Enhanced Expression of Thaumatin-like Protein Gene (LeTLP1) Endows Resistance to Trichoderma atroviride in Lentinula edodes

Thaumatin-like Proteins in Legumes: Functions and Potential Applications-A Review

Thaumatin-like proteins (TLPs) comprise a complex and evolutionarily conserved protein family that participates in host defense and several developmental processes in plants, fungi, and animals. Importantly, TLPs are plant host defense proteins that belong to pathogenesis-related family 5 (PR-5), and growing evidence has demonstrated that they are involved in resistance to a variety of fungal diseases in many crop plants, particularly legumes. Nonetheless, the roles and underlying mechanisms of the TLP family in legumes remain unclear. The present review summarizes recent advances related to the classification, structure, and host resistance of legume TLPs to biotic and abiotic stresses; analyzes and predicts possible protein-protein interactions; and presents their roles in phytohormone response, root nodule formation, and symbiosis. The characteristics of TLPs provide them with broad prospects for plant breeding and other uses. Searching for legume TLP genetic resources and functional genes, and further research on their precise function mechanisms are necessary.

Diversity of Trichoderma species associated with green mold contaminating substrates of Lentinula edodes and their interaction

Introduction

The contamination of Trichoderma species causing green mold in substrates poses a significant obstacle to the global production of Lentinula edodes, adversely impacting both yield and quality of fruiting bodies. However, the diversity of Trichoderma species in the contaminated substrates of L. edodes (CSL) in China is not clear. The purpose of this study was to assess the biodiversity of Trichoderma species in CSL, and their interactions with L. edodes.

Methods

A comprehensive two-year investigation of the biodiversity of Trichoderma species in CSL was conducted with 150 samples collected from four provinces of China. Trichoderma strains were isolated and identified based on integrated studies of phenotypic and molecular data. Resistance of L. edodes to the dominant Trichoderma species was evaluated in dual culture in vitro.

Results

A total of 90 isolates were obtained and identified as 14 different Trichoderma species, including six new species named as Trichoderma caespitosus, T. macrochlamydospora, T. notatum, T. pingquanense, T. subvermifimicola, and T. tongzhouense, among which, T. atroviride, T. macrochlamydospora and T. subvermifimicola were identified as dominant species in the CSL. Meanwhile, three known species, namely, T. auriculariae, T. paraviridescens and T. subviride were isolated from CSL for the first time in the world, and T. paratroviride was firstly reported to be associated with L. edodes in China. Notebly, the in vitro evaluation of L. edodes resistance to dominant Trichoderma species showed strains of L. edodes generally possess poor resistance to Trichoderma contamination with L. edodes strain SX8 relatively higher resistant.

Discussion

This study systematically investigated the diversity of Trichoderma species in the contaminated substrate of L. edodes, and a total of 31 species so far have been reported, indicating that green mold contaminated substrates of edible fungi were undoubtedly a biodiversity hotspot of Trichoderma species. Results in this study will provide deeper insight into the genus Trichoderma and lay a strong foundation for scientific management of the Trichoderma contamination in L. edodes cultivation.

Characterization and expression analysis of a thaumatin-like protein PpTLP1 from ground cherry Physalis pubescens

Ground cherry, Physalis pubescens, is mainly cultivated as a fruit worldwide and popularly used as a food supplement and traditional Chinese medicine. Plants are challenged by external environmental stress and can initiate resistance to the stress through the regulation of pathogenesis-related (PR) proteins. Among PR proteins, PR-5, a thaumatin-like protein (TLP), was identified in many plants and found to be able to enhance stress resistance. However, PR-5 in ground cherry is not characterized and its expression is yet to be understood. In this study, a PR-5 protein PpTLP1 in P. pubescens was firstly identified. Analysis of the amino acid sequences revealed that PpTLP1 was highly similar to PR-NP24 identified in tomato with a difference in only one amino acid. Expression analysis indicated that the PpTLP1 gene was highly expressed in leaf while the PpTLP1 protein was tissue-specifically accumulated in cherry exocarp. Furthermore, the down-regulation of PpTLP1 in ground cherry was induced by NaCl treatment while the up-regulation was promoted by the infection of Sclerotinia sclerotiorum and Botrytis cinerea. This study will provide a new plant resource containing a TLP in Physalis genus and a novel insight for the improvement of postharvest management of ground cherry and other Solanaceae plants.

