Diseases and pests noxious to Pleurotus spp. mushroom crops

Pathogenic invasive microbes Trichoderma pleuroticola transform bacterial and fungal community diversity in Auricularia cornea crop production system

Pathogenic invasion of Trichoderma pleuroticola profoundly altered microflora in the Auricularia cornea crop production system, impacting diversity and composition in both artificial bed-log and fruiting bodies. A more complex ecological network between the diseased and healthy bodies. Researchers still have poor knowledge about how the important agricultural relationship between the composition of the microbiome of the artificial bed-log and the fruiting bodies is infected by the pathogenic invasive microbes T. pleuroticola, but this knowledge is crucial if we want to use or improve it. Here, we investigated 8 groups (48 biological samples) across 5 growth stages of the A. cornea production system using metagenomic technology. Diseased and healthy fruiting bodies exhibited distinct microbial compositions, while core members in artificial bed-logs remained stable. Core microbiota analysis highlighted Pseudomonas and Pandoraea bacterial genera, as well as Sarocladium, Cephalotrichum, Aspergillus, and Mortierella fungal genera as biomarker species after the bodies were treated with the pathogenic invasive microbes T. pleuroticola. In diseased bodies, these core members upregulated pathways including polymyxin resistance, L-arginine degradation II, superpathway of L-arginine and L-ornithine degradation, glucose degradation (oxidative), glucose and glucose-1-phosphate degradation, promoting fruit spoilage. Our data confirm that T. pleuroticola plays an important role in the early stages of disease development in the A. cornea crop generation system. The exposed volatile core microbiome may play an important role in accelerating T. pleuroticola-induced decay of fruiting bodies.

Production of environmentally friendly attractants for the trap flies Megaselia halterata and Lycoriella ingenue parasites on edible mushrooms in Iraq

Among several tested mushroom-related materials, full-grown compost followed by fermented corn cobs and the compost were the best baits for attracting and catching of both insects M. halterata and L. ingenua. At the same time, there was no effect on attracting insects for the wheat straw, unfermented corn cobs, unfermented bran and water (control). The results proved that the highest attraction in the hunting of the two insects, M. halterata and L. ingenua, was in the treatment of cut fruit bodies for all studied A. bisporus strains, the highest number was 6.49 and 5.43 insects/bait; in the treatment of cut fruits of A.bisporus B62, respectively, At the level of mushroom species, the brown strain of A.bisporus showed the lowest attraction to the studied insects. Chopped fruit bodies and the spawn of some species/strains of oyster mushroom Pleurotus led to the highest interest in insects, followed by the treatment of mashed fruit bodies; the chopped fruits reached the highest attraction of insects for P. eryngii, the number of insects, M. halterata and L. ingenua, was 6.56 and 5.32 insects/bait, respectively. In the combination baits that were made from mixtures of the most efficient treatments resulting from the media and the fruit bodies of the A.bisporus and Pleurotus spp., the results showed that all treatments led to attracting the two insects at a rate of 4.55 - 8.7 insects/bait for M.halterata and 4.06 - 7.82 insects/bait for L. ingenue. The results also showed that there were significant differences in the reduction of both mushrooms A.bisporus and P. ostreatus infection rate by all types of tested baits; the lowest infection rates were in the combination bait treatment, resulting in 1.86 and 2.17%, respectively, compared to the control treatment (without bait) in which the infection rate was 87.3 and 91.25%, respectively. Keywords: Natural baits, Traps, Mushroom flies, Biological control.

