Evidence for amphithallism and broad geographical hybridization potential among Agaricus subrufescens isolates from Brazil,France, and Thailand

Agaricus subrufescens is a cultivated edible and medicinal mushroom. Its known geographical distribution encompasses the Americas, Europe, Oceania, and Asia. The objective of this study was to assess mating compatibility and interfertility of strains originating from Brazil, France, and Thailand. Progeny of each strain were analyed with codominant molecular markers. Multilocus genotype tests revealed that the three strains were amphithallic with percentages of heterokaryotic single spore progenies of 75 % for the Thai strain and around 40 % for the Brazilian and French strains. In mating tests A. subrufescens had a multiallelic unifactorial system of sexual incompatibility. The three parent strains were interfertile based on experimental pairings of single-spore isolates, the recovery of hybrid heterokaryons from compatible matings, and the ability of hybrids to produce mushrooms and fertile spores. This biological approach supports the inclusion of the European strains within the species and the extension of the geographical distribution range to Asia. Our data should help to develop breeding strategies and to better manage and exploit the diversity existing in A. subrufescens.     

近红外光谱技术在食品产地溯源中的应用进展

食品产地溯源是食品安全追溯制度的重要工作。近红外光谱技术(near infrared spectroscopy,NIRS)作为一种兼具快速、简便、不破坏试样、分析过程无试剂消耗等优点的新兴绿色检测技术,近年来被逐步应用于食品产地溯源的研究中。简要介绍了应用于食品产地溯源研究中近红外光谱技术常用的化学计量学技术及软件平台,同时概述了近年来该技术在国内外食品产地溯源中的研究进展,分析了在目前产地溯源研究中的优势和存在的问题,以期为近红外光谱溯源技术的进一步发展提供参考。     

Levels of physiologically active indole derivatives in the fruiting bodies of some edible mushrooms (Basidiomycota) before and after thermal processing

Indole compounds were found in the fruiting bodies of selected mushroom species both before and after thermal processing. On the basis of HPLC analyses the following indole compounds were detected: l-tryptophan, 5-hydroxytryptophan, 5-methyltryptophan, tryptamine, 5-methyltryptamine, serotonin, indole and melatonin. The compound that was present in the largest amounts in the methanolic extracts from unprocessed mushrooms was 5-hydroxytryptophan in the amount of 7.32 mg/100 g DW in the case of the fruiting bodies of Auricularia polytricha; 15.83 in Suillus bovinus; 22.94 in Macrolepiota procera, and 24.83 in Lentinula edodes. In the methanolic extracts from thermally processed mushrooms the amount of 5-hydroxytryptophan was: 3.52 mg/100 g DW in the case of A. polytricha; 5.65 for Leccinum scabrum and 10.11 for M. procera. In addition, serotonin was found in unprocessed fruiting bodies of two mushroom species: 1.03 mg/100 g DW in L. edodes and 13.99 in L. scabrum, and also in thermally processed mushrooms.     

Productivity of agricultural residues used for the cultivation of the medicinal fungus Lentinula edodes

Lentinula edodes mushrooms were produced by solid-state fermentation, using as substrates different mixtures of wheat straw (WS), corn-cobs (CC), and oak-wood sawdust (OS). Studies were conducted for evaluating their bio-transformation efficiency with respect to substrate colonization, time of sporophore production, biological efficiency, and mushroom nitrogen content, as well as basidiocarp number and size. First, the potential of residue-substrates to support early fructification was evaluated in glass-tubes. The mushrooms appeared 50–60 days after inoculation, with WS and CC promoting earlier sporophore initiation than did OS. A second experiment, where L. edodes mushrooms were cultivated in ‘bag-logs’, revealed high productivity on CC and high mushroom protein content on OS-based substrates. However, WS appeared to promote early fructification and mushroom quality. Finally, mushroom production characteristics in tubes and bags were correlated with nitrogen content and C/N ratio of substrates. Early fructification was positively related to nitrogen content. Substrate mixtures with lower C/N ratio favoured earlier sporophore induction.     

