Gene Transcription in Lactarius quietus - Quercus petraea Ectomycorrhizas from a Forest Soil

Abstract

Extracting fungal mRNA from ectomycorrhizas (ECMs) and forest soil samples for monitoring in situ metabolic activities is a significant challenge when studying the role of ECMs in biogeochemical cycles. A robust, simple, rapid, and effective method was developed for extracting RNA from rhizospheric soil and ECMs by adapting previous grinding and lysis methods. The quality and yield of the extracted RNA were sufficient to be used for reverse transcription. RNA extracted from ECMs of Lactarius quietus in a 100-year-old oak stand was used to construct a cDNA library and sequence expressed sequence tags. The transcripts of many genes involved in primary metabolism and in the degradation of organic matter were found. The transcription levels of four targeted fungal genes (glutamine synthase, a general amino acid transporter, a tyrosinase, and N-acetylhexosaminidase) were measured by quantitative reverse transcription-PCR in ECMs and in the ectomycorrhizospheric soil (the soil surrounding the ECMs containing the extraradical mycelium) in forest samples. On average, levels of gene expression for the L. quietus ECM root tips were similar to those for the extraradical mycelium, although gene expression varied up to 10-fold among the samples. This study demonstrates that gene expression from ECMs and soil can be analyzed. These results provide new perspectives for investigating the role of ectomycorrhizal fungi in the functioning of forest ecosystems.

Fungi Unearthed: Transcripts Encoding Lignocellulolytic and Chitinolytic Enzymes in Forest Soil

“…Transcriptional down-regulation of relevant fungal genes cannot be excluded, but to assess its contribution would require large-scale application of real-time PCR as used for single specific genes from a forest soil [10]. We do provide evidence suggesting that increased nitrogen deposition induced changes in the composition of the fungal community: only 22 of the 234 detected transcripts were found in both nitrogen-supplemented and control plots, the remainder being potentially unique to one or the other.…”

Genome-Wide Approaches toward Understanding Mycotrophic Trichoderma Species

“…In this sense, genomic-based analyses of the ectomycorrhizal symbiosis in environmental settings are in their infancy (Courty et al, 2008), and have not begun in Trichoderma. Nevertheless, we should take into consideration that research in environmental genomics is rapidly developing.…”

“…One key step for the future of research with plant symbionts is the production of additional sequenced genomes, both for a variety of fungi and for their plant hosts. To date, considering four Trichoderma genomes, and those of the basidiomycete Laccaria bicolor (Martin et al, 2008) and the ascomycete Tuber melanosporum , the genomes of six symbionts have been sequenced. Based on the comparison of the symbiosis-related gene networks of the twoectomycorrhizal fungi, evolution of this lifestyle appears to be quite divergent (Plett and Martin, 2011).…”

“…Presently, however, there is a significant bias toward species that are pathogens of humans. Nevertheless, many of the fungi whose genomes have been sequenced are residents of soil and plants (Martinez et al, 2004(Martinez et al, , 2009Martin et al, 2008Ohm et al, 2010;Spanu et al, 2010;Stajich et al, 2010) and their genome sequences will constitute the baseline to explore the genomes and functions of thousands of soil fungal species that cannot be cultured and sequenced directly.…”

Saprotrophic capabilities as functional traits to study functional diversity and resilience of ectomycorrhizal community

“…Neville et al 2002;Baier et al 2006). In a recent study, we showed that the EM root tips are more abundant in the superWcial horizon than in deeper soil horizons (Courty et al 2008a; Fig. 1) and that some EM fungi (i.e.…”