Bioconversion of agrowastes by Lentinula edodes: the high potential of viticulture residues

Valorization of agro-forest wastes (oak acorns, vineyard pruning, and olive pruning) through the cultivation of shiitake (Lentinula edodes) mushrooms

Experimental research has been focusing on developing new substrates for growing shiitake mushrooms as alternatives to the standard oak sawdust substrate. The selection of appropriate lignocellulosic materials is based on their availability in the production area and their compatibility with the requirements of the mushroom species being cultivated. In comparison to oak sawdust substrate (OS) as the control, this study evaluated the potential of oak acorns (OA), olive pruning (OLPR), and vineyard pruning (VIP), and various combinations: OA-OLPR:1-1, OA-VIP:1-1, OS-OLPR:1-1, and OS-VIP:1-1, prepared on a dry weight basis. In comparison to OS, complete mycelial development was hastened in OA, OA-VIP: 1-1, and OS-VIP:1-1 by 9.5, 7.9, and 4.2 days and delayed in OLPR and OS-OLPR:1-1 by 11.3 and 7.0 days, respectively. Also, harvest was earlier in OA, OA-VIP:1-1, and OS-VIP:1-1 by 9.3, 6.7, and 3.3 days, respectively, while it was significantly delayed in OLPR, VIP, and OS-OLPR:1-1 by 12.3, 3.7, and 8.0 days, respectively. While the total biological yield was significantly reduced in OLPR, OS-OLPR:1-1, VIP, and OS-VIP:1-1, it was comparable to OS in OA, OA-OLPR:1-1, and OA-VIP:1-1 (597.0, 552.0, 532.2, and 556.2 g/kg, respectively). Production was consistently high over two consecutive flushes in OS, OA, and OA-VIP: 1-1. Total biological yields were higher in OA-OLPR: 1-1 than OS-OLPR:1-1 and in OA-VIP:1-1 than OS-VIP:1-1. OA increased mushroom number and firmness, VIP and OLPR increased mushroom weight, and OA-VIP:1-1 increased pileus thickness. Mushrooms' protein and fiber contents were higher than OS in all substrates and the highest in OA-OLPR:1-1 (8.7 %) and OLPR (2.8 %), respectively. Conclusively, the substrates OA, OA-VIP: 1-1, and OA-OLPR:1-1 may alternate oak sawdust; however, the first two substrates have an advantage over the third due to earlier harvests. Also, it is more favorable to use VIP and OLPR in combination with OA than to use them alone.

Bioconversion of rice straw by Lentinula edodes under different spawn formulations

To attend to the growing world demand for mushrooms, it is interesting to increase the system's productivity, improve quality and reduce production costs. This study aimed to optimize the production and quality of fruiting bodies of the edible and medicinal mushroom Lentinula edodes (shiitake), in agroresidues substrate using appropriate strain and spawn formulation. The evaluation was conducted using two strains under seven different spawn formulations (Control [C]: Sorghum grain + 2.5% CaCO3; (2) C + 2.5% sawdust; (T3) C + 5% sawdust; (T4) C + 2.5% peat; (T5) C + 5% peat; (T6) C + 1.25% sawdust + 1.25% peat; (T7) C + 2.5% sawdust + 2.5% peat) that were inoculated into the blocks at a proportion of 2% (w/w). The substrate was formulated with 63% rice straw, 20% sawdust, 15% wheat bran, and 2% CaCO3 and sterilized. The incubation period was 87 days. Two flushes were obtained. Adding small aliquots of peat and sawdust to the inoculum gave significantly higher morphological results than the control in all variables analyzed. The days required for the first harvest ranged from 87 to 94 days. The average weight of basidiomes ranged from 6.38 to 28.75 g. The productivity data show superior results for the treatments in which the spawn was supplemented with sawdust and peat. Enhanced bioconversion with supplemented spawn shows promises for yield and composition improvement, crucial for commercial viability. It can be concluded that shiitake production using agroresidues such as straw can be increased using a suitable strain/spawn for optimal production.

