Ganoderma species complex research published today in PLoS by Andrew Loyd, PhD.

Elucidating “lucidum”: Distinguishing the diverse laccate Ganoderma species of the United States 

Ganoderma is a large, diverse and globally-distributed genus in the Basidiomycota that includes species causing a white rot form of wood decay on a variety of tree species. For the past century, many studies of Ganoderma in North America and other regions of the world have used the name G. lucidum sensu lato for any laccate (shiny or varnished) Ganoderma species growing on hardwood trees or substrates. Molecular studies have established that G. lucidum sensu stricto (Curtis) Karst is native to Europe and some parts of China. To determine the species of the laccate Ganoderma that are present in the United States, we studied over 500 collections from recently collected samples and herbarium specimens from hardwoods, conifers, and monocots. A multilocus phylogeny using ITS, tef1α, rpb1 and rpb2 revealed three well-supported clades, similar to previously reported findings. From the U.S. collections, thirteen taxa representing twelve species were identified, including: G. curtisii, G. lucidum sensu stricto, G. martinicense, G. oregonense, G. polychromum, G. ravenelii, G. sessile, G. tsugae, G. tuberculosum, G. cf. weberianum, G. zonatum, and Tomophagus colossus (syn. G. colossus). The species G. meredithiae is synonymized with G. curtisii, and considered a physiological variant that specializes in decay of pines. The designation G. curtisii f.sp. meredithiae forma specialis nov. is proposed. Species such as G. curtisii and G. sessile, once considered as G. lucidum sensu lato, were found to be divergent from one another, and highly divergent from G. lucidum sensu stricto. Morphological characteristics such as context tissue color and features (e.g. melanoid bands), basidiospore shape and size, geographic location, and host preference were found to aid in species identification. Surprisingly, G. lucidum sensu stricto was found in the U.S., but only in geographically restricted areas of northern Utah and California. These collections appear to have resulted from the introduction of this species into the United States possibly from mushroom growers producing G. lucidum outdoors. Overall, this study clarifies the chaotic taxonomy of the laccate Ganoderma in the United States, and will help to remove ambiguities from future studies focusing on the North American species of laccate Ganoderma. 

The mushroom of immortality?

New research published in Frontiers in Microbiology  questions what is really in those supplements that claim to contain Ganoderma lucidum, (otherwise known as reishi in Japan and lingzhi in China), an Asian species renown as a panacea.

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No rest for the laurels: symbiotic invaders cause unprecedented damage to southern USA forests

Laurel wilt is an extraordinarily destructive exotic tree disease in the southeastern United States that involves new-encounter hosts in the Lauraceae, an introduced vector (Xyleborus glabratus) and pathogen symbiont (Raffaelea lauricola). USDA Forest Service Forest Inventory and Analysis data were used to estimate that over 300 million trees of redbay (Persea borbonia sensu lato) have succumbed to the disease since the early 2000s (ca 1/3 of the pre-invasion population). In addition, numerous native shrub and tree species in the family are susceptible and  threatened in the Western Hemisphere. Genetic markers were used to test the hypothesis that the vector and pathogen entered North America as a single introduction. With a portion of the cytochrome oxidase I gene, a single Xglabratus haplotype was detected in the USA. Similarly, Amplified Fragment Length Polymorphisms indicated that 95% (54 of 57) of the isolates of Rlauricola that were examined were of a single clonal genotype; only minor variation was detected in three polymorphic isolates. Similar levels of disease developed after swamp bay (Ppalustris) was inoculated with each of the four genotypes of Rlauricola. It is proposed that a single founding event is responsible for the laurel wilt epidemic in the United States.

Biological Invasions, July 2017, Volume 19, Issue 7, pp 2143–2157