The arbuscular mycorrhizal fungal community response to warming and grazing differs between soil and roots on the Qinghai-Tibetan plateau.

Wei Yang,Yongchan Kim,Qiong Ding,Xinhua He,Liang-Dong Guo,Yong Zheng,Cheng Gao,Shiping Wang,Yichao Rui,Vishal Shah

doi:10.1371/journal.pone.0076447

Abstract

Arbuscular mycorrhizal (AM) fungi form symbiotic associations with most plant species in terrestrial ecosystems, and are affected by environmental variations. To reveal the impact of disturbance on an AM fungal community under future global warming, we examined the abundance and community composition of AM fungi in both soil and mixed roots in an alpine meadow on the Qinghai-Tibetan Plateau, China. Warming and grazing had no significant effect on AM root colonization, spore density and extraradical hyphal density. A total of 65 operational taxonomic units (OTUs) of AM fungi were identified from soil and roots using molecular techniques. AM fungal OTU richness was higher in soil (54 OTUs) than in roots (34 OTUs), and some AM fungi that differed between soil and roots, showed significantly biased occurrence to warming or grazing. Warming and grazing did not significantly affect AM fungal OTU richness in soil, but warming with grazing significantly increased AM fungal OTU richness in roots compared to the grazing-only treatment. Non-metric multidimensional scaling analysis showed that the AM fungal community composition was significantly different between soil and roots, and was significantly affected by grazing in roots, whereas in soil it was significantly affected by warming and plant species richness. The results suggest that the AM fungal community responds differently to warming and grazing in soil compared with roots. This study provides insights into the role of AM fungi under global environmental change scenarios in alpine meadows of the Qinghai-Tibetan Plateau.

Highlights

Arbuscular mycorrhizae (AM) are symbiotic associations between plant roots and soil fungi of the Phylum Glomeromycota [1]
AM root colonization ranged from 34.8 ± 7.2% to 45.1 ± 5.7%, spore density from 13.6 ± 4.2 to 30.8 ± 15.3, and extraradical hyphal (ERH) density from 1.27 ± 0.16 to 1.34 ± 0.37 (m g-1 DW) amongst the C, W, G and with grazing (WG) treatments
These 632 AM fungal sequences were grouped into 65 operational taxonomic units (OTUs) according to the 93% similarity threshold and identified as different taxonomic groups based on the phylogenetic analyses (Figure S1, Table S2)

Summary

Introduction

Arbuscular mycorrhizae (AM) are symbiotic associations between plant roots and soil fungi of the Phylum Glomeromycota [1]. Temperature manipulation studies have shown that warming affects plant productivity, diversity and community composition [10,11], and AM fungal community structure and function in ecosystems [12,13]. Warming showed positive effects on extraradical hyphal (ERH) density [14,17] and spore density [15], but a negative effect on vesicle density [18] or no effect on AM fungal community composition [12]. Such varying observations suggest that AM fungi do not always respond consistently to temperature variation

Methods

Results

Conclusion