Chromosomal genome and population genetic analyses to reveal genetic architecture, breeding history and genes related to cadmium accumulation in Lentinula edodes

BACKGROUND

Lentinula edodes (Berk.) is the second most productive mushroom in the world. It contains compounds effective for antiviral, antitumor, antioxidant and immune regulation. Although genomes have previously been reported for this species, a high-quality chromosome-level reference for L. edodes is unavailable. This hinders detailed investigation of population genetics, breeding history of strains and genes related to environmental stress responses.

RESULTS

A high-quality chromosome-level genome was constructed. We separated a monokaryon from protoplasts of the commercial L. edodes strain L808 and assembled the genome of L. edodes using PacBio long-read and Illumina short-read sequencing, along with the high-throughput chromatin conformation capture (Hi-C) technique. We assembled a 45.87 Mb genome, and 99% of the sequences were anchored onto 10 chromosomes. The contig and scaffold N50 length were 2.17 and 4.94 Mb, respectively. Over 96% of the complete Benchmarking Universal Single-Copy Orthologs (BUSCO) were identified, and 9853 protein-coding genes were predicted. We performed population genome resequencing using 34 wild strains and 65 commercial cultivars of L. edodes originating from China, Japan, the United States and Australia. Based on whole-genome variants, we showed substantial differences in the Chinese wild population, which divided into different branches according to the main areas of their geographical distribution. We also determined the breeding history of L. edodes at the molecular level, and demonstrated that the cultivated strains in China mainly originated from wild strains from China and Northeast Asia. Phenotypic analysis showed that 99 strains exhibited differences on the Cd accumulation. Three significant loci in the of L. edodes genome were identified using the genome-wide association study (GWAS) of Cd accumulation traits. Functional genes associated with Cd accumulation traits were related to DNA ligase and aminoacyl tRNA synthetase, indicating that DNA damage repair and in vivo protein translation may be responses to Cd stress.

CONCLUSIONS

A high-quality chromosome-level genome and population genetic data of L. edodes provide genetic resources for functional genomic, evolutionary and artificial breeding studies for L. edodes.

Effect of Pretreated Colza Straw on the Growth and Extracellular Ligninolytic Enzymes Production by Lentinula edodes and Ganoderma lucidum

Lentinula edodes 3565 and Ganoderma lucidum 9621 were compared for their ability to produce lignocellulolytic enzymes in submerged (SM) and surface liquid (SL) fermentation of hydrolysed colza straw lignin waste that remained after the production of furfural and bioethanol (CS lignin). Application of cultivated mushrooms to dispose of pretreated colza straw agricultural waste is an approach to decrease the quantity of residual lignin while simultaneously obtaining active substances, e.g., the ligninolytic enzyme complex from mycelium. The effect of adding CS lignin to culture media on the yield of L. edodes and G. lucidum mycelium and extracellular laccase activity was studied. It was revealed that the mycelial growth of G. lucidum on solid media was significantly improved by adding CS lignin. Laccase activity during SL cultivation of L. edodes on medium with CS lignin gradually increased over the experiment starting on day 21 and peaked at 520 U/mL on day 28. G. lucidum expressed the maximum laccase activity, 540 U/mL, during the first 14 days of mycelium SM cultivation. Extracellular laccase activity was enhanced about 35- to 40-fold at cultivation of L. edodes and about 10- to 15-fold in the case of G. lucidum by supplementing liquid culture media with CS lignin.

Biomass estimation and physicochemical characterization of winter vine prunings in the Chinese and global grape and wine industries

The residual biomass of winter vine prunings (WVPs) in the Chinese and global grape and wine industries was investigated and estimated, and the physicochemical characteristics of Chinese WVPs were analyzed. The eight regions investigated within China showed a total annual regional WVP yield of 201-842 kt FW, with R1 and R6 region showing the highest and the lowest region yields, respectively. The R4 and R2 regions showed the highest and the lowest yield per tree. Table grapes showed considerably higher WVP yields than wine grapes, whereas the pergola systems showed considerably higher WVP yields than the hedge systems. In addition, older vines showed higher WVP yields than younger vines. Overall, the average WVP yield in China was 2.35 kg/tree FW with a range of 1.33-3.21 kg/tree FW. Globally, the estimated WVP yield has decreased gradually from 2000 to 2017 to 42.31 million ton FW; in contrast, estimated WVP yield in China has increased substantially over the same period to 6.04 million ton FW. Winter vine pruning was the leading source of solid grape waste in the grape and wine industry, both absolutely and proportionally, and was characterized by such properties as a high dry matter content, mild acidity, high levels of organic matter and nutrients, and low fat. It is clear that WVP represents a resource of immense value for generating additional wealth in China and in the global grape and wine industry.

