Encapsulation of Ammoides pusila Essential Oil into Mesoporous Silica Particles for the Enhancement of Their Activity against Fusarium avenaceum and Its Enniatins Production.

Essential oils (EOs) that have antifungal activity and mycotoxin reduction ability are candidates to develop bioactive alternatives and environmentally friendly treatment against Fusarium species in cereals. However, their practical use is facing limitations such as high volatility, UV sensitivity, and fast oxidation. Encapsulation techniques are supposed to provide protection to the EOs and control their release into the environment. Ammoides pusilla essential oil (AP-EO) proved to be an efficient inhibitor of Fusarium avenaceum growth and its enniatins (ENNs) production. In the present work, AP-EO was encapsulated, using the impregnation method, into mesoporous silica particles (MSPs) with narrow slit pores (average diameter = 3.1 nm) and coated with chitosan. In contact assays using an agar medium, the antifungal activity of AP-EO at 0.1 µL mL-1 improved by three times when encapsulated into MSPs without chitosan and the ENNs production was significantly inhibited both in coated and non-coated MSPs. Controls of MSPs also inhibited the ENNs production without affecting the mycelial growth. In fumigation experiments assessing the activity of the EO volatile compounds, encapsulation into MSPs improved significantly both the antifungal activity and ENNs inhibition. Moreover, coating with chitosan stopped the release of EO. Thus, encapsulation of an EO into MSPs improving its antifungal and antimycotoxin properties is a promising tool for the formulation of a natural fungicide that could be used in the agriculture or food industry to protect plant or food products from the contamination by toxigenic fungi such as Fusarium sp. and their potential mycotoxins.

Ammoides pusilla Essential Oil: A Potent Inhibitor of the Growth of Fusarium avenaceum and Its Enniatin Production.

Enniatins are mycotoxins produced by Fusarium species contaminating cereals and various agricultural commodities. The co-occurrence of these mycotoxins in large quantities with other mycotoxins such as trichothecenes and the possible synergies in toxicity could lead to serious food safety problems. Using the agar dilution method, Ammoides pusilla was selected among eight Tunisian plants for the antifungal potential of its essential oil (EO) on Fusarium avenaceum mycelial growth and its production of enniatins. Two EO batches were produced and analyzed by GC/MS-MS. Their activities were measured using both contact assays and fumigant tests (estimated IC50 were 0.1 µL·mL-1 and 7.6 µL·L-1, respectively). The A. pusilla EOs and their volatiles inhibited the germination of spores and the mycelial growth, showing a fungistatic but not fungicidal activity. The accumulation of enniatins was also significantly reduced (estimated IC50 were 0.05 µL·mL-1 for the contact assays and 4.2 µL·L-1 for the fumigation assays). The most active batch of EO was richer in thymol, the main volatile compound found. Thymol used as fumigant showed a potent fungistatic activity but not a significant antimycotoxigenic activity. Overall, our data demonstrated the bioactivity of A. pusilla EO and its high potential to control F. avenaceum and its enniatins production in agricultural commodities.

Evolution of Fusarium tricinctum and Fusarium avenaceum mitochondrial genomes is driven by mobility of introns and of a new type of palindromic microsatellite repeats.

BACKGROUND: Increased contamination of European and Asian wheat and barley crops with "emerging" mycotoxins such as enniatins or beauvericin, produced by Fusarium avenaceum and Fusarium tricinctum, suggest that these phylogenetically close species could be involved in future food-safety crises. RESULTS: The mitochondrial genomes of F. tricinctum strain INRA104 and F. avenaceum strain FaLH27 have been annotated. A comparative analysis was carried out then extended to a set of 25 wild strains. Results show that they constitute two distinct species, easily distinguished by their mitochondrial sequences. The mitochondrial genetic variability is mainly located within the intergenic regions. Marks of variations show they have evolved (i) by Single Nucleotide Polymorphisms (SNPs), (ii) by length variations mediated by insertion/deletion sequences (Indels), and (iii) by length mutations generated by DNA sliding events occurring in mononucleotide (A)n or (T)n microsatellite type sequences arranged in a peculiar palindromic organization. The optionality of these palindromes between both species argues for their mobility. The presence of Indels and SNPs in palindrome neighbouring regions suggests their involvement in these observed variations. Moreover, the intraspecific and interspecific variations in the presence/absence of group I introns suggest a high mobility, resulting from several events of gain and loss during short evolution periods. Phylogenetic analyses of intron orthologous sequences suggest that most introns could have originated from lateral transfers from phylogenetically close or distant species belonging to various Ascomycota genera and even to the Basidiomycota fungal division. CONCLUSIONS: Mitochondrial genome evolution between F. tricinctum and F. avenaceum is mostly driven by two types of mobile genetic elements, implicated in genome polymorphism. The first one is represented by group I introns. Indeed, both genomes harbour optional (inter- or intra-specifically) group I introns, all carrying putatively functional hegs, arguing for a high mobility of these introns during short evolution periods. The gain events were shown to involve, for most of them, lateral transfers between phylogenetically distant species. This study has also revealed a new type of mobile genetic element constituted by a palindromic arrangement of (A) n and (T) n microsatellite sequences whose presence was related to occurrence of SNPs and Indels in the neighbouring regions.

