黄瓜初花期与结瓜期叶片可培养内生细菌多样性研究

摘要

[目的]研究黄瓜初花和结瓜两个生长期叶片可培养内生细菌的多样性.[方法]采用叶片表面消毒、菌种分离、16S rDNA序列扩增和系统发育分析进行了系统研究.[结果]两时期黄瓜内生细菌的种类、数量及优势菌的种类都有明显差异.初花期叶片含菌量为(2.6±0.18)×106 CFU/g鲜重,分离出的38株内生细菌分别属于短小杆菌属(Curtobacterium sp.)、节杆菌属(Arthrobacter sp.)、微杆菌属(Microbacterium sp.)等14个已知属,其中优势种类为短小杆菌属菌株；结瓜期叶片含菌量为(5.2±0.42)×105 CFU/g鲜重,分离出的43株内生菌分别属于泛菌属(Pantoea sp.)、假单胞菌属(Pseudomonas sp.)、芽孢杆菌属(Bacillus sp.)等11个已知属,其中优势种类为泛菌属菌株.[结论]初花期内生菌含量是结瓜期的5倍,两时期内生菌的种类表现出很强的差异,体现出黄瓜不同生育期可培养内生菌数量和种类的多样性,相关研究为黄瓜促生内生细菌的理论探索和生产应用提供一定的研究基础.%[Objective) The aim of this study is to explore the quantity and diversity of cultur-able endophytic bacteria in cucumber leaves sampled at blossoming and fruiting stages. [Methods] Leaf surface disinfection, strain isolation, 16S rDNA amplification and phyloge-netic analysis were used in this study. [Results] It is found that there is a significant difference in the bacterial quantity and species at two stages. At blossoming stage, the isolated bacteria belong to 14 genera, including Curtobacterium sp., Arthrobacter sp., Microbacterium sp., etc. The isolating quantity is (2.6±0.18)×l06 CFU/g fw, with Curtobacterium sp. being the dominant strain. However, at fruiting stage, the isolated bacteria belong to 11 genera, including Pantoea sp., Pseudomonas sp., Bacillus sp., etc. The isolating quantity is (5.2±0.42)xl05 CFU/g fw, with Pantoea sp. being the dominant strain. [Conclusion] The species of endophytic bacteria at these two stages were quite different. The quantity of endophytic bacteria at fruiting stage was examined to be four-fold higher than that at blooming stage. These data indicate a significant diversity in culturable bacterial species at two different growth stages. Some strains obtained from this work provide possibility for further endophyte-cucumber association mechanism study and even field application perspectives.