Diversity of culturable entophytic bacteria in cucumber leaves at blossoming and fruiting stages

Abstract:

[Objective] The aim of this study is to explore the quantity and diversity of culturable endophytic bacteria in cucumber leaves sampled at blossoming and fruiting stages. [Methods] Leaf surface disinfection, strain isolation, 16S rDNA amplification and phylogenetic 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)′106 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)′105 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.