Priming to protect maize from Fusarium verticillioides and its fumonisin accumulation.

BACKGROUND: Systemic infection through the seed is one of the routes used by the mycotoxinogenic pathogen Fusarium verticillioides for colonizing maize plants. The prohibition of the use of most chemical fungicides by the EU has promoted research on plant resistance inducers as an effective and sustainable alternative. Induction of a priming state in maize seeds might affect their susceptibility to contamination and accumulation of fumonisins. This state by application of a natural fertilizer called Chamae on maize seeds, was investigated in two varieties to control the colonization by the fungus and the accumulation of fumonisins B1 , B2 and B3 , germinating seeds, dead plants and yield. RESULTS: After inoculation of F. verticillioides on germinating seeds, the colonization by the fungus and the accumulation of fumonisins were significantly lower in seedlings coming from treated seeds, but a significant number of plants stopped their development by necrosis. In a field trial, the 0.01% (v/v) application dilution showed a lower plant density, although the level of biomass at harvest was not affected. CONCLUSION: The priming state contributed to the control of F. verticillioides development from seed infection and fumonisin accumulation in the early stage of plant growth, without affecting the final crop yield, and could reduce fungicide use and environmental contamination. © 2018 Society of Chemical Industry.

Yeast and bacteria from ensiled high moisture maize grains as potential mitigation agents of fumonisin B1.

BACKGROUND: Fumonisin B1 (FB1 ) is a mycotoxin produced by several Fusarium species and is a very common contaminant of maize-based food and feed throughout the world. The selection and use of FB1 -degrading microorganisms appears as a promising alternative to cope with the problem of toxicity towards humans and livestock. High moisture maize grain silage, which is based on natural maize fermentation, could be an interesting reservoir of such microorganisms. RESULTS: Using an in vitro simulated silage model with FB1 naturally contaminated grains, we demonstrated a significant raw decrease in FB1 during ensiling process ascribed to biodegradation mechanisms. A panel of 98 bacteria and yeasts were isolated from this matrix and selected for their ability to use FB1 as the sole source of C and N. For nine of them, the ability to degrade FB1 in vitro was evidenced. Notably, two bacteria identified as Lactobacillus sp. were highlighted for their efficient FB1 -degrading capacity and production of hydrolysed FB1 as intermediate degradation metabolite. CONCLUSION: Fermentation of high moisture maize grain contaminated with FB1 leads to a significant reduction of the toxin and allows the isolation of FB1 -degrading microorganisms that could further be used as FB1 decontaminating agents. © 2016 Society of Chemical Industry.

Spore behaviors reveal a category of mating-competent infertile heterokaryons in the offspring of the medicinal fungus Agaricus subrufescens.

Strain breeding is much less advanced in the edible and medicinal species Agaricus subrufescens than in Agaricus bisporus, the button mushroom. Both species have a unifactorial system of sexual incompatibility, a mating type locus tightly linked to a centromere, and basidia producing both homokaryotic (n) and heterokaryotic (n + n) spores. In A. bisporus, breeding is mainly based on direct selection among the heterokaryotic offspring and on hybridization between homokaryotic offspring. The parental heterozygosity is highly maintained in the heterokaryotic offspring due to suppression of recombination and preferential pairing in the spores of nuclei, each one per second meiotic divisions; such "non-sister nuclei" heterokaryons are fertile. In A. subrufescens, recent studies revealed that recombination is not suppressed and that nuclei from the same second meiotic division can also be paired in a spore that give rise to a "sister nuclei" heterokaryon in which the nuclei bear the same mating type allele. The objective of the present work was to investigate the potential function of the different categories of spores in A. subrufescens and their possible use in a genetic breeding program. Using eight co-dominant molecular markers, we found that half of the offspring of the A. subrufescens strain WC837 were heterokaryotic, one quarter of them being sister nuclei heterokaryons. These heterokaryons were infertile and behaved like homokaryons, being even able to cross between each other. In contrast, non-sister nuclei heterokaryons could fruit but inconsistently due to inbreeding depression. Potential roles of these two categories of heterokaryons in nature and consequences for strain breeding are discussed.

