Volvariella volvacea is a mushroom known for its high palatability and nutritional value. However, it is susceptible to spoilage thus making it challenging to preserve and keep fresh after harvest, resulting in constraints in long-distance transportation and long-term storage. This study aimed to investigate the feasibility of using irradiation and sodium dehydrogenate (SD) as a preservative in the preservation process of V. volvacea. The effects of three treatments of 0.8 kGy 60Coγ irradiation (B), 0.04% SD (C), combined with 0.04% SD and 0.8 kGy 60Coγ irradiation (A) on the postharvest freshness of V. volvacea were investigated. The assessment indices for V. volvacea, including appearance, browning rate, weight loss, respiration rate, MDA content, antioxidant enzyme activities, vitamin C (Vc), and soluble protein content, were measured and compared. The three treatments were compared to determine the changes in storage time over 7 days post-harvest. The results demonstrated that the hardness of the fruiting body exhibited a significant increase of 81.19%, 97.96% and 168.81% in comparison to the control, B and C, respectively, following the application of the treatment A. Compared to the control group, the soluble protein content was significantly increased by 20.28%. Respiration intensity and browning rate were significantly lower in the control treatment, decreasing by 35.07% and 45.49% respectively. On the 6th day of storage, the activities of SOD and POD increased by 81.06% and 73.71%, respectively, compared to the control, which significantly delayed the senescence of the fruiting bodies. The Vc content was significantly increased by 50.27%, 133.90%, and 101.39% in treatment B, which received 0.8 kGy 60Coγ irradiation alone, compared to the control, treatment A, and treatment C, respectively. The treatment C alone significantly reduced respiratory intensity and MDA variables by 39.55% and 31.01%, respectively, compared to the control. The findings can provide theoretical references and technical support for extending the preservation period of V. volvacea after harvesting by using irradiation and sodium dehydrogenate as a preservative.

Fresh D . rubrovolvata and P . impudicus are perishable due to their high water content and strong postharvest respiration, which seriously affect their edible value and economic benefits. Drying performs the crucial role in maintaining the quality of edible fungi and extending their shelf life, while the extraction method after drying is also important to the material composition and functional properties of edible fungi. According to the color difference and texture indicators, 45 degrees C was found to be the optimal temperature choice for both hot-air and vacuum drying. In addition, polysaccharide content in the extract of dried D . rubrovolvata was higher than that of P . impudicus, while the polyphenol abundance in the extract of dried P . impudicus was better than that of D . rubrovolvata. Hot water extraction or thermal ultrasonic treatment was beneficial for the antioxidant activity in D . rubrovolvata and P . impudicus extracts. Based on the correlation analysis, it was showed that polyphenols contributed significantly more to the antioxidant capacity of D . rubrovolvata and P . impudicus, especially P . impudicus, than that of polysaccharides. The related results provided new insights into the improvement of product quality and the development of functional products for D . rubrovolvata and P . impudicus.

One of the most common harmful mites in edible fungi is Histiostoma feroniarum Dufour (Acaridida: Histiostomatidae), a fungivorous astigmatid mite that feeds on hyphae and fruiting bodies, thereby transmitting pathogens. This study examined the effects of seven constant temperatures and 10 types of mushrooms on the growth and development of H. feroniarum, as well as its host preference. Developmental time for the total immature stages was significantly affected by the type of mushroom species, ranging from 4.3 ± 0.4 days (reared on Pleurotus eryngii var. tuoliensis Mou at 28°C) to 17.1 ± 2.3 days (reared on Auricularia polytricha Sacc. at 19°C). The temperature was a major factor in the formation of facultative heteromorphic deutonymphs (hypopi). The mite entered the hypopus stage when the temperature dropped to 16°C or rose above 31°C. The growth and development of this mite were significantly influenced by the type of species and variety of mushrooms. Moreover, the fungivorous astigmatid mite preferred to feed on the 'Wuxiang No. 1' strain of Lentinula edodes (Berk.) Pegler and the 'Gaowenxiu' strain of P. pulmonarius (Fr.) Quél., with a shorter development period compared with that of feeding on other strains. These results therefore quantify the effect of host type and temperature on fungivorous astigmatid mite growth and development rates, and provide a reference for applying mushroom cultivar resistance to biological pest control.

