Dramatic Increases of Soil Microbial Functional Gene Diversity at the Treeline Ecotone of Changbai Mountain.

Congcong Shen,Yu Shi,Joy D Van Nostrand,Jizhong Zhou,Ye Deng,Zhili He,Yingying Ni,Haiyan Chu

doi:10.3389/fmicb.2016.01184

Abstract

The elevational and latitudinal diversity patterns of microbial taxa have attracted great attention in the past decade. Recently, the distribution of functional attributes has been in the spotlight. Here, we report a study profiling soil microbial communities along an elevation gradient (500–2200 m) on Changbai Mountain. Using a comprehensive functional gene microarray (GeoChip 5.0), we found that microbial functional gene richness exhibited a dramatic increase at the treeline ecotone, but the bacterial taxonomic and phylogenetic diversity based on 16S rRNA gene sequencing did not exhibit such a similar trend. However, the β-diversity (compositional dissimilarity among sites) pattern for both bacterial taxa and functional genes was similar, showing significant elevational distance-decay patterns which presented increased dissimilarity with elevation. The bacterial taxonomic diversity/structure was strongly influenced by soil pH, while the functional gene diversity/structure was significantly correlated with soil dissolved organic carbon (DOC). This finding highlights that soil DOC may be a good predictor in determining the elevational distribution of microbial functional genes. The finding of significant shifts in functional gene diversity at the treeline ecotone could also provide valuable information for predicting the responses of microbial functions to climate change.

Highlights

With the rapid development of molecular tools, great progress on microbial biogeography has been made over the past decade (Martiny et al, 2006; Green et al, 2008; Hanson et al, 2012; Zhou et al, 2016)
We found that microbial functional gene richness exhibited a dramatic increase at the treeline ecotone, but the bacterial taxonomic and phylogenetic diversity did not exhibit such a similar trend
We observed that soil bacteria exhibited no apparent elevational trend based on taxonomic diversity, which is consistent with previous reports (Fierer et al, 2011; Shen et al, 2013; Xu et al, 2014; Yuan et al, 2014)

Summary

Introduction

With the rapid development of molecular tools, great progress on microbial biogeography has been made over the past decade (Martiny et al, 2006; Green et al, 2008; Hanson et al, 2012; Zhou et al, 2016). Researchers examining biogeographic patterns are focusing on functional traits rather than just taxa (Fierer et al, 2012; Hanson et al, 2012; Fierer et al, 2013). Recent studies have focused on functional gene distribution in soil microbial communities across large-scale natural ecosystems or latitudinal gradients (Fierer et al, 2012, 2013; Shi et al, 2015). Little research has focused on the soil microbial communities at the treeline in elevational studies, until recently when Thébault et al (2014) examined these communities with phospholipid fatty acid analysis (PLFA) technique and observed close correlations between microbial taxonomic communities and nutrient availability. We do not know if microbial elevational diversity patterns will change in treeline ecotone and if microbial taxa and functional genes show the same pattern along an elevation gradient

Methods

Results

Conclusion