The intraspecific variability of mitochondrial genes of Agaricus bisporus reveals an extensive group I intron mobility combined with low nucleotide substitution rates.

Intraspecific mitochondrial variability was studied in ten strains of A. bisporus var. bisporus, in a strain representative of A. bisporus var. eurotetrasporus and in a strain of the closely related species Agaricus devoniensis. In A. bisporus, the cox1 gene is the richest in group I introns harboring homing endonuclease genes (heg). This study led to identify group I introns as the main source of cox1 gene polymorphism. Among the studied introns, two groups were distinguished according to the heg they contained. One group harbored heg maintained putatively functional. The other group was composed of eroded heg sequences that appeared to evolve toward their elimination. Low nucleotide substitution rates were found in both types of intronic sequences. This feature was also shared by all types of studied mitochondrial sequences, not only intronic but also genic and intergenic ones, when compared with nuclear sequences. Hence, the intraspecific evolution of A. bisporus mitochondrial genome appears characterized by both an important mobility (presence/absence) of large group I introns and by low nt substitution rates. This stringent conservation of mitochondrial sequences, when compared with their nuclear counterparts, appears irrespective of their apparent functionality and contrasts to what is widely accepted in fungal sequence evolution. This strengthens the usefulness of mtDNA sequences to get clues on intraspecific evolution.

Deciphering the ability of Agaricus bisporus var. burnettii to produce mushrooms at high temperature (25 °C).

The button mushroom Agaricus bisporus is cultivated almost worldwide. Its cultivation is standardized and a temperature of 16-19 °C is needed during the fruiting period. The development of A. bisporus cultivars able to fruit at higher temperature (FHT) represents a promising alternative to reduce energy costs during cultivation in hot countries as well as in temperate countries during the hot season. A. bisporus var. burnettii is able to fruit at 25 °C. Understanding the biological mechanisms that underlie such a thermo-tolerance is a prerequisite to further development of breeding strains. The foundation of the FHT ability of the var. burnettii was dissected using a combination of candidate gene approaches and genetic tools. Transcript profiling of A. bisporus var. burnettii at two developmental stages (primordium P and sporophore SP) under two fruit-producing temperature conditions (17 °C and 25 °C) were established by cDNA-AFLP. The expression patterns were more similar within the same stage at the two different temperatures rather than between stages under the same temperature. Only one transcript-derived fragment (TDF) sequence differentially expressed between temperatures was recovered but it could not be further characterized. Twenty-nine TDF sequences differentially expressed between development stages were obtained. The phenotypic assessment of an intervarietal A. bisporus var. bisporus×A. bisporus var. burnettii progeny demonstrated the complex inheritance of the FHT trait. Two quantitative trait loci (QTL) involved in the number of fruit bodies yielded at 25 °C were found on LG II and LG VI. Two functional candidate genes known to be potentially involved in A. bisporus thermo-tolerance, a heat shock protein (HSP70) gene and a gene coding for a para-aminobenzoic acid synthase (PABA), were found in the vicinity of the QTL on LG II. Several positional candidate genes have been also identified in the confidence interval of the QTL on LG VI and are promising for further fine mapping purpose.

The first set of expressed sequence tags (EST) from the medicinal mushroom Agaricus subrufescens delivers resource for gene discovery and marker development.