The storage mite, Tyrophagus putrescentiae, found worldwide in many habitats, is an important pest of edible mushrooms. Excessive chemical spraying for pest control has been linked to environmental pollution, health risks, insecticide resistance development, and food safety. Host resistance can be sustainable and cost-effective and provide effective and economical pest control. Previous studies have reported that the oyster mushroom Pleurotus ostreatus has evolved effective defense mechanisms against T. putrescentiae attack, but the underlying mechanism remains unclear. Here we report that a lectin gene from P. ostreatus mycelia, Polec2, induced fungal resistance to mite grazing. Polec2 belongs to a galectin-like lectin classification, encoding a protein with β-sandwith-fold domain. Overexpression of Polec2 in P. ostreatus led to activation of the reactive oxygen species (ROS)/mitogen-activated protein kinases (MAPKs) signaling pathway, salicylic acid (SA), and jasmonate (JA) biosynthesis. The activation resulted in bursts of antioxidant activities of catalases (CAT), peroxidases (POD), superoxide dismutases (SOD), and increased production of SA, JA, jasmonic acid-isoleucine (JA-Ile) and jasmonic acid methyl ester (MeJA), accompanied by reduced T. putrescentiae feeding and suppressed its population. We also provide an overview of the phylogenetic distribution of lectins across 22 fungal genomes. Our findings shed light on the molecular mechanisms of P. ostreatus' defense against the mite predator and will be useful in investigating the molecular basis of fungi-fungivory interactions and gene mining for pest-resistance genes.

Sensory neuron membrane proteins belong to a gene family of the human fatty acid transporter CD36, which is mainly involved in the recognition of fatty acids, cholesterol, and proteinaceous compounds in cells. The gene families of the olfactory system in Acari are still not clear. In this study, we identified four SNMPs in the storage mite, Tyrophagus putrescentiae (Schrank) (Astigmata: Acaridae), named as TputSNMP1-4, and then determined these TputSNMPs expression levels in different developmental stages. All the TputSNMPs exhibited higher expression levels in the protonymph, female and male adults. To gain insight into the SNMP gene family, we surveyed the genomes of 12 other arthropod species. The results revealed that the SNMP gene family was highly dynamic in Acari, originating from the independent origins of insect subfamilies that differed from the SNMP1 group but in proximity to the SNMP2 group.

Fungal chemicals are vital in processes recognizing damage- and microbe-associated molecules (DAMPs/MAMPs) that trigger defense responses in fungi. Pleurotus ostreatus is a widely cultivated edible fungus that is prone to attack from fungivorous insects and mites. Yet P. ostreatus has evolved an elegant defense system against fungivore attacks. In this study, we investigated how the oyster mushroom responds to the fungivory and mechanical wounding by conducting transcriptome, proteome, and secondary metabolic analyses. The profiling analysis revealed a total of 11,495 transcripts and 866 proteins, 4416 differentially expressed genes (DEGs), and 62 differentially expressed proteins (DEPs) were identified in response to the mite Tyrophagus putrescentiae feeding and mechanical wounding. In comparing the responses induced by mechanical wounding, some genes, proteins, and metabolites were uniquely induced or repressed by the mite. At the transcript level, nine pathways were activated by the mite feeding, including those of "MAPK signaling pathway-yeast", "Phenylalanine metabolism", and "Biotin metabolism", among others, while both enrichment of "Ribosome", "Ribosome biogenesis in eukaryotes", and "Regulation of Mitophagy in Yeast" demonstrated the common effects upon fungal secretory protein synthesis and processing induced by fungivory and mechanical wounding. Fungivory also stimulated the synthesis of C8-aryl compounds and sesquiterpenes (especially1-octen-3-ol and α-/β-bisabolene), and these compounds repellent to T. putrescentiae. Both jasmonic acid (JA) and jasmonic acid methyl ester (MeJA) were specifically regulated by mite feeding and mechanical wounding. The terpene synthase gene transcription was significantly increased induced by the exogenous addition of MeJA, resulting in defensive sesquiterpene production against the mite. These findings are the first to demonstrate that the reactive oxygen species (ROS)/MAPK signaling pathway, JA regulation, specific gene expression, and protein synthesis, and anti-mite substance metabolism are all involved in coordinated inducible chemical-based defense responses in P. ostreatus, which could be especially effective the mite T. putrescentiae.

