Metatranscriptomic analysis of ectomycorrhizal roots reveals genes associated with Piloderma-Pinus symbiosis: improved methodologies for assessing gene expression in situ.

Journal Article

Ectomycorrhizal (EM) fungi form symbiotic associations with plant roots that regulate nutrient exchange between forest plants and soil. Environmental metagenomics approaches that employ next-generation sequencing show great promise for studying EM symbioses; however, metatranscriptomic studies have been constrained by the inherent difficulties associated with isolation and sequencing of RNA from mycorrhizae. Here we apply an optimized method for combined DNA/RNA extraction using field-collected EM fungal-pine root clusters, together with protocols for taxonomic identification of expressed ribosomal RNA, and inference of EM function based on plant and fungal metatranscriptomics. We used transcribed portions of ribosomal RNA genes to identify several transcriptionally dominant fungal taxa associated with loblolly pine including Amphinema, Russula and Piloderma spp. One taxon, Piloderma croceum, has a publically available genome that allowed us to identify patterns of gene content and transcript abundance. Over 1500 abundantly expressed Piloderma genes were detected from mycorrhizal roots, including genes for protein metabolism, cell signalling, electron transport, terpene synthesis and other extracellular activities. In contrast, Piloderma gene encoding an ammonia transporter showed highest transcript abundance in soil samples. Our methodology highlights the potential of metatranscriptomics to identify genes associated with symbiosis and ecosystem function using field-collected samples.

Full Text

Duke Authors

Cited Authors

  • Liao, H-L; Chen, Y; Bruns, TD; Peay, KG; Taylor, JW; Branco, S; Talbot, JM; Vilgalys, R

Published Date

  • December 2014

Published In

Volume / Issue

  • 16 / 12

Start / End Page

  • 3730 - 3742

PubMed ID

  • 25186788

Electronic International Standard Serial Number (EISSN)

  • 1462-2920

International Standard Serial Number (ISSN)

  • 1462-2912

Digital Object Identifier (DOI)

  • 10.1111/1462-2920.12619

Language

  • eng