华北落叶松树皮表面细菌群落多样性及其分布格局

Diversity and distribution pattern of bacterial community on bark surface of Larix principis-rupprechtii

摘要:

附生在树皮表面的微生物，对于宿主植物的健康和环境适应性发挥重要作用，树皮微生境中微生物群落结构和多样性及其维持机制有待关注。[目的] 本文对庞泉沟自然保护区不同海拔梯度的华北落叶松树干的背阴面与向阳面的树皮表面细菌群落的分布特征和适应机制进行了研究。[方法] 通过PCR-DGGE和高通量测序技术研究细菌群落特征，对树皮表面细菌群落的空间分布特征进行了非度量多维尺度（NMDS）排序分析，通过冗余分析（RDA）研究细菌群落与树皮表面理化性质的关系，单因素方差分析（One-way ANOVA）比较树皮背阴面与向阳面细菌群落组成，基于零偏差分析研究背阴面与向阳面细菌群落构建的驱动因素。[结果] 不同海拔梯度间的细菌群落结构有显著性差异（ANOSIM；P<0.05），树皮表面的微环境因子pH和总碳（TC）与群落结构显著相关（P<0.05）；向阳面树皮表面的光合自养型细菌（隶属于蓝细菌门的未命名的目）的相对丰度显著高于背阴面，而根瘤菌目的相对丰度呈相反的趋势，光照可能是引起细菌群落结构发生变化的驱动因子；零偏差分析结果表明，华北落叶松树皮背阴面、向阳面细菌群落的多样性格局主要受环境过滤的影响。[结论] 环境因子主导的确定性过程是驱动该地区华北落叶松树皮表面细菌群落结构和多样性的主导因素。

Abstract:

Epiphytic microorganisms on the bark surface play an important role in host plants' health and adaptability. The maintenance mechanism of microbial community structure and diversity in bark microhabitats need attention. [Objective] We studied the distribution characteristics and fitness mechanisms of the bacterial community on the bark surface of Larix principis-rupprechtii along elevation gradients and light in Pangquangou Natural Reserve.[Methods] By using PCR-DGGE and high-throughput sequencing technology, we studied the structure of bacterial community. By using nonmetric multidimensional scaling (NMDS) ordination, we analyzed the spatial distribution characteristic of bacterial community. By using redundancy analysis, we analyzed the relationship between bacterial community and environmental factors and by using One-way ANOVA, we compared bacterial community composition between sunny and shady surface. Based on zero-deviation analysis, the driving factors of bacterial community assembly on the shady and sunny surface were studied. [Results] Bacterial community structure was significantly different among elevation gradients (ANOSIM; P<0.05). The redundancy analysis showed that pH and total carbon (TC) on bark surface were significantly correlated with the community structure (P<0.05). The relative abundances of photosynthetic autotrophic bacteria (norank_Cyanobacteria) on the sunny surface were significantly higher than those on shady one, while the relative abundance of Rhizobiales showed an opposite trend. We suggested that light might be a driving factor in determining the structure of bark bacterial community. The results of zero-deviation analysis showed that the diversity pattern of the bacterial community on the bark surface was mainly affected by environmental filtration. [Conclusion] The determination processes were dominant factors in shaping the structure and diversity pattern of bacterial community on the bark surface of Larix principis-rupprechtii in this area.