中文摘要：

应用不依赖于培养的16S rRNA基因技术，揭示滑桃树根皮、茎皮以及种子伴生细菌的种类多样性，为建立伴生细菌的宏基因组文库奠定基础。基于我们新近发表的植物伴生菌富集方法，建立富集和未富集样品的全长16S rRNA基因文库，随机挑取至少100个克隆进行酶切分型并测序，根据16S rDNA的部分序列推测其所属伴生菌的种类。结果表明，所检测的细菌克隆大部分属于γ-Proteobacteria，有少量来源于α-Proteobacteria或放线菌（Actinobacteria），也包括不可培养或分类地位不明确的细菌。经过富集，16S rRNA基因文库中细菌克隆的比例和序列多样性显著增加，根皮的伴生细菌种类最为丰富，其次是成熟种子和茎皮；幼嫩种子16S rDNA文库的细菌克隆比例较小（1．18％），说明幼嫩种子的伴生菌最少。

英文摘要：

The species diversity of bacteria living in association with plant tissues was detected from different organs of Trewia nudiflora L. by a 16S rRNA gene-based cultivation-independent method. The results will be crucial to construct an ideal metagenomic library of plant-associated bacteria. Microbes of cultured- and uncultured-origin were enriched by the method developed recently in our laboratory. Nearly full-length 16S rDNA libraries were constructed from enriched and non-enriched sample DNA. From each library, more than 100 positive clones were randomly picked from the plates and were used for restriction fragment length polymorphism （RFLP） and sequence analysis, to identify their putative close phylogenetic relatives. As revealed in this study, our 16S rDNA clone libraries were dominated by γ-Proteobacteria. Some clones fell into uncultured or unclassified bacteria. A few clones of the libraries were affiliated with α-Proteobacteria or Actinobacteria. The enriched samples showed a considerably enhanced proportion of bacterium-derived clones and a wider sequence diversity of those clones. Among the organs detected, root barks are possessed of the highest diversity of bacteria; stem barks and ripe seeds are of secondly diversity of bacteria. Only 1.18% of bacterium-derived clones were found in the 16S rDNA library from young seeds, which strongly indicated that very few bacteria colonized young seeds.