SM、5415)为材料,利用稀释平板法和基于rRNA基因PCR扩增的变性梯度凝胶电泳(DGGE)技术研究了棉田土壤中细菌数量和群落结构在转基因棉种植第一年的动态变化.结果表明:棉田土壤细菌数量随棉花生育期逐渐增加,于花铃中期达到最大值,转基因棉与其亲本之间细菌数量差异不显著.放线菌数量随生育期变化较小,转基因棉与其亲本之间在花铃中期出现显著差异.DGGE结果显示,转基因棉和亲本都存在丰富且相似的条带,聚类分析表明大多数转基因棉和亲本间条带相似性达80％以上,根据不同的生理期分成2个簇；主成分分析表明转基因棉和亲本细菌群落结构没有显著差异,但在不同生育期存在一定差异,表明生育期是影响细菌群落结构的主要因素,与聚类分析结果相吻合.研究结果初步说明转基因棉对棉田土壤细菌数量和群落结构没有显著影响.

Impact of Transgenic Cottons on the Number and Community Structure of Bacteria in the Cotton Soils

Dynamic changes of the number and community structure of bacteria in the soils of transgenic cottons(GK12 and 33B) together with their parents(SM and 5415) were systematically investigated using traditional plate counting and rRNA gene based PCR-DGGE methods.The results showed that the total number of bacteria increased with the reproductive periods of cottons,and the largest number appeared at the middle blossoming stage of cottons.No significant differences in the numbers of bacteria between transgenic cottons and their parents were found.The number of actinomycete changed little during the reproductive periods.However,significant differences were observed between the transgenic cottons and their parents at the blossoming stage.The results from PCR-DGGE showed that there were abundant and similar bands among all transgenic cottons and their parents,and the similarities between most of these samples were above 80%.Samples were divided into two clusters according to different reproductive periods.Principal components analysis showed that there were no significant differences between the transgenic cottons and their parents,while little differences were observed among different reproductive periods,which was consistent with the cluster analysis.These results indicated that reproductive period was the most important factor affecting community structure of bacteria.In our studies,it was found that transgenic cottons did not have significant impact on the number and community structure of bacteria in cotton soils.