Xiao-Lan He

Phylogenetic relationship of two popular edible Pleurotus in China, Bailinggu (P. eryngii var. tuoliensis) and Xingbaogu (P. eryngii), determined by ITS, RPB2 and EF1α sequences

The aims of this study are to assess the utility of the internal transcribed spacer (ITS) region, and partial translation elongation factor (EF1α) and RNA polymerase II (RPB2) genes, for differentiation of Bailinggu, P. eryngii, and P. nebrodensis; to reconstruct phylogenetic relationships between the three species; and to confirm the taxonomic status of Bailinggu based on ribosomal and protein-coding genes. Pairwise genetic distances between Bailinggu, P. eryngii, and related Pleurotus strains were calculated by using the p-distance model, and molecular phylogeny of these isolates was estimated based on ITS, RPB2, and EF1α using maximum parsimony and Bayesian methods. Differences in ITS, RPB2, and EF1α sequences show that Bailinggu, P. eryngii, and P. nebrodensis are distinct at the species level. Phylogenetic analyses reveal that P. eryngii is closer to P. nebrodensis than to Bailinggu. Sequence analyses of ribosomal and protein-coding genes confirm that P. eryngii var. tuoliensis is identical to Bailinggu. P. eryngii var. tuoliensis should be raised to species level or a new name should be introduced for Bailinggu after a thorough investigation into Pleurotus isolates from Ferula in Xinjiang Province. This study helps to resolve uncertainty regarding Bailinggu, P. eryngii and P. nebrodensis, improving the resource management of these strains. ITS, EF1α, and RPB2 sequences can be used to distinguish Bailinggu, P. eryngii and P. nebrodensis as three different species, and P. eryngii var. tuoliensis should be the scientific name for Bailinggu at present.

Intra- and inter-isolate variation of ribosomal and protein-coding genes in Pleurotus : implications for molecular identification and phylogeny on fungal groups

BackgroundThe internal transcribed spacer (ITS), RNA polymerase II second largest subunit (RPB2), and elongation factor 1-alpha (EF1α) are often used in fungal taxonomy and phylogenetic analysis. As we know, an ideal molecular marker used in molecular identification and phylogenetic studies is homogeneous within species, and interspecific variation exceeds intraspecific variation. However, during our process of performing ITS, RPB2, and EF1α sequencing on the Pleurotus spp., we found that intra-isolate sequence polymorphism might be present in these genes because direct sequencing of PCR products failed in some isolates. Therefore, we detected intra- and inter-isolate variation of the three genes in Pleurotus by polymerase chain reaction amplification and cloning in this study.ResultsResults showed that intra-isolate variation of ITS was not uncommon but the polymorphic level in each isolate was relatively low in Pleurotus; intra-isolate variations of EF1α and RPB2 sequences were present in an unexpectedly high amount. The polymorphism level differed significantly between ITS, RPB2, and EF1α in the same individual, and the intra-isolate heterogeneity level of each gene varied between isolates within the same species. Intra-isolate and intraspecific variation of ITS in the tested isolates was less than interspecific variation, and intra-isolate and intraspecific variation of RPB2 was probably equal with interspecific divergence. Meanwhile, intra-isolate and intraspecific variation of EF1α could exceed interspecific divergence. These findings suggested that RPB2 and EF1α are not desirable barcoding candidates for Pleurotus. We also discussed the reason why rDNA and protein-coding genes showed variants within a single isolate in Pleurotus, but must be addressed in further research.ConclusionsOur study demonstrated that intra-isolate variation of ribosomal and protein-coding genes are likely widespread in fungi. This has implications for studies on fungal evolution, taxonomy, phylogenetics, and population genetics. More extensive sampling of these genes and other candidates will be required to ensure reliability as phylogenetic markers and DNA barcodes.

White mold on cultivated morels caused by Paecilomyces penicillatus

Abstract Morchella (morel) includes prized edible and medical mushrooms in the world. Since 2012, commercial cultivation of morels in the field has developed rapidly in China. However, coupled with the rapid expansion of morel cultivation, diseases have been become serious threats to morel production. White mold is one of the most serious diseases on cultivated morels. This study aimed to confirm this pathogen by following Kochs postulates, and to identify it using molecular evidence. Our results indicated that healthy Morchella fruiting bodies inoculated with Paecilomyces sp. isolates produced typical white mold symptoms, and the internal transcribed spacer sequences of the Paecilomyces sp. were 99% similar to that recovered from an epitype of Paecilomyces penicillatus. Therefore, P. penicillatus was considered to be the causative agent of white mold. White mold occurred from the initial harvest to the storage and preservation process, and it produced white mold‐like symptoms on the caps and stripes of Morchella. This is the first time that white mold has been reported on cultivated Morchella.

Two new Entoloma s.L. species with serrulatum-type lamellar edge from Changbai Mountains, Northeast China

Two species of Entoloma with serrulatum-type lamellar edge, E. cyanostipitum and E. subcaesiocinctum from the Changbai Mountains in northeast China, are described as new. E. cyanostipitum is distinguished by a brownish orange pileus with a central depression, black-blue lamellar edge, deep blue stipe, and cylindrical cheilocystidia with intense blue, intracellular pigment. E. subcaesiocinctum is characterized by a depressed pileus covered with brownish squamules, blackish blue lamellar edge, and cylindrical to clavate cheilocystidia with intense blue intracellular pigment. The two new species are further confirmed based on the ITS and nLSU sequences.

Mushroom tumor: a new disease on Flammulina velutipes caused by Ochrobactrum pseudogrignonense.

Mushroom tumor on Flammulina velutipes has become the main disease during the off-season cultivation of F. velutipes while the causal organism has remained unknown. The present study was aimed at identifying the pathogen confirming its pathogenisity following Kochs Postulates, characterizing it using morphological, physiological, biochemical and molecular features, and studying its current distribution. We determined that mushroom tumor is a new bacterial infection disease caused by Ochrobactrum pseudogrignonense. It produces tumor-like structures on the surface of the substrate, and inhibits the formation of primordia and fruiting of F. velutipes. The molecular studies showed that this new pathogen is closely related to Ochrobactrum based on 16S rRNA sequences. This is the first time that Ochrobactrum has been shown to be a pathogen of a mushroom.

Two New Cuboid-Spored Species of Entoloma s. l. (Agaricales, Entolomataceae) from Southern China

Abstract Two cuboid-spored species of Entoloma (E. laccarioides and E. parvifructum) are described from S-China. Entoloma laccaroides is recognized by the umbilicate and whitish pileus, cuboid basidiospores, numerous conspicuous broadly fusoid to utriform pleurocystidia, cutis-like pileipellis with intracellular pigment, and presence of clamp connections. Entoloma parvifructum is characterized by the small, conico-convex and pale brown to brown pileus, comparatively large cuboid basidiospores, and cutis-like pileipellis with intracellular and encrusting pigment. The phylogenetic position and taxonomic relationships of E. laccaroides are compared and discussed with nrLSU sequences reported for various other cuboid-spored species kept in GenBank.