Bioluminescence expression during the transition from mycelium to mushroom in three North American Armillaria and Desarmillaria species

Unlike most bioluminescent fungi, mycelia of Armillaria and Desarmillaria are constitutively bioluminescent while mature mushrooms are not. The absence of the luciferin, 3-hydroxyhispidin, and its precursor hispidin in mature mushrooms have been proposed to explain the lack of bioluminescence from Armillaria mushrooms. Using three North American species, A. gallica, A. mellea and D. tabescens (syn., Armillaria tabescens), we documented a decline in luminescence of ten fold during the transition from mycelia to, immature mushrooms (i.e., pins) for the two Armillaria species. As pins matured, luminescence declined by an additional two or three orders of magnitude. Lower initial luminescence of D. tabescens mycelia declined to negligible levels during mushroom development. Further, light production was localized in the gills and lower stipe of A. mellea mushrooms. The decline in luminescence during mushroom formation was reversed by addition of hispidin to stipe or gills which significantly enhanced luminescence by one and three orders of magnitude, respectively. We conclude that the modulation of Armillaria and Desarmillaria luminescence is achieved by luciferin availability early in mushroom development. However, since the temporal regulation of bioluminescence differs between Armillaria species and other genera, we conclude that bioluminescence in Armillaria is under unique selective pressures.     

Absence of induced resistance in Agaricus bisporus against Lecanicillium fungicola

Lecanicillium fungicola causes dry bubble disease and is an important problem in the cultivation of Agaricus bisporus. Little is known about the defense of mushrooms against pathogens in general and L. fungicola in particular. In plants and animals, a first attack by a pathogen often induces a systemic response that results in an acquired resistance to subsequent attacks by the same pathogen. The development of functionally similar responses in these two eukaryotic kingdoms indicates that they are important to all multi-cellular organisms. We investigated if such responses also occur in the interaction between the white button mushroom and L. fungicola. A first infection of mushrooms of the commercial A. bisporus strain Sylvan A15 by L. fungicola did not induce systemic resistance against a subsequent infection. Similar results were obtained with the A. bisporus strain MES01497, which was demonstrated to be more resistant to dry bubble disease. Apparently, fruiting bodies of A. bisporus do not express induced resistance against L. fungicola.     

The General Secretory Pathway of Burkholderia gladioli pv. agaricicola BG164R Is Necessary for Cavity Disease in White Button Mushrooms

Cavity disease in white button mushrooms is caused by Burkholderia gladioli pv. agaricicola. We describe the isolation and characterization of six mutants of the strain BG164R that no longer cause this disease on mushrooms. The mutations were mapped to genes of the general secretory pathway (GSP). This is the first report of the association of the type II secretion pathway with a disease in mushrooms. Phenotypes of the six avirulent mutants were the following: an inability to degrade mushroom tissue, a highly reduced capacity to secrete chitinase and protease, and a reduced number of flagella. Using these mutants, we also made the novel observation that the factors causing mushroom tissue degradation, thereby leading to the expression of cavity disease, can be separated from mycelium inhibition because avirulent mutants continued to inhibit the growth of actively growing mushroom mycelia. The GSP locus of B. gladioli was subsequently cloned and mapped and compared to the same locus in closely related species, establishing that the genetic organization of the gsp operon of B. gladioli pv. agaricicola is consistent with that of other species of the genus. We also identify the most common indigenous bacterial population present in the mushroom fruit bodies from a New Zealand farm, one of which, Ewingella americana, was found to be an apparent antagonist of B. gladioli pv. agaricicola. While other investigators have reported enhanced disease symptoms due to interactions between endogenous and disease-causing bacteria in other mushroom diseases, to the best of our knowledge this is the first report of an antagonistic effect.     

Diversity and abundance of macrofungi in rubber agroforests in southwestern Nigeria

The mushroom diversity was studied for 14 months in Edo State, southwestern Nigeria. A total of 76 macrofungi tantamount to 333 fruit bodies were encountered, 74% of which were identified and named. The basidiomycetes and members of the family Tricholomataceae were the best represented taxa while species on wood‐based substrates made up 66% of the total mushroom taxa. The monthly mushroom abundance profile, diversity and species richness for each sampled plot correlated with local meteorological factors, age of the sampled sites and distribution of wood‐based substrates. Jaccard, Sorensen and Bray–Curtis similarity index values showed that plots A and D, representing young actively managed and old abandoned rubber tree plantations, respectively, were the most dissimilar in mushroom composition. The hypersensitive response of macrofungal fruit bodies to climate variables qualify mushrooms as veritable biomonitors or bioindicators of climate change. This study supported earlier reports that rubber agroforests are a depauperate pool of utilitarian mushrooms.     