Ewingella americana: An Emerging Multifaceted Pathogen of Edible Mushrooms

Mycopathogenic bacteria play a pivotal role in the productivity of edible mushrooms grown under controlled conditions. In this study, we carried out a comprehensive farm survey and sampling (2018 to 2021) on button mushroom (Agaricus bisporus) farms in 15 provinces in Iran to monitor the status of bacterial pathogens infecting the crop. Mycopathogenic bacterial strains were isolated from pins, stems, and caps, as well as the casing layer on 38 mushroom farms. The bacterial strains incited symptoms on mushroom caps ranging from faint discoloration to dark brown and blotch of the inoculated surfaces. Among the bacterial strains inciting disease symptoms on bottom mushroom, 40 were identified as Ewingella americana based on biochemical assays and phylogeny of 16S rRNA and the gyrB gene. E. americana strains differed in their aggressiveness on mushroom caps and stipes, where the corresponding symptoms ranged from deep yellow to dark brown. In the phylogenetic analyses, all E. americana strains isolated in this study were clustered in a monophyletic clade closely related to the nonpathogenic and environmental strains of the species. BOX-PCR-based fingerprinting revealed intraspecific diversity. Using the cutoff level of 73 to 76% similarity, the strains formed six clusters. A chronological pattern was observed, where the strains isolated in 2018 were differentiated from those isolated in 2020 and 2021. Taken together, due to the multifaceted nature of the pathogen, such a widespread occurrence of E. americana on mushroom farms in Iran could be an emerging threat for the mushroom industry in the country.

Internet of Things (IoT)-Based Environmental Monitoring and Control System for Home-Based Mushroom Cultivation

The control and monitoring of the environmental conditions in mushroom cultivation has been a challenge in the mushroom industry. Currently, research has been conducted to implement successful remote environmental monitoring, or, in some cases, remote environmental control, yet there is not yet a combination of both these systems providing live stream images or video. As a result, this research aimed to design and develop an Internet of things (IoT)-based environmental control and monitoring system for mushroom cultivation, whereby the growth conditions of the mushrooms, such as temperature, humidity, light intensity, and soil moisture level, are remotely monitored and controlled through a mobile and web application. Users would be able to visualize the growth of the mushroom remotely by video and images through the Internet. The respective sensors are implemented into the mushroom cultivation process and connected to the NodeMCU microcontroller, which collects and transfers the data to the cloud server, enabling remote access at any time through the end device with internet connection. The control algorithm regulates the equipment within the cultivational chamber autonomously, based on feedback from the sensors, in order to retain the optimum environment for the cultivation of mushrooms. The sensors were tested and compared with manual readings to ensure their accuracy. The implementation of IoT toward mushroom cultivation would greatly contribute to the advancement of the current mushroom industry which still applies the traditional cultivation approach.

Preliminary Studies on the Effects of Oyster Mushroom Spherical Virus China Strain on the Mycelial Growth and Fruiting Body Yield of the Edible Mushroom Pleurotus ostreatus

Oyster mushroom spherical virus (OMSV) is a positive-sense single-stranded RNA mycovirus which is associated with a devastating oyster mushroom die-back disease. However, little is known about its diversity, and the effects of OMSV infection on its fungal host are not well understood. In this study, we determined the nearly complete nucleotide sequence of OMSV isolated from cultivated oyster mushrooms in China. Sequence analysis suggested that the virus represents a new strain of OMSV (referred to here as OMSV-Ch). A GenBank BLAST search of the genomic sequences demonstrated that the OMSV-Ch had the highest identity (74.9%) with the OMSV from Korea (OMSV-Kr). At the amino acid-sequence level, these two strains shared 84.1% identity in putative replication protein (RP) and 94.1% identity in coat protein (CP). Phylogenetic analysis based on RP showed that OMSV-Ch clustered with OMSV-Kr, closely related to Tymoviridae. Phylogenetic analysis based on both the RP and CP showed that OMSV had a distant clade relationship with tymoviruses, marafiviruses, and maculaviruses. We obtained the OMSV-Ch-free Pleurotus ostreatus strain via single hyphal tip cultures combined with high-temperature treatment. Preliminary studies indicate that OMSV-Ch can significantly inhibit mycelial growth, cause malformations of the fruiting bodies, and reduce the yield of P. ostreatus. Co-cultivation resulted in horizontal transmission of the OMSV-Ch to a virus-cured strain. The findings of our study contribute to the prevention and control of mycoviral diseases in the future.