Agaricus subrufescens is one of the most important culinary-medicinal cultivable mushrooms with potentially high-added-value products and extended agronomical valorization. The development of A. subrufescens-related technologies is hampered by, among others, the lack of suitable molecular tools. Thus, this mushroom is considered as a genomic orphan species with a very limited number of available molecular markers or sequences. To fill this gap, this study reports the generation and analysis of the first set of expressed sequence tags (EST) for A. subrufescens. cDNA fragments obtained from young sporophores (SP) and vegetative mycelium in liquid culture (CL) were sequenced using 454 pyrosequencing technology. After assembly process, 4,989 and 5,125 sequences were obtained in SP and CL libraries, respectively. About 87% of the EST had significant similarity with Agaricus bisporus-predicted proteins, and 79% correspond to known proteins. Functional categorization according to Gene Ontology could be assigned to 49% of the sequences. Some gene families potentially involved in bioactive compound biosynthesis could be identified. A total of 232 simple sequence repeats (SSRs) were identified, and a set of 40 EST-SSR polymorphic markers were successfully developed. This EST dataset provides a new resource for gene discovery and molecular marker development. It constitutes a solid basis for further genetic and genomic studies in A. subrufescens.

Optimization of the cultivation conditions for mushroom production with European wild strains of Agaricus subrufescens and Brazilian cultivars.

BACKGROUND: The almond mushroom Agaricus subrufescens (formerly Agaricus blazei or Agaricus brasiliensis) is cultivated at commercial level in Brazil and some Asian countries on local substrates and casing mixtures. Despite its tropical origin, A. subrufescens might be a seasonal option for mushroom growers in western countries, where some wild strains have been isolated. For this purpose, cultivation conditions were developed starting from the substrate and casing mixture commonly used for commercial production of the button mushroom Agaricus bisporus in France. RESULTS: The commercial compost, based on wheat straw and horse manure, used for A. bisporus and the casing mixture (peat and limestone) supplemented with fine sand proved efficient to grow A. subrufescens. Increasing the depth of the casing layer improved significantly the yield and time to fruiting. Daily variations in temperature did not markedly modify the yield. Significantly higher mushroom biomass was obtained with three wild European strains compared with three Brazilian cultivars. The very productive wild strain CA438-A gave mushrooms of size and dry matter content comparable to those of a cultivar. CONCLUSION: Commercial production of A. subrufescens can be developed in western countries on the wheat straw-based substrate commonly used for A. bisporus in these regions, by a simple modification of the casing mixture and maintaining the incubation temperature throughout the crop, which is expected to save energy during summer. Good yields were obtained cultivating European strains under optimised parameters.

Potential of European wild strains of Agaricus subrufescens for productivity and quality on wheat straw based compost.

The Brazilian almond mushroom is currently cultivated for its medicinal properties but cultivars are suspected all to have a common origin. The objective of this work was to assess the potential of wild isolates of Agaricus subrufescens Peck (Agaricus blazei, Agaricus brasiliensis) as a source of new traits to improve the mushroom yield and quality for developing new cultures under European growing conditions. The wild European strains analysed showed a good ability to be commercially cultivated on wheat straw and horse manure based compost: shorter time to fruiting, higher yield, similar antioxidant activities when compared to cultivars. They have a valuable potential of genetic and phenotypic diversity and proved to be interfertile with the original culture of the Brazilian almond mushroom. Intercontinental hybrids could be obtained and combine properties from both Brazilian and European germplasm for increasing the choice of strains cultivated by the mushroom growers.

Relationship between yield components and partial resistance to Lecanicillium fungicola in the button mushroom, Agaricus bisporus, assessed by quantitative trait locus mapping.

Dry bubble, caused by Lecanicillium fungicola, is one of the most detrimental diseases affecting button mushroom cultivation. In a previous study, we demonstrated that breeding for resistance to this pathogen is quite challenging due to its quantitative inheritance. A second-generation hybrid progeny derived from an intervarietal cross between a wild strain and a commercial cultivar was characterized for L. fungicola resistance under artificial inoculation in three independent experiments. Analysis of quantitative trait loci (QTL) was used to determine the locations, numbers, and effects of genomic regions associated with dry-bubble resistance. Four traits related to resistance were analyzed. Two to four QTL were detected per trait, depending on the experiment. Two genomic regions, on linkage group X (LGX) and LGVIII, were consistently detected in the three experiments. The genomic region on LGX was detected for three of the four variables studied. The total phenotypic variance accounted for by all QTL ranged from 19.3% to 42.1% over all traits in all experiments. For most of the QTL, the favorable allele for resistance came from the wild parent, but for some QTL, the allele that contributed to a higher level of resistance was carried by the cultivar. Comparative mapping with QTL for yield-related traits revealed five colocations between resistance and yield component loci, suggesting that the resistance results from both genetic factors and fitness expression. The consequences for mushroom breeding programs are discussed.

