番茄附生和内生细菌分离与群落相似性分析

Isolation and Similarity Analysis of Epiphytic and Endophytic Bacteria in Different Tissues of Tomato Plants

为了溯清番茄生境以及各组织细菌群落间的相关性,以中杂302为试材,采用传统平板培养法结合16S r RNA拷贝数分析、变性梯度凝胶电泳(DGGE)分析,对番茄根区、根际土壤以及根、茎、叶片、果实、种子等组织附生和内生细菌的数量和群落相似性进行分析。结果表明,番茄根际的细菌数量最多,根区土壤次之;番茄组织附生细菌的数量显著低于根区和根际土壤中的细菌数量;组织附生细菌中,以根部最多,茎和叶片次之;组织内生细菌的数量较附生细菌少2-4个数量级,并以根内生细菌数量最多,种子表面胶状物中数量最少。DGGE细菌群落相似度分析表明,根际与组织内生样品间的相似度显著高于根区土壤,各组织内生细菌相互间的相似度最高,尤其是根、茎和叶片,以及种子、胎座、胶状物等相邻组织内生细菌间的相似度达到0.6以上。番茄组织尤其是相邻组织间的内生细菌群落结构相似,并与根际细菌密切相关。

In order to explore the correlation among environmental,epiphytic and endophytic bacteria associated with tomato plants,tomato cultivar ‘Zhongza 302＇ was used as experimental material,and traditional plate culture method,16 S r RNA copies analysis,anddenaturing gradient gel electrophoresis（DGGE）assay were applied to clarify the quantity distribution and community similarities of thebacteria isolated from root zone soils and rhizosphere,as well as the epiphytic and endophytic bacteria in various tissues,including roots,stems,leaves,fruits and seeds. The results showed that the number of rhizospheric bacteria was the highest,followed by the bacteria inroot zone soil,and the epiphytic bacteria were much less than those from root zone soils and rhizosphere samples. Among different tissues,the number of root epiphyte was the highest,and then stem and leaf were followed. The numbers of endophytic bacteria were 2-4 orders ofmagnitude lower than those of epiphyte. Among different tissues,the endophyte from root was the most,while that from seed jelly was the least.DGGE analysis showed that the similarities between rhizosphere and other samples were higher compared to the root zone soils. The highestsimilarity was detected among endophytic samples from different tissues;especially for the adjacent tissues of roots,stems,and leaves,aswell as seeds,placenta,and seed jelly,the similarities were above 0.6. These results indicate that the endophytic bacteria communities indifferent tomato tissues are very similar,and they are closely related to the rhizosphere bacteria.