A hypogeous, sequestrate, ectomycorrhizal fungus belonging to Elaphomyces was found in a Shorea plantation at Haurbentes Research Forest, West Java, Indonesia. Elaphomyces tropicalis is described as a new species based on morphological characters and molecular phylogenetic analysis of the ITS rDNA sequence. Sequences of E. tropicalis formed a distinct clade close to E. hassiacus, and sister to E. granulatus and E. asperulus. Elaphomyces tropicalis is not closely related to the E. papillatus clade. Morphologically, E. tropicalis is similar to E. (subsect Papillati) papillatus var. striatosporus with its crested spore ornamentation, but differs by having larger ascomata and different associated hosts. Shorea selanica and S. leprosula are the presumed hosts of E. tropicalis. This is the first report of an Elaphomyces species with Shorea species thus widening the previously known Elaphomyces host range.

Hymenoscyphus fraxineus causes a lethal disease known as “ash dieback” in the common ash, Fraxinus excelsior, in Europe. It is hypothesized that the fungus originated from East Asia. This fungus is found on the leaf litter of the Manchurian ash, Fraxinus mandshurica, in Japan and is reported to produce apothecia on pseudosclerotial plates formed mainly on decomposing rachises. However, dieback disease has not been reported in Japan, and little is known about the life cycle of H. fraxineus. This study was conducted to explore the behavior and life cycle of this fungus. It was revealed that, after infection by ascospores, H. fraxineus endophytically inhabits the living leaves of F. mandshurica. On fallen leaves, the fungus behaves saprophytically, producing apothecia on pseudosclerotial plates formed mainly on the decomposing rachises. Analysis by real-time quantitative polymerase chain reaction (qPCR) revealed that the amount of H. fraxineus DNA sharply increased in rachises, while such sharp increase of DNA was not found in leaflets.

The members of Proteobacteria have been frequently detected from ectomycorrhizal roots; however, their function in the my celial growth of ectomycorrhizal fungi remains uncertain. This study examined the extension of the hyphal area of Laccaria parva co-cultured with the ectomycorrhizosphere bacteria. One mycelial disk of L. parva was placed on the center of a plastic dish containing diluted modified Melin Norkrans agar media, and each bacterial strain was incubated 2 cm away from the mycelial disk at four orthogonal directions. Several strains of Rhizobiaceae, including those closely related to Bradyrhizobium, significantly increased the extension of the hyphal areas of several strains of L. parva; however, the majority of bacteria tended to decrease them. The effects of bacteria on the hyphal growth area differed according to the combination of strains of bacteria and L. parva in several cases, indicating that the interactions between bacteria and L. parva can be specific at the strain level.

Matsutake (Tricholoma matsutake) is a commercially valuable edible ectomycorrhizal mushroom. The physiological traits of T. matsutake have been previously assessed using mycelial isolates isolated from basidiomata; however, few studies have focused on basidiospores. Here, we report that sibling T. matsutake isolates generated from basidiospores on a single basidioma show distinct physiological variation. We first established 145 isolates of T. matsutake on modified Norkrans' C (MNC) agar medium and found that their radial growth varied significantly. The mycelial biomasses of nine isolates with different growth rates were reduced on low-carbon and low-nitrogen MNC media. However, the colony diam of one isolate was significantly elevated on low-carbon medium, and the colony diam of two isolates were significantly elevated on low-nitrogen medium. In co-cultures of two or three isolates, commensal and amensal interactions were observed. The physiological variation induced by low carbon and nitrogen levels and the mycelial interactions between sibling isolates imply mechanisms for the genetic and functional characteristics of mycelia of T. matsutake.

The hemibiotrophic fungus Colletotrichum orbiculare is the causal agent of anthracnose of cucumber. During host plant infection, appressoria penetrate into the host cells, and biotrophic infection hyphae elongate inside the host cells, then switch to necrotrophic phase. We found that the homeobox transcription factor CoHox1 is a novel type of pathogenesis-related gene. CoHox1 disruption mutants of C. orbiculare were non-pathogenic on host cucumber cotyledons and formed no lesions at wound sites on leaves. On artificial surfaces (glass and cellulose membrane), CoHox1 disruption mutants formed normal appressoria and infection hyphae similar to a wild-type strain. On the other hand, microscope observation showed that CoHox1 disruption mutants has a decreased rate of penetration of host leaves, and the infection hyphae of CoHox1 disruption mutants did not extend from the penetrated host cell into neighboring cells. On heat-shocked host leaves, CoHox1 disruption mutants also formed no lesions. These results showed that homeobox transcription factor CoHox1 may be required for pathogenicity, especially the morphogenesis of infection hyphae in host cells by C. orbiculare.

Swift and efficient onset of feeding on host tissue by phytopathogenic fungi is a requisite event for their successful infection and propagation. Necrotrophic fungi colonizing host cell walls appear to obtain carbon and energy sources from plant wall degradants, but what they actually utilize for nutrition after host invasion remains unclear. Here we focus on plant wall xylan, the major hemicellulosic polysaccharide in cereal plants, and study its participation in post-invasion nutrition of the maize necrotrophic pathogen Bipolaris maydis (syn: Cochliobolus heterostrophus). Using a fluorescence reporter assay, we demonstrated that a B. maydis β-xylosidase gene, BmXyp1, is strongly upregulated at the beginning of infection, specifically within invading hyphae. Additionally, our time-course measurements of mRNA expression during maize infection revealed that xylan degradation and assimilation are concomitantly induced during an early infection stage. These findings suggest that this fungus can access xylan degradants as an early in planta nutrient source after host penetration; however, mutant strains deficient in xylan-assimilation ability still retained virulence, although the lesion size was decreased as compared with the wild-type strain. Overall, we conclude that xylan degradation and assimilation by B. maydis are initial post-invasion events but do not play an essential role in fungal nutrient acquisition.

Agaricus bisporus is the most widely cultivated mushroom. The mushroom crop is subjected to several fungal diseases. Dry bubble disease caused by Lecanicillium fungicola is among notorious diseases of A. bisporus. This study aimed to assess phenotypic resistance to dry bubble disease among A. bisporus wild strains, collected from Iran regions. The reliability of resistance evaluations regarding disease incidence and intensity was well documented. The extraordinary tolerance of some wild strains to even high degrees of inoculum concentrations (10⁷ and 10⁸ spore/m² mushroom growth bed) of the pathogen in compare to commercial cultivars approved potentials of the wild germplasm in breeding programs for resistance. Also, the potential of some Microsatellite loci for the molecular-based rapid screening of tolerance was established by attributing SSR loci of phenotypically tolerant strains to QTLs for dry-bubble resistance-related traits.

Pleurotus ostreatus is one of the most important edible mushrooms. Many cultivars have been bred to meet consumer needs. The identification of cultivars based on the morphological characteristics is restricted because fruiting bodies are frequently capricious due to environmental conditions; accordingly, sequence-based methods are required. A total of 546 simple sequence repeat primers derived from the P. ostreatus genome were screened, and one primer, JHH_SSR-184, was found to show polymorphisms on the major cultivars in Korea. The sequences of the polymorphic loci showed variable-number tandem repeat loci-like features enabling cultivar specificity. Thus, these loci might be applicable to discriminate P. ostreatus cultivars.