Abstract Strains MS586T and MS82, which are aerobic, Gram‐negative, rod‐shaped, and polar‐flagellated bacteria, were isolated from the soybean rhizosphere in Mississippi. Taxonomic positions of MS586T and MS82 were determined using a polyphasic approach. 16S rRNA gene sequence analyses of the two strains showed high pairwise sequence similarities (>98%) to some Pseudomonas species. Analysis of the concatenated 16S rRNA, rpoB, rpoD, and gyrB gene sequences indicated that the strains belonging to the Pseudomonas koreensis subgroup (SG) shared the highest similarity with Pseudomonas kribbensis strain 46‐2T. Analyses of average nucleotide identity (ANI), genome‐to‐genome distance, delineated MS586T and MS82 from other species within the genus Pseudomonas. The predominant quinone system of the strain was ubiquinone 9 (Q‐9), and the DNA G+C content was 60.48 mol%. The major fatty acids were C16:0, C17:0 cyclo, and the summed features 3 and 8 consisting of C16:1ω7c/C16:1ω6c and C18:1ω7c/C18:1ω6c, respectively. The major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, and diphosphatidylglycerol. Based on these data, it is proposed that strains MS586T and MS82 represent a novel species within the genus Pseudomonas. The proposed name for the new species is Pseudomonas glycinae, and the type strain is MS586T (accession NRRL B‐65441 = accession LMG 30275).

Oyster mushroom ( Pleurotus geesteranus Singer) is grown widely in China withut problems, but occasionally severe bacterial contamination occurred in cultivation bags of Pleurotus geesteranus during high summer temperatures in some companies in the Chunan county of Zhejiang province in 2018, belonging to the so-called Bacillus pumilus group by morphological characteristics, 16S rRNA, GyrB and aroE genes sequencing, fatty acid analysis and MALDI analysis. The inoculation tests confirmed that Bacillus pumilus strains were contaminants causing mycelial disappearance of P. geesteranus . The dual culture tests demonstrated that several strains of B. pumilus were able to inhibit mycelial growth of P. geesteranus . In order to find the sources of contamination the, process of mushroom cultivation was investigated. A 41.0% contamination rate occurred in cultivation bags with sponge plugs, as opposed to a very low contamination rate (<4%) in cultivation bags with cotton plugs. It was also shown that a 13.0% bacterial isolation rate was obtained from autoclaved sponge pieces, as opposed to 2.0% or 0.0% from cotton pieces, respectively. Fifteen strains isolated all were identified by MALDI-Biotyper as Bacillus spp., belonging to four species ( Bacillus circulans , B. pumilus , B.cereus and B. halosaccharovorans ). Dual culture tests showed that B. circulans , B. cereus and B. halosaccharovorans strains had not inhibitory effect on mycelial growth of P. geesteranus . This study furthermore shows that sponge plugs containing B. pumilus contaminants were the contamination source in cultivation bags of P. geesteranus .

The genomic sequence of Pseudomonas sp. strain MS82 isolated from the rhizosphere of a soybean plant is reported and analyzed in relation to its extensive antifungal activity. Broth media used for production of the antifungal extract from strain MS82 against the mushroom pathogen Trichoderma viride were optimized using the routine plate bioassays. Culture extract of strain 82 in the peptone–K2HPO4–MgSO4 medium (PKM; peptone 20 g/L, K2HPO4 1.5 g/L, MgSO4 1.5 g/L and sterilized water) showed the best antifungal activity with an inhibition rate of 88.69 ± 3.87% to the fungal pathogen. Control efficacy of the T. viride contamination was investigated in mushroom production compost. The disease severity index of P. ostreatus hyphae infected by T. viride of treatment mixed with MS82 supernatant (38.33 ± 5.20%) was lower than that of the compost mixed with non-inoculated broth (97.50 ± 2.50%). The multilocus sequence analysis, containing four partial sequences from the gyrB, rpoB, recA and rpoD, suggests that strain MS82 is a Pseudomonas strain. The strain MS82 genome consists of a circular chromosome of 6,207,556 bp that was predicted to encode 5401 proteins and 131 RNA genes. Genome analysis revealed the presence of the gene clusters for biosynthesis of antifungal compounds, such as phenazine, pyocyanin, pyoverdine, volatile HCN and cyclic lipopeptides (arthrofactin). Genome analysis presented in the report will provide insights into development of biological control for fungal contamination in mushroom cultivation.

The storage mite, Tyrophagus putrescentiae, found worldwide in many habitats, is an important pest of edible fungi in China. Storage mites are tiny and difficult to observe, especially when they occur in fungi composts. In this study, one gustatory receptor protein (TputGR1) was identified from the transcriptome of T. putrescentiae. Phylogenetic analysis of GRs families from 10 arthropod species revealed that TputGR1 had high homology with the SccaGR1 of Sarcoptes scabiei and TurtGR1-2 of Tetranychus urticae, but low homology with other insect species, Drosophila melanogaster, Anopheles gambiae, Bombyx mori, Aedes aegypti, Culex quinquefasciatus, and Pediculus humanus. We developed a detection system for the mite on fungi hosts using the GR protein and the loop-mediated isothermal amplification (LAMP). This procedure was rapid (60 min from sampling to result) and had high sensitivity (0.5 ng/mL). LAMP provided rapid and reliable detection of T. putrescentiae. It has good specificity for single samples and for large-scale surveys.