Bioconversion of rice straw agro-residues by Lentinula edodes and evaluation of non-volatile taste compounds in mushrooms

Rice straw was substituted for sawdust at five different ratios of 0, 20%, 40%, 60%, and 80% (Control, RS20, RS40, RS60 and RS80, respectively) to obtain five kinds of Lentinula edodes. The effects of adding cropped rice straw to substrate formulas on the proximate composition and non-volatile taste compounds in mushrooms were investigated. The control group had the highest level of MY and BE among the five formulations. The protein levels in mushrooms decreased with the addition of rice straw and the ash levels increased. We found that trehalose, mannitol, and arabitol were the main soluble sugars in the five kinds of mushrooms. The contents of total free amino acids varied from 16.29 to 24.59 mg/g and the highest level of free amino acids was found in mushrooms cultivated from RS20 and RS40. Moreover, the addition of rice straw improved the contents of monosodium glutamate (MSG)-like amino acids in mushrooms. The 5′-Nucleotide levels ranged from 1.66 to 4.48 mg/g and equivalent umami concentration (EUC) value increased with the addition of rice straw. Our results suggest that rice straw is a potential substitute for sawdust to cultivate L. edodes with more non-volatile taste compounds.

Upgrading Grape Pomace through Pleurotus spp. Cultivation for the Production of Enzymes and Fruiting Bodies

Grape pomace, a by-product derived from winery industries, was used as fermentation media for the production of added-value products through the cultivation of two Pleurotus species. Solid-state (SSF), semiliquid (SLF), and submerged (SmF) fermentations were carried out using grape pomace as substrate. The effect of the different fermentations on the consumption of phenolic compounds, the production of mycelial mass and enzymes was evaluated using P. ostreatus and P. pulmonarius. The production of fungal biomass and enzymes was influenced by the fermentation mode. The maximum biomass values of ~0.5 g/g were obtained for both P. pulmonarius and P. ostreatus in SmF. Laccase production was induced in SSF and a maximum activity of 26.247 U/g was determined for P. ostreatus, whereas the highest endoglucanase activity (0.93 U/g) was obtained in the SmF of the same fungi. Analysis of phenolic compounds showed that both strains were able to degrade up to 79% of total phenolic content, regardless the culture conditions. Grape pomace was also evaluated as substrate for mushroom production. P. pulmonarius recorded the highest yield and biological efficiency of 14.4% and 31.4%, respectively. This study showed that mushroom cultivation could upgrade winery by-products towards the production of valuable food products.

Comparative transcriptome analysis of dikaryotic mycelia and mature fruiting bodies in the edible mushroom Lentinula edodes

Lentinula edodes is a popular cultivated edible mushroom with high nutritional and medicinal value. To understand the regulation of gene expression in the dikaryotic mycelium and mature fruiting body in the commercially important Korean L. edodes strain, we first performed comparative transcriptomic analysis, using Illumina HiSeq platform. De novo assembly of these sequences revealed 11,675 representative transcripts in two different stages of L. edodes. A total of 9,092 unigenes were annotated and subjected to Gene Ontology, EuKaryotic Orthologous Groups, and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Gene expression analysis revealed that 2,080 genes were differentially expressed, with 1,503 and 577 upregulated in the mycelium and a mature fruiting body, respectively. Analysis of 18 KEGG categories indicated that fruiting body-specific transcripts were significantly enriched in ‘replication and repair’ and ‘transcription’ pathways, which are important for premeiotic replication, karyogamy, and meiosis during maturation. We also searched for fruiting body-specific proteins such as aspartic protease, gamma-glutamyl transpeptidase, and cyclohexanone monooxygenase, which are involved in fruiting body maturation and isolation of functional substances. These transcriptomes will be useful in elucidating the molecular mechanisms of mature fruiting body development and beneficial properties, and contribute to the characterization of novel genes in L. edodes.