Quantitative trait locus mapping of yield-related components and oligogenic control of the cap color of the button mushroom, Agaricus bisporus.

As in other crops, yield is an important trait to be selected for in edible mushrooms, but its inheritance is poorly understood. Therefore, we have investigated the complex genetic architecture of yield-related traits in Agaricus bisporus through the mapping of quantitative trait loci (QTL), using second-generation hybrid progeny derived from a cross between a wild strain and a commercial cultivar. Yield, average weight per mushroom, number of fruiting bodies per m(2), earliness, and cap color were evaluated in two independent experiments. A total of 23 QTL were detected for 7 yield-related traits. These QTL together explained between 21% (two-flushes yield) and 59% (earliness) of the phenotypic variation. Fifteen QTL (65%) were consistent between the two experiments. Four regions underlying significant QTL controlling yield, average weight, and number were detected on linkage groups II, III, IV, and X, suggesting a pleiotropic effect or tight linkage. Up to six QTL were identified for earliness. The PPC1 locus, together with two additional genomic regions, explained up to 90% of the phenotypic variation of the cap color. Alleles from the wild parent showed beneficial effects for some yield traits, suggesting that the wild germ plasm is a valuable source of variation for several agronomic traits. Our results constitute a key step toward marker-assisted selection and provide a solid foundation to go further into the biological mechanisms controlling productive traits in the button mushroom.

Experimental Outcrossing in Agaricus bisporus Revealed a Major and Unexpected Involvement of Airborne Mycelium Fragments.

Agaricus bisporus var. bisporus, the button mushroom, has a predominantly pseudohomothallic life cycle. Most of its spores are heterokaryotic and give rise to fertile heterokaryons. However, previous studies have suggested that outcrossing should not be rare in wild populations. In order to discover how outcrossing occurs, we experimentally favored it between aerial propagules of a fruiting donor mycelium and a delayed receiver mycelium that only invaded culture trays. Two donor/receiver pairs were studied, and potentially hybrid basidiomata collected on the receiver trays were analyzed with a mitochondrial marker, two unlinked nuclear CAPS markers, then haplotype markers based on DNA sequences obtained after PCR cloning of the rDNA ITS region and the fruk gene. For one of the two pairs, most basidiomata were hybrids between the donor and the receiver. Genotyping of the hybrids revealed only two genotypes consistent with outcrossing involving airborne mycelium fragments rather than basidiospores. The resident receiver heterokaryon that provided its mitochondria to the hybrid basidiomata is suspected to have had a trophic contribution to their growth and successful fruiting. The high level of heterozygosity and the cultivar introgression previously revealed in wild populations of this pseudohomothallic species may result from outcrossing involving airborne pieces of mycelium.

Characterization of Fusarium acuminatum: A Potential Enniatins Producer in Tunisian Wheat.

Fusarium Head Blight (FHB), caused by multiple species of Fusarium in small grain cereals, is a significant and long-standing problem anywhere in the world. Knowing regional Fusarium spp. present on non-symptomatic grains and their potential for mycotoxin production is of concern for identifying novel actions for FHB and mycotoxin management, such as treatments with essential oils. Analyzing the mycotoxin content of grains from non-symptomatic ears of different wheat varieties cultivated in Tunisia, we isolated Fusaria specimens identified as F. culmorum and F. acuminatum using analysis of the partial DNA sequence of the ß-tubulin gene and ITS region. Two isolates of the latter species, uncommon in cereal grains in this region until now, were shown to be effective producers of enniatins in vitro, with 1390 and 3089 µg g-1 mycelial biomass (dry) in 11-day-old cultures. The susceptibility of an isolate of F. acuminatum to the fungistatic and antimycotoxin effects of eight essential oils was measured. Essential oils from Ammoides pusilla and Thymus capitatus used at 0.1 µL mL-1 in an agar culture medium, affected the mycelial growth by 55% and 79%, respectively and reduced the accumulation of enniatins per unit of mycelial colony by 26% and 52%, respectively. Finally, F. acuminatum was shown to be a contaminant of wheat grains in Tunisia and it may contribute to the contamination in enniatins. Two essential oils of Tunisian plants could be used for developing a biofungicide limiting both its mycelial growth and its accumulation of mycotoxins in grains.

Comparative linkage mapping in the white button mushroom Agaricus bisporus provides foundation for breeding management.

