摘要:植被及关联的土壤微生物对于维持热带珊瑚岛的生态系统功能和稳定性具有重要作用。采集了植物种植前的种植土和种植早期珊瑚砂土，以及栽植幼苗基质中的根际土和非根际土，利用扩增子测序的手段，分析其中的真菌和细菌的多样性、群落组成及变化。分析结果显示，种植土、幼苗基质中的非根际土和根际土可能是珊瑚砂土壤中微生物的重要来源，其中最主要的类群包括以担子菌门和接合菌门为代表的真菌，以及以变形菌门、酸杆菌门为代表的细菌。珊瑚砂土的真菌丰度（864.2±41.4，为每0.25 g土的物种数）显著低于来自苗基质的根际土（1086.1±64.3，P=0.014）和苗非根际土（1251.4±48.1，P < 0.001）；珊瑚砂土的细菌丰度与苗基质根际土和非根际土之间并没有显著性差异。通过对比种植土和植物种植后的珊瑚砂土的微生物群落β-多样性，也发现植物种植对真菌和细菌类群组成产生了影响；主要类群接合菌门真菌相对丰度从0.2%增加到17.4%，而伞菌纲真菌的相对丰度从20.8%下降到0.9%，β-变形菌纲细菌的相对丰度从17.7%下降到0.1%。研究结果启示，珊瑚砂土壤微生物的组成并非是对不同来源微生物进行简单的集合，其中生活史与植物关系密切的微生物类群，目前还未在珊瑚砂土壤中表现出优势分布；相反，一些在植物根际和非根际土中较少出现的微生物，在珊瑚砂土壤中则广为存在，从而说明土壤微生物群落恢复过程的复杂性。



Abstract:Vegetation and associated soil microbial community play important roles in the maintenance of the function and stability of tropical coral island ecosystems. In this study, we collected different soil samples from a tropical coral island at the preliminary stage of plant community establishment. These soil samples included bulk soils before and after plant establishment (coral sand), nutrition soils used during planting (nutrition soils), and the bulk and rhizosphere soils of the transplanted seedlings in the nursery (nursery bulk and rhizosphere soils). Using amplicon sequencing, we assessed and compared the diversity, composition, and variation of fungal and bacterial communities among the four types of soil samples. Our results showed that the nutrition soils, nursery bulk and rhizosphere soils were important sources for microbial community restoration in coral sands. The major fungal phylums in these soils included Ascomycota and Zygomycota, while the major bacterial phylums included Proteobacteria and Acidobacteria. Fungal richness was significantly lower in coral sands (864.2±41.4) than in nursery rhizosphere (1086.1±64.3, P=0.014) and nursery bulk soils (1251.4±48.1, P < 0.001). However, no significant difference in the bacterial richness was detected among these soils. The establishment of plant community also significantly altered the composition of both fungal and bacterial communities in the coral sands; the relative abundance of Zygomycota increased from 0.2% to 17.4%, Agaricomycetes decreased from 20.8% to 0.9%, and β-Proteobacteria decreased from 17.7% to 0.1%. Our results demonstrate that the process of microbial community restoration in the coral sands is not simply fulfilled by adding up microbial groups from the different soil sources; several microbial groups with lifestyles being closely associated with plants were not predominant in the coral sands. Furthermore, some microbial groups with lower relative abundances in the seedling soil samples were dominant in coral sands, suggesting that the soil microbial community restoration was complex.





PDF全文下载地址:

https://www.ecologica.cn/stxb/article/pdf/stxb201804240928