不同生境下五唇兰根部可培养内生细菌多样性研究

兰科植物内生细菌与菌根真菌的协作对宿主植物的生长、抗病、抗逆及植物修复环境能力等具有重要意义,揭示其内生细菌多样性及与生境之间的关系有助于阐明兰科植物的适应与进化机制。本研究基于16SrDNA序列分析探讨了不同生境下东南亚特有种五唇兰根部可培养内生细菌多样性及其空间异质性。结果表明:从不同生境下五唇兰根部共分离出内生细菌59株,其中从土生型五唇兰根部分离出内生细菌45株(76.27%),从石生型五唇兰根部分离出内生细菌14株(23.73%);基于内生细菌16SrDNA序列同源性分析及构建的系统发育树显示,五唇兰根部内生细菌分属于7属,即芽孢杆菌属(Bacillus)、伯克氏菌属(Burkholderia)、草酸菌属(Pandoraea)、土壤杆菌属(Agrobacterium)、类芽孢杆菌属(Paenibacillus)、泛菌属(Pantoea)、欧文氏菌属(Erwinia),其中优势属为芽孢杆菌属,次优势属为泛菌属和伯克氏菌属;多样性分析显示,土生型五唇兰根部内生细菌群落的Shannon多样性指数大于石生型五唇兰,不同生境下五唇兰根部内生细菌群落结构差异极显著(P0.01)。土生型五唇兰根部内生细菌群落优势属为芽孢杆菌属和泛菌属,石生型五唇兰根部内生细菌群落优势属为芽孢杆菌属和伯克氏菌属。

Diversity of Culturable Endophytic Bacteria Isolated from the Root Tissues of Phalaenopsis pulcherrima in Two Different Habitats

Orchid entophytic bacteria and mycorrhizal fungi grown in collaboration can have a positive effect on host plants in terms of disease resistance, stress tolerance and phytoremediation. Understanding the endogenous relationship between bacterial diversity and habitat can reveal the adaptation and evolution mechanisms of orchid plants. The endogenous bacterial diversity and spatial heterogeneity in different habitats of Phalaenopsis pulcherrima, an endemic Southeast Asian orchid species, were analysed by molecular techniques. Fifty-nine strains of entophytic bacteria were isolated from the roots of P. pulcherrima in different habitats, including forty-five (76.27%) and fourteen (23.73%) strains of entophytic bacteria isolated from land-borne and stone-borne type populations, respectively. Based on 16S rDNA sequence analysis, fifty-nine strains of entophytic bacteria isolated from P. pulcherrima were classified into seven genera, that was, Bacillus, Burkholderia, Pandoraea, Agrobacterium, Paenibacillus, Pantoea, and Erwinia. Among the entophytic bacterial strains, Bacillus was the dominant genus, followed by Pantoea and Burkholderia. The diversity index of land-borne type populations was greater than that of stone-borne type populations. Analysis of molecular variance (AMOVA) also showed that the entophytic bacterial community structures of P. pulcherrima in distinct habitats were significantly different (P < 0.01), with land-type dominant species found in Bacillus and Pantoea, and stone-type dominant species found in Bacillus and Burkholderia.