Recombination and genetic differentiation among natural populations of the ectomycorrhizal mushroom Tricholoma matsutake from southwestern China

Abstract

Effective conservation and utilization strategies for natural biological resources require a clear understanding of the natural populations of the target organisms. Tricholoma matsutake is an ectomycorrhizal mushroom that forms symbiotic associations with plants and plays an important ecological role in natural forest ecosystems in many parts of the world. It is also an economically very important gourmet mushroom. Because no artificial cultivation is available, natural populations of this species are under increasing threats, primarily from habitat disturbance and destruction. Despite its economical and ecological importance, little is known about its genetics and population biology. Here, using 14 polymerase chain reaction-restriction fragment length polymorphism markers, we analysed 154 strains from 17 geographical locations in southwestern China, a region where over 25% of the global T. matsutake harvest comes from. Our results revealed abundant genetic variation within individual populations. The analyses of gene and genotype frequencies within populations indicated that most loci did not deviate from Hardy-Weinberg equilibrium in most populations and that alleles among loci were in linkage equilibrium in the majority of the local populations. These results are consistent with the hypothesis that sexual reproduction and recombination play an important role in natural populations of this species. Our analyses indicated low but significant genetic differentiation among the geographical populations, with a significant positive correlation between genetic distance and geographical distance. We discuss the implications of our results to the ecology and resource management of this species.

Isolation by landscape in populations of a prized edible mushroom Tricholoma matsutake

“…Conversely, studies at a larger geographic scale include examples of structure: Bergemann and Miller (2002) found F st values as high as 0.434 in populations of Russula brevipes separated by over 1,500 km, although they raised the possibility that these populations may represent separate cryptic species. Likewise a study of Tricholoma matsutake by Xu et al (2008) found F st values ranging from 0.016 to 0.232 in seventeen populations (which partially overlap this study) separated by \50 km-[1,100 km.…”

DNA-based geographic typing of the gourmet mushroom Tricholoma matsutake traded in China

“…Right-hand labels indicate signature DNA fragments corresponding to SW (273 bp) and NE (493 and 337 bp) Chinese matsutake samples regions, a large and unsaturated market in Japan, expanding popularity within China, and the shrinking supply of matsutake in Japan, China, and Europe (Arnolds 1991;Wang and Hall 2004;Xu et al 2001Xu et al , 2008. Whether this traceability system is broadly applicable to other matsutake production areas both within and outside Asia remains to be determined.…”

“…This species is distributed in Europe, North America, and Asia (Xu et al 2001(Xu et al , 2008Chapela and Garbelotto 2004;Murata et al 2008). Matsutake collected from different parts of the world are priced very differently in Japan-the world's preeminent consumer market-from less than US$100 to more than US$4000/kg (Murata et al 2008).…”

“…This region produces about 500-600 tons per year with the majority exported to Japan (Xu et al 2001;Ge 2004). The SW Chinese matsutake is distributed in eastern Tibet and western parts of Yunnan and Sichuan provinces (Xu et al 2008). This region produces about 1500 tons per year, with 1100-1300 tons exported to Japan (Zhang 2004).…”

“…The authentic samples were collected by us and our collaborators directly from their natural habitats. The sampled areas spanned almost the entire matsutake distribution range in both NE and SW China (Xu et al 2001(Xu et al , 2008. The genotypes of all 373 isolates were determined using a recently described polymerase chain reaction (PCR) genotyping system based on specific primers targeting the gypsy-type retroelements (Murata et al 2008).…”