To assess the feasibility of marker-assisted selection in mushrooms, a comparative mapping study between two connected populations of the white button mushroom Agaricus bisporus was performed. The first mapping population had been used already for the construction of the A. bisporus reference linkage map. In the present study, a new linkage map based on the segregation analysis of a second generation hybrid progeny was developed. In order to increase the number of available anchor markers, we developed a conversion procedure of an amplified fragment length polymorphism (AFLP) fragment into sequence-specific PCR marker. Seventeen AFLP-converted markers (ACM) were then used for mapping purpose, among which 14 were common to the two maps. The linkage map presented herein consists of 183 markers (53 cleaved amplified polymorphic sequence, 16 SSR, 17 ACM, 96 AFLP and PPC1 locus), distributed among 13 linkage groups (LG), and covering 851 cM. Thanks to 84 common markers, we have stated that marker order was well conserved, except for LG I; significant unequal recombination rates occurred over the whole genome; regions with markers showing skewed segregation patterns differed between the two maps. Our results suggested a strong impact of the genetic background on recombination ability. Consequences for mushroom breeding are discussed. These maps will facilitate further comparative mapping studies of quantitative trait locus detection.

Production of edible mushrooms in forests: trends in development of a mycosilviculture.

Developing the production of ectomycorrhizal (ECM) mushrooms in forest has become a challenge. Only a few ECM species are currently cultivable. Controlled mycorrhization practices offer promising advance to produce currently uncultivable ECM mushrooms. The persistence of the production of edible species, either cultivated or wild, depends on both the tree and the ecological environment (fungal communities, climate, soil, tree development). Developing adapted forest management practices appears to be means to improve production of edible ECM mushrooms. This review summarises current knowledge on the development of a science-based mycosilviculture for the production of edible ECM mushrooms.

The medicinal Agaricus mushroom cultivated in Brazil: biology, cultivation and non-medicinal valorisation.

Sun mushroom is a cultivated mushroom extensively studied for its medicinal properties for several years and literature abounds on the topic. Besides, agronomical aspects were investigated in Brazil, the country the mushroom comes from, and some studies focus on the biology of the fungus. This review aimed to present an overview of the non-medicinal knowledge on the mushroom. Areas of commercial production and marketing trends are presented. Its specific fragrance, taste, nutritional value and potential use of extracts as food additives are compared to those of the most cultivated fungi and laboratory models. The interest of the mushroom for lignocellulosic enzyme production and source of biomolecules for the control of plant pathogens are shown. Investigation of genetic variability among cultivars is reported. Growing and storage of mycelium, as well as cultivation conditions (substrate and casing generally based on local products; indoor and outdoor cultivation; diseases and disorders) are described and compared to knowledge on Agaricus bisporus.

An expanded genetic linkage map of an intervarietal Agaricus bisporus var. bisporusxA. bisporus var. burnettii hybrid based on AFLP, SSR and CAPS markers sheds light on the recombination behaviour of the species.

A genetic linkage map for the edible basidiomycete Agaricus bisporus was constructed from 118 haploid homokaryons derived from an intervarietal A. bisporus var. bisporus x A. bisporus var. burnettii hybrid. Two hundred and thirty-one AFLP, 21 SSR, 68 CAPS markers together with the MAT, BSN, PPC1 loci and one allozyme locus (ADH) were evenly spread over 13 linkage groups corresponding to the chromosomes of A. bisporus. The map covers 1156cM, with an average marker spacing of 3.9cM and encompasses nearly the whole genome. The average number of crossovers per chromosome per individual is 0.86. Normal recombination over the entire genome occurs in the heterothallic variety, burnettii, contrary to the homothallic variety, bisporus, which showed adaptive genome-wide suppressed recombination. This first comprehensive genetic linkage map for A. bisporus provides foundations for quantitative trait analyses and breeding programme monitoring, as well as genome organisation studies.

Microbially induced diseases of Agaricus bisporus: biochemical mechanisms and impact on commercial mushroom production.

The button mushroom, Agaricus bisporus (Lange) Imbach, the most common cultivated mushroom, is susceptible to a wide range of virus, bacterial, and fungal diseases. However, only some diseases were studied for the mechanisms involved in the host-microorganism interaction. This review deals with biochemical mechanisms related to cavity disease (Burkholderia gladioli) and to the interaction between A. bisporus and the causal agents responsible for the most severe diseases, namely the bacteria Pseudomonas tolaasii and Pseudomonas reactans and the fungi Trichoderma aggressivum and Lecanicillium fungicola.