Characterization and overexpression of RHO1 from Cryptococcus laurentii ZJU10 activates CWI signaling pathway on enhancing the inhibition of blue mold on pears

Mycotoxins in Cheese: Assessing Risks, Fungal Contaminants, and Control Strategies for Food Safety

According to the scientific information reviewed, cheese is highly susceptible to contamination by mycotoxin-producing fungi, primarily species from the genera Aspergillus (A. niger, A. flavus) and Penicillium (P. commune, P. solitum, P. palitans, and P. crustosum). Studies on various types of cheese made from cow's milk report an average concentration of Aflatoxin M1 (AFM1) at 13,000 ng kg-1, which is alarming since the regulatory limits for AFM1 in cheese range from 250 to 500 ng kg-1. For instance, limits set by Codex Alimentarius, the European Commission (EC), Turkey, and Iran are 250 ng kg-1. In the Netherlands, the limit is 200 ng kg-1, and in Italy, it is 450 ng kg-1. However, the concentration of mycotoxins frequently exceeds these regulatory limits, including critical mycotoxins such as ochratoxin A, citrinin, and cyclopiazonic acid, which pose significant global health concerns. Therefore, this study aims to review the mycobiota responsible for producing key mycotoxins in cheese and to assess the influence of physicochemical factors on fungal growth and mycotoxin production. By incorporating control strategies such as hygiene practices, pasteurization, and the use of preservatives, this study seeks to improve methodologies in the cheese production chain and mitigate contamination by fungi and mycotoxins.

Integrated Transcriptomic and Proteomic Analyses Reveal Molecular Mechanism of Response to Heat Shock in Morchella sextelata

Morels (Morchella spp.), as one of the rare macroascomycetes that can be cultivated artificially, possess significant economic and scientific values. Morel cultivation is highly sensitive to elevated temperatures; however, the mechanisms of their response to heat shock remain poorly understood. This study integrated transcriptomic and quantitative proteomic analyses of two M. sextelata strains with different thermotolerance (labeled as strains C and D) under normal (18 °C) and high temperature (28 °C) conditions. From over 9300 transcripts and 5000 proteins, both consistency and heterogeneity were found in response to heat shock between the two strains. Both strains displayed a capacity to maintain cellular homeostasis in response to heat shock through highly expressed cell wall integrity (CWI) pathways, heat shock proteins (HSPs), and antioxidant systems. However, strain D, which exhibited stronger thermotolerance, specifically upregulated the ubiquitin ligase Rsp5, thereby further promoting the expression of HSPs, which may be a key factor influencing the thermotolerance difference among M. sextelata strains. A conceptual model of the heat shock adaptation regulatory network in M. sextelata was proposed for the first time; the results provide novel insights into the thermotolerance response mechanisms of macroascomycetes and valuable resources for the breeding enhancement of thermotolerant morel strains.

Recent advances in research on biocontrol of postharvest fungal decay in apples

Apple is the largest fruit crop produced in temperate regions and is a popular fruit worldwide. It is, however, susceptible to a variety of postharvest fungal pathogens, including Penicillium expansum, Botrytis cinerea, Botryosphaeria dothidea, Monilia spp., and Alternaria spp. Decays resulting from fungal infections severely reduce apple quality and marketable yield. Biological control utilizing bacterial and fungal antagonists is an eco-friendly and effective method of managing postharvest decay in horticultural crops. In the current review, research on the pathogenesis of major decay fungi and isolation of antagonists used to manage postharvest decay in apple is presented. The mode of action of postharvest biocontrol agents (BCAs), including recent molecular and genomic studies, is also discussed. Recent research on the apple microbiome and its relationship to disease management is highlighted, and the use of additives and physical treatments to enhance biocontrol efficacy of BCAs is reviewed. Biological control is a critical component of an integrated management system for the sustainable approaches to apple production. Additional research will be required to explore the feasibility of developing beneficial microbial consortia and novel antimicrobial compounds derived from BCAs for postharvest disease management, as well as genetic approaches, such as the use of CRISPR/Cas9 technology.

The role of Rho1 gene in the cell wall integrity and polysaccharides biosynthesis of the edible mushroom Grifola frondosa

Grifola frondosa polysaccharides, especially β-glucans, showed the significant antitumor, hypoglycemic, and immune-stimulating activities. In the present study, a predominant regulatory subunit gfRho1p of β-1,3-glucan synthase in G. frondosa was identified with a molecular weight of 20.79 kDa and coded by a putative 648-bp small GTPase gene gfRho1. By constructing mutants of RNA interference and over-expression gfRho1, the roles of gfRho1 in the growth, cell wall integrity and polysaccharide biosynthesis were well investigated. The results revealed that defects of gfRho1 slowed mycelial growth rate by 22% to 33%, reduced mycelial polysaccharide and exo-polysaccharide yields by 4% to 7%, increased sensitivity to cell wall stress, and down-regulated gene transcriptions related to PKC-MAPK signaling pathway in cell wall integrity. Over-expression of gfRho1 improved mycelial growth rate and polysaccharide production of G. frondosa. Our study supports that gfRho1 is an essential regulator for polysaccharide biosynthesis, cell growth, cell wall integrity and stress response in G. frondosa.

Protein Expression Profile and Transcriptome Characterization of Penicillium expansum Induced by Meyerozyma guilliermondii

Antagonistic yeasts can inhibit fungal growth. In our previous research, Meyerozyma guilliermondii, one of the antagonistic yeasts, exhibited antagonistic activity against Penicillium expansum. However, the mechanisms, especially the molecular mechanisms of inhibiting activity of M. guilliermondii, are not clear. In this study, the protein expression profile and transcriptome characterization of P. expansum induced by M. guilliermondii were investigated. In P. expansum induced by M. guilliermondii, 66 proteins were identified as differentially expressed, among them six proteins were upregulated and 60 proteins were downregulated, which were associated with oxidative phosphorylation, ATP synthesis, basal metabolism, and response regulation. Simultaneously, a transcriptomic approach based on RNA-Seq was applied to annotate the genome of P. expansum and then studied the changes of gene expression in P. expansum treated with M. guilliermondii. The results showed that differentially expressed genes such as HEAT, Phosphoesterase, Polyketide synthase, ATPase, and Ras-association were significantly downregulated, in contrast to Cytochromes P450, Phosphatidate cytidylyltransferase, and Glutathione S-transferase, which were significantly upregulated. Interestingly, the downregulated differentially expressed proteins and genes have a corresponding relationship; these results revealed that these proteins and genes were important in the growth of P. expansum treated with M. guilliermondii.