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

Abstract

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.

Experimental evidence that fungal symbionts of beetles suppress wood decay by competing with decay fungi

“…We also obtained cultures of two species of widely distributed and abundant fungi that are pioneer colonizers that aggressively decay pine wood to examine interactions between beetle-associated fungi and wood decay fungi; one white rotter, Ganoderma curtisii f. sp. meredithiae (hereafter referred to as G. curtisii; Loyd et al 2018a) and one brown rotter (Phaeolus schweinitzii). The isolates were cultured from small pieces (<1cm 3 ) of context tissue from inside the basidiomata of each wood decay fungus as described in Loyd et al (2018b)…”

Peer Review #1 of "Insight into plant cell wall degradation and pathogenesis of Ganoderma boninense via comparative genome analysis (v0.1)"

“…Pectin degradation by pectinolytic enzymes particularly PL4 is common among necrotizing fungi examined in this study except G. boninense NJ3 and this enzyme had been shown to be highly expressed during crops infection by necrotrophic Rhizoctonia solani (Zheng et al, 2013;Chang et al, 2016). Although important for cell wall degradation by fungi, the smaller amount of pectinases in G. boninense NJ3 may indicate substrate or host preference specifically monocotyledon-type as compared to dicotyledonpreferred pathogens that have been associated with increased secretion of pectinases (Zhao et al, 2013;Loyd et al, 2018). Hemibiotrophic and necrotrophic fungi are well-equipped with the extended set of CWDEs which enable tailored and extensive production of the cell wall degrading enzymes during infection.…”

Ganoderma (Ganodermataceae, Basidiomycota) species from the Greater Mekong Subregion

“…This fungus is characterized by a laccate and concentric yellowish red pileus, stipitate, fan-shaped, sulcated with a yellow margin, ovoid, verrucose, and truncated basidiospores. Ganoderma tsugae is widely distributed across the USA (Gilbertson and Ryvarden, 1986;Loyd et al 2018). The phylogenic analysis supported G. (fan-shaped) when seen from above, broadly attached, radial from the center extending to the margin, tough to break when dried, thick at the base, slightly soft at the margin when mature, light in weight with woody or corky when dried.…”

“…multipileum (Hou 1950), G. oregonense (Murrill 1902), G. resinaceum (Patouillard 1889), G. tsugae, G. lingzhi, G. lucidum, G. sichuanense, andG. sinense (Zhao et al 1983;Pilotti et al 2004;Zhou et al 2008;Wang et al 2009;Cao et al 2012;Dai et al 2017;Loyd et al 2018) from China. Cao et al (2012) has clarified a different new species, Chinese G. lucidum as G.…”

“…tsugae as an independent species distinct from G. lucidum, as it grows exclusively on conifers, especially on Tsuga and Abies species, while G. lucidum inhabits mostly angiospermous trees(Zhou et al 2015). According toLoyd et al (2018), G. tsugae is similar to G. oregonense as they share a distinctly white context tissue, rough basidiospores, and are predominately associated with conifers decay.…”