喀斯特植被演替过程土壤丛枝菌根真菌(AMF)多样性

喀斯特生态系统维持了丰富的微生物多样性,丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)结构和组成会随喀斯特植被演替而改变。以贵州贵阳花溪、毕节织金和关岭花江典型喀斯特区域按时空替代法采集了乔木林、灌木林和草本群落样地土壤,采用Illumina HiSeq分子测序技术,通过OTU聚类分析、物种注释及数据库比对,探索了喀斯特不同演替阶段土壤AMF物种多样性。结果表明:(1)喀斯特生境土壤获得球囊菌门Glomeromycota OTU为275个,分属于4目8科13属19种,属水平上AMF丰度表明根内根孢囊霉属Rhizophagus为优势属,花江拥有最高AMF丰富度,缩隔球囊霉Septoglomus constrictum、根内根孢囊霉Rhizophagus intraradices、Claroideoglomus sp. MIB8381和稀有内养囊霉Entrophospora infrequens均分布于各样地的不同植被演替阶段,为常见种。(2)AM真菌多样性Shannon指数与Simpson指数在不同演替阶段表现为花溪:乔木≈灌木草本(P0.05)、花江:灌木≈草本乔木(P0.05)、织金:乔木灌木草本,但差异不显著,Chao1和Abundance-based coverag estimator(ACE)指数表现为花江灌木≈草地乔木(P0.05)。(3)Spearman相关性分析表明土壤全磷与AMF ACE指数显著负相关,且与Chao1指数极显著负相关;速效磷与Shannon和Simpson指数显著负相关。(4)典范对应分析(Canonical Correlation Analysis,CCA)表明土壤全氮、速效氮、有机质、全磷和速效钾与AMF群落分布有显著相关性。结果表明喀斯特植被演替过程中土壤丛枝菌根真菌多样性随着演替进行或升高或降低,无一致变化规律,并与土壤理化性质关系密切,其中以磷的影响最大。

Species diversity of soil arbuscular mycorrhizal fungi in karst vegetation succession process

The karst ecosystem maintains rich microbial diversity, and the composition and structure of arbuscular mycorrhizal fungi changes with karst vegetation succession. In this experiment, we used a space-time substitution method to collect soil from tree, bush, and herb communities from Huaxi Guiyang, Zhijin Bijie, and Huajiang Guanling from a typical karst area located in Guizhou. Using Illumina HiSeq molecular sequencing technology, we performed an operation taxonomic unit (OTU) clustering analysis and compared the annotated species with those in a database to explore the soil arbuscular mycorrhizal fungi (AMF) species diversity during the different karst succession stages. There were 275 Glomeromycota OTUs in 19 species from 4 orders, 8 families, and 13 genera in the karst habitat soil. AMF abundance at the genus level showed that Rhizophagus was the dominant genus, and Huajiang had the highest AMF richness. The common species Septoglomus constrictum, Rhizophagus intraradices, Claroideoglomus sp.MIB8381,and Entrophospora infrequens were distributed at different stages of the vegetation succession at every sampling site. The Shannon and Simpson''s indices of AMF changed at the different stages of succession as follows:in Huaxi, tree/bush > herb (P < 0.05); in Huajiang, bush/herb > tree (P < 0.05); and in Zhijin, tree > bush > herb, but these relationships were not significantly different. The Chao1 and abundance-based coverage estimation (ACE) indices showed that in Huajiang, bush/herb > tree (P < 0.05). The Spearman correlation analysis showed that soil total phosphorus was significantly and negatively correlated with the ACE index of AMF, and it was negatively correlated with the Chao1 index. Available phosphorus was negatively correlated with the Shannon and Simpson''s indices. The canonical correlation analysis showed that soil total nitrogen, available nitrogen, organic matter, total phosphorus, and available potassium were significantly correlated with the community distribution of AMF. The results showed that although there was no uniform variation law, the diversity of soil AMF increased or decreased with the process of karst vegetation succession, which was closely related to the physicochemical properties of the soil, and the influence of phosphorus was the greatest.