Lessons on fruiting body morphogenesis from genomes and transcriptomes of Agaricomycetes

Fruiting bodies (sporocarps, sporophores or basidiomata) of mushroom-forming fungi (Agaricomycetes) are among the most complex structures produced by fungi. Unlike vegetative hyphae, fruiting bodies grow determinately and follow a genetically encoded developmental program that orchestrates their growth, tissue differentiation and sexual sporulation. In spite of more than a century of research, our understanding of the molecular details of fruiting body morphogenesis is still limited and a general synthesis on the genetics of this complex process is lacking. In this paper, we aim at a comprehensive identification of conserved genes related to fruiting body morphogenesis and distil novel functional hypotheses for functionally poorly characterised ones. As a result of this analysis, we report 921 conserved developmentally expressed gene families, only a few dozens of which have previously been reported to be involved in fruiting body development. Based on literature data, conserved expression patterns and functional annotations, we provide hypotheses on the potential role of these gene families in fruiting body development, yielding the most complete description of molecular processes in fruiting body morphogenesis to date. We discuss genes related to the initiation of fruiting, differentiation, growth, cell surface and cell wall, defence, transcriptional regulation as well as signal transduction. Based on these data we derive a general model of fruiting body development, which includes an early, proliferative phase that is mostly concerned with laying out the mushroom body plan (via cell division and differentiation), and a second phase of growth via cell expansion as well as meiotic events and sporulation. Altogether, our discussions cover 1 480 genes of Coprinopsis cinerea, and their orthologs in Agaricus bisporus, Cyclocybe aegerita, Armillaria ostoyae, Auriculariopsis ampla, Laccaria bicolor, Lentinula edodes, Lentinus tigrinus, Mycena kentingensis, Phanerochaete chrysosporium, Pleurotus ostreatus, and Schizophyllum commune, providing functional hypotheses for ~10 % of genes in the genomes of these species. Although experimental evidence for the role of these genes will need to be established in the future, our data provide a roadmap for guiding functional analyses of fruiting related genes in the Agaricomycetes. We anticipate that the gene compendium presented here, combined with developments in functional genomics approaches will contribute to uncovering the genetic bases of one of the most spectacular multicellular developmental processes in fungi. Citation: Nagy LG, Vonk PJ, Künzler M, Földi C, Virágh M, Ohm RA, Hennicke F, Bálint B, Csernetics Á, Hegedüs B, Hou Z, Liu XB, Nan S, M. Pareek M, Sahu N, Szathmári B, Varga T, Wu W, Yang X, Merényi Z (2023). Lessons on fruiting body morphogenesis from genomes and transcriptomes of Agaricomycetes. Studies in Mycology 104: 1-85. doi: 10.3114/sim.2022.104.01.

Transcriptome analysis of Ganoderma lingzhi (Agaricomycetes) response to Trichoderma hengshanicum infection

Green mold caused by Trichoderma spp. has become one of the most serious diseases which threatening the production of Ganoderma lingzhi. To understand the possible resistance mechanism of the G. lingzhi response to T. hengshanicum infection, we examined the G. lingzhi transcript accumulation at 0, 12, and 24 h after T. hengshanicum inoculation. The gene expression analysis was conducted on the interaction between G. lingzhi and T. hengshanicum using RNA-seq and digital gene expression (DGE) profiling methods. Transcriptome sequencing indicated that there were 162 differentially expressed genes (DEGs) at three infection time points, containing 15 up-regulated DEGs and 147 down-regulated DEGs. Resistance-related genes thaumatin-like proteins (TLPs) (PR-5s), phenylalanine ammonia-lyase, and Beta-1,3-glucan binding protein were significantly up-regulated. At the three time points of infection, the heat shock proteins (HSPs) genes of G. lingzhi were down-regulated. The down-regulation of HSPs genes led to the inhibition of HSP function, which may compromise the HSP-mediated defense signaling transduction pathway, leading to G. lingzhi susceptibility. Pathway enrichment analyses showed that the main enriched pathways by G. lingzhi after infection were sphingolipid metabolism, ether lipid metabolism, and valine, leucine and isoleucine degradation pathway. Overall, the results described here improve fundamental knowledge of molecular responses to G. lingzhi defense and contribute to the design of strategies against Trichoderma spp.

Phylogenetic Analysis of Trichoderma Species Associated with Green Mold Disease on Mushrooms and Two New Pathogens on Ganoderma sichuanense

Edible and medicinal mushrooms are extensively cultivated and commercially consumed around the world. However, green mold disease (causal agent, Trichoderma spp.) has resulted in severe crop losses on mushroom farms worldwide in recent years and has become an obstacle to the development of the Ganoderma industry in China. In this study, a new species and a new fungal pathogen on Ganoderma sichuanense fruitbodies were identified based on the morphological characteristics and phylogenetic analysis of two genes, the translation elongation factor 1-α (TEF1) and the second-largest subunit of RNA polymerase II (RPB2) genes. The new species, Trichoderma ganodermatigerum sp. nov., belongs to the Harzianum clade, and the new fungal pathogen was identified as Trichoderma koningiopsis. Furthermore, in order to better understand the interaction between Trichoderma and mushrooms, as well as the potential biocontrol value of pathogenic Trichoderma, we summarized the Trichoderma species and their mushroom hosts as best as possible, and the phylogenetic relationships within mushroom pathogenic Trichoderma species were discussed.