The bulb mite, Rhizoglyphus robini (Claparède; Astigmata: Acaridae), is a cosmopolitan pest with a broad host range, including commercially grown edible fungi in China. In this study, we recorded the development and reproductive traits of the bulb mite reared on four mushroom species: Agaricus bisporus Lange, Pleurotus ostreatus Kumm, Pleurotus pulmonarius (Fr.) Quél., and Lentinula edodes (Berk.) Pegler at six constant temperatures ranging from 15 to 31°C and 80% RH. Developmental time for the immature stages was significantly affected by fungal species, ranging from 9.45 ± 1.83 d (reared on L. edodes at 31°C) to 26.39 ± 2.10 d (reared on A. bisporus at 15°C). Edible fungi species significantly affected intrinsic rates of natural increase (rm) at 31°C (varied from 0.23 to 0.28) as did the mite's net reproductive rates (R0) (103.78, 90.43, 70.77, and 97.45, respectively). Longevity, fecundity and female lifespan were dependent on host fungi.

Many mites rely on fungi for nutrients, and fungi benefit from them with regard to spore dispersal, or nutrient resources. The interactions among mites and fungi are still not clear in most cases. This study analyzed volatile natural products from the liquid and solid cultures of the edible fungi, Flammulina velutipes (Fr.) Sing, and the solid mycelia induced by the storage mite, Tyrophagus putrescentiae Schrank, using HS-SPME-GC–MS/MS. Five new monoterpenes and 30 new sesquiterpenes were isolated from the two cultures of F. velutipes and a newly monoterpene and 14 newly sesquiterpenes found in the solid mycelia induced by the storage mite. Sesquiterpenes were abundant in the mycelial stage of F. velutipe. The mite was attracted by some volatiles from host fungi, dihydrocarveol, cedrol, β-caryophyllene, α-terpilene, β-pinene and benzaldehyde, analyzed by four-arm olfactometer. Some terpenes induced by T. putrescentiae, such as caryophyllene oxide, bicyclogermacrene, and (−)-spathulenol, would have potential biological function. These results suggest that some volatile sesquiterpenes play an important role in enabling the mite to recognize host fungi.

Bacterial strain MS82, isolated from the rhizosphere of a soybean plant, belongs to the species Pseudomonas fluorescens. The most important feature of strain MS82 is the production of antifungal activity against the mushroom pathogenic fungus Mycogone perniciosa but not against the mushroom fungus Agaricus bisporus. In this study, the mutant MS82MT19 generated with the EZ-Tn5 transposon system completely lost the antifungal activity against M. perniciosa. An open-reading frame named as PafR and predicted to code for a sensory box GGDEF/EAL domain protein, was disrupted in MS82MT19. To further confirm the function of this gene, site-directed mutagenesis with insertion of the terminatorless nptII cassette into the PafR gene was used to generate the mutant MS82SD19. As expected, there was no detectable antifungal activity of mutant MS82SD19 against M. perniciosa. These results suggest that the PafR gene plays an important role in the production of antifungal activity of P. fluorescens strain MS82.

BACKGROUND:Chemosensory proteins (CSPs) have been proposed to transport a range of aliphatic compounds, esters and other long-chain compounds. A large number of CSPs from different gene subfamilies have been identified and annotated in arthropods; however, the CSP genes in mites remain unknown. Tyrophagus putrescentiae Schrank is an important stored-product and house-dust pest.RESULTS:By analysing the transcriptome, two putative CSPs were identified, namely TputCSP1 and TputCSP2 (14.9 kDa and 12.1 kDa respectively). The phylogenetic tree showed that the two TputCSPs shared most homology with CSPs in Ixodes scapularis and partially with Diptera, including Anopheles gambiae, Drosophila melanogaster, D. pseudoobscura, D. simulans, Delia antiqua and Culex quinquefasciatus. Additionally, they had similar secondary structure. The 3D models revealed that there are six α-helices enclosing the hydrophobic ligand binding pocket. Based on a docking study, we found that three ligands, (-)-alloaromadendrene, 2-methylnaphthalene and cyclopentadecane, had high binding affinities for TputCSP1. Moreover, the TputCSP2 protein had a higher inhibition constant with different affinities to all test ligands from host volatile substances.CONCLUSION:The two CSPs have distinct physiological functions. TputCSP1 may mediate host recognition. © 2015 Society of Chemical Industry.