Arbuscular mycorrhizal fungi community structure, abundance and species richness changes in soil by different levels of heavy metal and metalloid concentration

Abstract

Arbuscular Mycorrhizal Fungi (AMF) play major roles in ecosystem functioning such as carbon sequestration, nutrient cycling, and plant growth promotion. It is important to know how this ecologically important soil microbial player is affected by soil abiotic factors particularly heavy metal and metalloid (HMM). The objective of this study was to understand the impact of soil HMM concentration on AMF abundance and community structure in the contaminated sites of South Korea. Soil samples were collected from the vicinity of an abandoned smelter and the samples were subjected to three complementary methods such as spore morphology, terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE) for diversity analysis. Spore density was found to be significantly higher in highly contaminated soil compared to less contaminated soil. Spore morphological study revealed that Glomeraceae family was more abundant followed by Acaulosporaceae and Gigasporaceae in the vicinity of the smelter. T-RFLP and DGGE analysis confirmed the dominance of Funneliformis mosseae and Rhizophagus intraradices in all the study sites. Claroideoglomus claroideum, Funneliformis caledonium, Rhizophagus clarus and Funneliformis constrictum were found to be sensitive to high concentration of soil HMM. Richness and diversity of Glomeraceae family increased with significant increase in soil arsenic, cadmium and zinc concentrations. Our results revealed that the soil HMM has a vital impact on AMF community structure, especially with Glomeraceae family abundance, richness and diversity.

Fig 1. Family relative abundance (FRA) of arbuscular mycorrhizal fungi in heavy metal contaminated soils.

Fig 2. Peak abundance of Terminal Restriction Fragments (T-RFs) and AMF ribotype corresponds to fragment size.

(A) AluI, (B) MboI digestion.

Fig 3. Denaturing Gradient Gel Electrophoresis (DGGE) profile of partial 18S rDNA amplification of Glomeraceae family.

S1-S4 represents the samples obtained from each site. Band numbering refers to Glomeraceae ribotypes identified by sequencing are given in fig 4.

Fig 4. Nearest BLAST match name of the dominant Glomeraceae sequences obtained from DGGE gel.

Fig 5. Regression analysis of soil As (A, B), Cd (C, D) and Zn (E, F) against Glomeraceae spore count (A, C, E), richness and diversity (B, D, F).

Square, diamond and triangle represents site 1, site 2 and site 3 respectively. In Fig 5 B,D and F the open data series represents the diversity index and the closed ones are represents the richness.