A new circular economy approach for integrated production of tomatoes and mushrooms

Spent mushroom Substrate is the by-product generated at the end of the mushroom growing cycle. It can be used in agriculture for different purposes, including seedling production, soil conditioning or application as an organic fertilizer. Tomato is one of the world?s most important crops, requiring considerable care, in terms of both nutrition and disease control. The objective of this study was to investigate the viability of spent mushroom substrate as a nutrient source for tomato seedlings and develop an integrated tomato and mushroom co-production system. For seedling production, different compositions were evaluated with spent mushroom substrate from Pleurotus ostreatus or substrate colonized with Agaricus bisporus. The parameters evaluated comprised germination rate, seedling quality and physicochemical analysis. A tomato and mushroom integrated production system was developed using a 40-liter pot divided into upper (spent mushroom substrate and soil), middle (spent mushroom substrate from P. ostreatus) and lower (gravel) layers. For seedlings production, plants treated with the substrate colonized with A. bisporus presented a superior root length (10.1 cm) and aerial part length (6.6 cm). Co-production of tomato and mushrooms was also shown to be viable. In this co-cultivation system between tomato and mushroom, the treatment with the substrate colonized with A. bisporus differed from others, with this treatment presenting high yields of tomato (2.35 kg/plant pot) and mushrooms (1.33 kg/plant pot) within the same bucket. With this co-production system, the tomato production time was reduced by 60 days and prolonged continuous mushroom production by 120 days. These findings show a sustainable approach to manage different agroindustrial residues, encouraging the use of these residues for olericulture and fungiculture production.     

Delignification of Wheat Straw by Pleurotus spp. under Mushroom-Growing Conditions

Pleurotus sajor-caju, P. sapidus, P. cornucopiae, and P. ostreatus mushrooms were produced on unsupplemented wheat straw. The yield of mushrooms averaged 3.6% (dry-weight basis), with an average 18% straw weight loss. Lignin losses (average, 11%) were lower than cellulose (20%) and hemicellulose (50%) losses. The cellulase digestibility of the residual straw after mushroom harvest was generally lower than that of the original straw. It does not appear feasible to simultaneously produce Pleurotus mushrooms and a highly delignified residue from wheat straw.     

Formation of flavor of dry champignons (Agaricus bisporus L.)

The composition of aroma compounds of dry champignons (Agaricus bisporus L.) were identified using capillary gas chromatography and chromatography-mass spectrometry. In total, 56 compounds were identified. It was found that the flavor of dry mushrooms was formed by the volatile compounds produced as a result of enzymatic and oxidative conversion of unsaturated fatty acids as well as in the Maillard reaction. Unsaturated alcohols and ketones containing eight carbon atoms determined the mushroom note of the product. The specific aroma of dry mushrooms was determined by a complex composition of substituted sul- fur-, oxygen-, and nitrogen-containing heterocyclic compounds as well as by aliphatic carbonyl compounds and methional. It was found that the concentrations of volatile carbonylic and heterocyclic compounds increased after the addition of a mixture of amino acids to mushrooms before drying. As a result, the intensity of the aroma of dry mushrooms increased.     

