Genetic Diversity of Dahongjun, the Commercially Important “Big Red Mushroom” from Southern China

Abstract

BackgroundIn southern China, a wild ectomycorrhizal mushroom commonly called “Dahongjun” or “Big Red Mushroom” by the local residents, has been harvested, consumed, and/or exported as an exotic food for many years. Although ecologically and economically important, very little is known about this mushroom, including its diversity and population structure.Methodology and Principal FindingsIn this study, we analyzed 122 samples from five local populations representing the known distribution ranges of this mushroom in southern China. We investigated the genetic diversity and geographic structure of this mushroom using sequences from four DNA fragments. Our analyses identified that this mushroom contained at least three divergent lineages: one corresponds to a recently described species Russula griseocarnosa from southern China and the remaining two likely represent two novel species. While these lineages were prominently structured geographically based on ITS sequences, evidence for ancient and/or recent gene flow was also identified within individual lineages. In addition, a local population from Ailaoshan in central Yunnan Province where 85 of our 122 specimens came from showed clear evidence of recombination.Conclusion and SignificanceThe ectomycorrhizal mushroom “Dahongjun” from southern China is a species complex with at least three divergent lineages. These lineages are largely geographically structured and there is evidence for recombination in nature. Our results indicate mature Dahongjun mushrooms with abundant basidiospores are important for the reproduction of this mushroom in nature and that individual populations of this species should be managed separately.

Recent advances in population genetics of ectomycorrhizal mushroomsRussulaspp.

“…Instead, other types of analyses such as phylogenetics and tree networks are necessary to help with species delineation and infer population level processes. As shown in Li et al (2010), the analysis of multilocus sequence data helped define several cryptic species within R. griseocarnosa . Only after such cryptic species are identified and sorted can population genetic studies within individual species be accurately performed.…”

“…Different from R. virescens , phylogeographic analyses among distinct populations of the Russula griseocarnosa species complex in southwestern China showed significant genetic differentiation, with three distinct geographic regions each having a different genetic population (Li et al 2010). However, evidence for limited spore dispersal and gene flow between some of the local and regional populations were also found.…”

“…Figure 1 shows two typical Russula species widely distributed in southwestern China. Aside from their ecological roles, a large proportion of Russula are edible, regarded as excellent sources of food and nutrients and contribute significantly to the local economy in some parts of the world, as shown in Figure 1(c) and 1(f) (Boa 2004; Li et al 2010; Cao et al 2013).

10.1080/21501203.2015.1062810-F0001Figure 1.Two ecologically and economically important Russula species in southwestern China.

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“…Indeed, many elements may affect the EMF ecological strategy in natural conditions, such as biological characteristics of the species, strain genotype, nutrient level, and other biotic and abiotic factors. The challenges to the dichotomous EMF division have mainly come from population genetic and molecular ecology data that are providing novel insights into specific EMF life histories (Riviere et al 2006; Li et al 2010; Douhan et al 2011; Cao et al 2013; Kleine et al 2013). In this paper, we review recent population genetics and molecular ecology of Russula spp.…”

A preliminary DNA barcode selection for the genus Russula (Russulales, Basidiomycota)

“…Wang et al after morphological and ITS-nLSU phylogenetic analyses (Wang et al 2009). More recently, the molecular analysis indicated that this "species" has three divergent lineages: one of them represents to R. griseocarnosa and the other two possibly correspond to unknown taxa (Li et al 2010b). The genus Russula is easily separated from other genera in morphology; however, morphological distinction at species level within this genus is complicated and time-consuming.…”