Relationship between environmental conditions, TRI5 gene expression and deoxynivalenol production in stored Lentinula edodes infected with Fusarium graminearum

This study made the first attempt to relate the production of deoxynivalenol (DON) to the expression of TRI5 gene in Fusarium graminearum as a function of interacting environmental factors (water activity (aw) (0.95-0.98), temperature (20-30 °C) and incubation time (7 day-28 day)), so as to investigate its production mechanisms in Lentinula edodes. Changes in temperature, water activity and incubation time could significantly (P<0.01) affect DON production and TRI5 gene expression. The highest DON concentration (793.5±27.4 μg/kg) and TRI5 gene expression (2−ΔΔCt=38.8±4.8) were observed when the cultures were incubated at 20 °C and 0.98 aw for 21 days. Multi-regression analysis was performed and nonlinear models based on polynomial equations were established to uncover the individual effects of temperature, water activity and incubation time as well as their interactions on DON production and TRI5 gene expression. The established model was further used to develop contour maps to predict the DON production and TRI5 gene expression in relation to storage conditions in L. edodes. Highly significant positive correlation between DON production and fold TRI5 gene expression (R=0.5534, P<0.0001) was observed in this commodity. The production mechanisms of DON in L. edodes revealed in the present study will be beneficial for developing more effective targeted control strategies.

Assessing the effects of different agro-residue as substrates on growth cycle and yield of Grifola frondosa and statistical optimization of substrate components using simplex-lattice design

Grifola frondosa is an economically important edible and medicinal mushroom usually produced on substrate consisting of sawdust supplemented with wheat bran. Cultivation of G. frondosa on crop straw (corn cob, corn straw, rice straw, and soybean straw) as a substrate was optimized by using the D-optimum method of the simplex-lattice design, and the alternative of crop straw as a substitute for sawdust in the substrate composition was determined by the optimized model. The results showed that there was a significant positive correlation existing between the yield and corn cob. The growth cycle was negatively correlated with sawdust, corn cob and soybean straw, with sawdust significantly shortening the growth cycle of G. frondosa. The optimized high-yielding formula included 73.125% corn cob, 1.875% rice straw, 23% wheat bran and 2% light calcium carbonate (CaCO₃) (C/N = 48.40). The average yield of the first flush was 134.72 ± 4.24 g/bag, which was increased by 39.97% compared with the control formula. The biological efficiency (BE) was 44.91 ± 1.41%, which was increased by 38.53% compared with the control. Based on the results of this study, corn cob can replace sawdust as one of the main cultivation substrates of G. frondosa.

Comparative secretomic analysis of lignocellulose degradation by Lentinula edodes grown on microcrystalline cellulose, lignosulfonate and glucose

Lentinula edodes has the potential to degrade woody and nonwoody lignocellulosic biomass. However, the mechanism of lignocellulose degradation by L. edodes is unclear. The aim of this work is to explore the profiling of soluble secreted proteins involved in lignocellulose degradation in L. edodes. For that, we compared the secretomes of L. edodes grown on microcrystalline cellulose, cellulose with lignosulfonate and glucose. Based on nanoliquid chromatography coupled with tandem mass spectrometry of whole-protein hydrolysate, 230 proteins were identified. Label-free proteomic analysis showed that the most abundant carbohydrate-active enzymes involved in polysaccharide hydrolysis were endo-β-1,4-glucanase, α-galactosidase, polygalacturonase and glucoamylase in both cellulosic secretomes. In contrast, enzymes involved in lignin degradation were most abundant in glucose culture, with laccase 1 being the predominant protein (13.13%). When the cellulose and cellulose with lignosulfonate secretomes were compared, the abundance of cellulases and hemicellulases was higher in cellulose with lignosulfonate cultures, which was confirmed by enzyme activity assays. In addition, qRT-PCR analysis demonstrated that the expression levels of genes encoding cellulases and hemicellulases were significantly increased (by 32.2- to 1166.7-fold) when L. edodes was grown in cellulose with lignosulfonate medium.