基于Maxent模型的未来气候变化情景下胡杨在中国的潜在地理分布

胡杨(Populus euphratica)是全世界干旱和半干旱区急需优先保护的林木基因资源,预测未来气候变化情景下胡杨在中国的潜在地理分布将为胡杨种群资源的保护和管理提供科学依据,并为绿洲恢复过程中胡杨的合理种植和配置提供有价值的理论指导。本研究基于胡杨在中国地区的92条有效分布记录和10个环境因子变量,利用Maxent模型和ArcGIS软件预测了未来气候变化情景下胡杨在中国的潜在地理分布,综合环境因子变量贡献率及置换重要值、刀切法检验评估制约现代胡杨潜在地理分布的重要因子,采用响应曲线确定环境因子变量的适宜区间,定量确定胡杨未来受威胁的潜在地理分布区域和面积。结果表明：（1）Maxent模型的预测准确度极高,受试者工作曲线面积（AUC值）达0.932,现代胡杨潜在地理分布的总适生区面积为289.94×104km2,主要位于内蒙古中西部地区（额济纳旗和阿拉善地区）、新疆大部分地区、甘肃北部和西北部地区、青海中西部地区和宁夏北部地区;（2）影响胡杨的潜在地理分布的主要环境因子变量为气温因子变量（年均温和最冷月最低温）和降水因子变量（最湿月降水量和最干季降水量）,最湿月降水量是影响胡杨潜在地理分布的关键因素;（3）在未来4种气候变化情景下,胡杨不同等级潜在地理分布区的面积较现代潜在地理分布区面积均有不同程度的缩小,且整体上看胡杨的潜在地理分布区有向高海拔区域迁移的趋势。     

Plantago asiatica groundcover supports Amblyseius tsugawai (Acari: Phytoseiidae) populations in apple orchards

Amblyseius tsugawai Ehara (Acari: Phytoseiidae) is a major predator of spider mites in orchards in Japan. To support populations in apple orchards in Akita Prefecture, northern Japan, we investigated whether it can use Plantago asiatica L. as a food resource. In laboratory tests, survival did not differ significantly between female adults given water only and those given a piece of P. asiatica leaf and water. However, A. tsugawai reproduces by feeding on P. asiatica pollen, and significantly more mites were reared on P. asiatica pollen than on tea pollen, which is commonly used for rearing phytoseiid mites. In orchards in 2013, female adults were observed on leaves of P. asiatica from late May; numbers peaked in mid-June and gradually decreased until late July. Most adults were found along veins on the hidden sides of the leaves. Female adults were also collected in Phyto traps attached to plants between late May and early August. Pollen production of P. asiatica peaked from mid-June to early July, when numbers of adults peaked on the plants. These results suggest that conservation of P. asiatica in apple orchards would sustain A. tsugawai populations.     

Systematic Evaluation of Isoëtes asiatica Makino (Isoëtaceae) based on AFLP, nrITS, and Chloroplast DNA Sequences

On the basis of amplified fragment length polymorphism (AFLP) and nucleotide sequence data from nuclear ribosomal internal transcribed spacer (nrITS) and three chloroplast DNA regions (rbcL, cpITS, and trnS-psbC spacer), we investigated the species delimitation and the evolutionary lineage of Isoëtes asiatica from Hokkaido, Japan. The neighbor-joining (NJ) dendrogram based on AFLP markers revealed the well-defined clusters (bootstrap value?=?100%) of I. asiatica. Results from the principal component analysis are largely congruent with those obtained in the NJ dendrogram. The maximum parsimony analysis, based on data from nrITS and three chloroplast DNA sequences, supported a monophyly of three species, I. asiatica, Isoëtes echinospora, and Isoëtes maritima from Hokkaido, Kamchatka, and Alaska regions. The distinct species status of I. asiatica was also well supported in the combined chloroplast DNA phylogeny. Therefore, I. asiatica appear to represent example of gradual speciation due to spatial isolation of ancestral populations followed by genetic divergence. Our results also suggest that I. asiatica is probably not the ancestral diploid of the polyploids occurring in East Asia.     

Agaricus subrufescens: A review

Medicinal mushrooms have currently become a hot issue due to their various therapeutic properties. Of these, Agaricus subrufescens, also known as the “almond mushroom”, has long been valued by many societies (i.e., Brazil, China, France, and USA). Since its discovery in 1893, this mushroom has been cultivated throughout the world, especially in Brazil where several strains of A. subrufescens have been developed and used as health food and alternative medicine. This article presents up-to-date information on this mushroom including its taxonomy and health promoting benefits. Medicinal properties of A. subrufescens are emphasized in several studies which are reviewed here. In addition, safety issues concerning the use of this fungus will be discussed.