Pesticides in edible mushrooms in Vietnam

Maximum residue limits (MRLs) for pesticides have been established for edible mushrooms in order to control quality and ensure benefits of consumers in numerous countries, especially areas comprising Europe. In this study, by means of optimising extract purification conditions, a high sensitivity and reliability method to simultaneously determine 180 pesticides in mushrooms has been proposed. Matrix effects were minimised by combining QuEChERS extraction and a mixed mode of SPE cleaned up with different adsorbent materials after sample preparation. The method was completely validated following the requirements of SANTE/12682/2019. The LOQs ranged from 2 to 5 μg/kg, well below the MRLs as regulated by the EU (10-50 μg/kg). Both relative standard deviation of repeatability (RSD_r) and reproducibility (RSD_R) were less than 20% and recoveries varied from 70 to 120%. Therefore, this method was considered to be suitable for routine analysis of multi-pesticide residues in edible mushrooms.

Aegerolysins from the fungal genus Pleurotus - Bioinsecticidal proteins with multiple potential applications

The aegerolysin proteins ostreolysin A6, pleurotolysin A2 and erylysin A are produced by mushrooms of the genus Pleurotus. These aegerolysins can interact specifically with sphingolipid-enriched membranes. In particular, they strongly bind insect cells and to artificial lipid membranes that contain physiologically relevant concentrations of the main invertebrate-specific sphingolipid, ceramide phosphoethanolamine. Moreover, the aegerolysins permeabilise these membranes when combined with their protein partner pleurotolysin B, which contains a membrane-attack-complex/perforin domain. These aegerolysin/ pleurotolysin B complexes show strong and selective toxicity towards western corn rootworm larvae and adults and Colorado potato beetle larvae. Their insecticidal activities arise through aegerolysin binding to ceramide phosphoethanolamine in the insect midgut. This mode of membrane binding is different from those described for similar aegerolysin-based complexes of bacterial origin (e.g., Cry34Ab1/Cry35Ab1), or other Bacillus thuringiensis proteinaceous crystal toxins, which associate with protein receptors. The ability of Pleurotus aegerolysins to specifically interact with sphingolipid-enriched domains in mammalian cells can be further exploited to visualize lipid rafts in living cells, and to treat certain types of tumours and metabolic disorders. Finally, these proteins can strongly enhance fruiting initiation of P. ostreatus even when applied externally. In this review, we summarise the current knowledge of the potential biotechnological and biomedical applications of the Pleurotus aegerolysins, either alone or when complexed with pleurotolysin B, with special emphasis on their bioinsecticidal effects.

The PoV mycovirus affects extracellular enzyme expression and fruiting body yield in the oyster mushroom, Pleurotus ostreatus

Isogenic virus-cured and virus-infected fungal strains were previously obtained and compared to investigate mycoviral diseases and, specifically, the influence of viral infection on the vegetative growth of Pleurotus ostreatus. The present study demonstrated that infection with mycovirus PoV-ASI2792 (PoV) caused phenotypic and physiological changes in fungal cells and mycelia. The microscopically determined growth rate of the virus-infected strain was lower than that of the virus-cured strain, due to the conglomerate phenomenon during the mycelial growth process. An exploration of the viral effects of PoV on fruiting bodies yield showed significantly lower than that on virus-cured P. ostreatus. A colorimetric assay of polyphenol oxidase activity in the strains showed very weak activity in the virus-infected strain. To estimate the activity levels of enzymes related to the growth and fruiting body formation, the relative expression levels of genes encoding various extracellular enzymes such as Carbohydrate-Active Enzymes (CAZymes) were measured by quantitative RT-PCR. The expression levels of the assayed genes were significantly lower in virus-infected than in virus-cured P. ostreatus. Together, these results indicate that PoV infection affects the spawn growth and fruiting body formation of P. ostreatus via decreased expression and activity of some extracellular enzymes including lignocellulolytic enzymes.