转Bt基因棉花根际细菌与古菌群落结构分析

在一年内棉花的四个生长时期（苗期,蕾期,花铃期,吐絮期）分别采集转Bt基因抗虫棉GK12和非转基因亲本棉花泗棉3号根际土壤,以及未种植棉花的背景土壤,利用末端标记限制性片段长度多态性（T-RFLP）分析技术,分析三种土壤中细菌和古菌的16S rRNA基因片段多态性,结合克隆文库建立和测序,研究了土壤中细菌和古菌群落结构的变化.结果表明：在棉花生长的各个时期,背景土壤中细菌群落结构发生了明显的变化,生物多样性指数明显降低,古菌群落结构也有一定的变化,说明季节性变化对土壤中微生物群落产生了明显的影响.与背景土壤相比,棉花种植后根际土壤中细菌和古菌群落发生显著的变化.转基因棉花与非转基因棉花相比,根际土壤细菌和古菌的种类和种群大小的分布也发生了明显的改变.克隆文库和测序结果表明土壤中主体微生物为目前未培养的、功能特性未知的细菌和古菌,转基因棉花种植对这些细菌和古菌影响的原因、环境危害和生态风险目前尚不清楚.与古菌群落相比,棉花种植对细菌群落结构的影响较小.

BACTERIAL AND ARCHAEAL COMMUNITY STRUCTURE IN RHIZOSPHERE SOIL PLANTING Bt TRANSGENETIC COTTON

Impact of genetically modified or transgenic plants on the eco-environment has aroused great concerns.But little is known of their possible impacts on non-target organisms,such as microbial communities associated with their parent plants in the soil environment because of the complex structure-function relationships of microorganisms.A one-year field study was carried out by analyzing soil samples collected from the cotton field and the rhizospheres of cotton plants of transgenic cotton variety GK12(expressing Bacillius thuringiensis insecticidal proteins)and its non-transgenic parent variety Simian No.3 at four different growth phrases(seedling,squaring,flowering and boll-forming,and boll-opening).Based on amplification of 16S rDNA retrieved from the soil microbial communities associated with both transgenic and non-transgenic cottons,terminal restriction fragment length polymorphism(T-RFLP)analysis,clone library construction and sequencing were carried out to see changes in bacterial and archaeal community structures in the soils.Shannon-Wiener index analysis showed that bacterial diversity declined and a certain change occurred in archaeal diversity as well in bulk soil,indicating microbial communities were affected by season succession.According to the clone library and sequencing analysis,the dominant microorganisms in the soil were bacteria and archaea that have never been cultivated or known for their functions in the soil ecosystem.It remains unclear what causes these differences and whether these differences have any ecological threats and bio-risk to the soil ecosystem.Compared to bulk soil samples,the rhizosphere soil samples showed cultivation of cotton varieties remarkably affected bacterial and archaeal communities therein.Variation of bacterial and archaeal communities,especially the archaeal community,was significantly associated with both cotton variety and growth season in T-RFLP analysis,.Since archaeal community is less diversified than bacterial community,the study illustrates that the impacts of transgenic cotton on soil microorganisms varied with the microbial background and transgenic cotton affected the less diversified microbial community more.