BIOLOGICAL SIGNIFICANCE

In this article, the secretomes of L. edodes grown on three different carbon sources were compared. The presented results revealed the profiling of extracellular enzymes involved in lignocellulose degradation, which is helpful to further explore the mechanism of biomass bioconversion by L. edodes.

Population genomic analysis uncovers environmental stress-driven selection and adaptation of Lentinula edodes population in China

The elucidation of genome-wide variations could help reveal aspects of divergence, domestication, and adaptation of edible mushrooms. Here, we resequenced the whole genomes of 39 wild and 21 cultivated strains of Chinese Lentinula edodes, the shiitake mushroom. We identified three distinct genetic groups in the Chinese L. edodes population with robust differentiation. Results of phylogenetic and population structure analyses suggest that the cultivated strains and most of the wild trains of L. edodes in China possess different gene pools and two outlier strains show signatures of hybridization between groups. Eighty-four candidate genes contributing to population divergence were detected in outlier analysis, 18 of which are involved in response to environmental stresses. Gene enrichment analysis of group-specific single nucleotide polymorphisms showed that the cultivated strains were genetically diversified in biological processes related to stress response. As the formation of fruiting bodies is a stress-response process, we postulate that environment factors, such as temperature, drove the population divergence of L. edodes in China by natural or artificial selection. We also found phenotypic variations between groups and identified some wild strains that have potential to diversify the genetic pool for improving agricultural traits of L. edodes cultivars in China.

Selective ligninolysis of wheat straw and wood chips by the white-rot fungus Lentinula edodes and its influence on in vitro rumen degradability

BACKGROUND

The present work investigated the influence of lignin content and composition in the fungal treatment of lignocellulosic biomass in order to improve rumen degradability. Wheat straw and wood chips, differing in lignin composition, were treated with Lentinula edodes for 0, 2, 4, 8 and 12 wk and the changes occurring during fungal degradation were analyzed using pyrolysis-gas chromatography-mass spectrometry and detergent fiber analysis.

RESULTS

L. edodes preferentially degraded lignin, with only limited cellulose degradation, in wheat straw and wood chips, leaving a substrate enriched in cellulose. Syringyl (S)-lignin units were preferentially degraded than guaiacyl (G)-lignin units, resulting in a decreased S/G ratio. A decreasing S/G ratio (wheat straw: r = -0.72, wood chips: r = -0.75) and selective lignin degradation (wheat straw: r = -0.69, wood chips: r = -0.88) were correlated with in vitro gas production (IVGP), a good indicator for rumen degradability.

CONCLUSIONS

L. edodes treatment increased the IVGP of wheat straw and wood chips. Effects on IVGP were similar for wheat straw and wood chips indicating that lignin content and 3D-structure of cell walls influence in vitro rumen degradability more than lignin composition.

Genome Sequence of the Edible Cultivated Mushroom Lentinula edodes (Shiitake) Reveals Insights into Lignocellulose Degradation

Lentinula edodes, one of the most popular, edible mushroom species with a high content of proteins and polysaccharides as well as unique aroma, is widely cultivated in many Asian countries, especially in China, Japan and Korea. As a white rot fungus with lignocellulose degradation ability, L. edodes has the potential for application in the utilization of agriculture straw resources. Here, we report its 41.8-Mb genome, encoding 14,889 predicted genes. Through a phylogenetic analysis with model species of fungi, the evolutionary divergence time of L. edodes and Gymnopus luxurians was estimated to be 39 MYA. The carbohydrate-active enzyme genes in L. edodes were compared with those of the other 25 fungal species, and 101 lignocellulolytic enzymes were identified in L. edodes, similar to other white rot fungi. Transcriptome analysis showed that the expression of genes encoding two cellulases and 16 transcription factor was up-regulated when mycelia were cultivated for 120 minutes in cellulose medium versus glucose medium. Our results will foster a better understanding of the molecular mechanism of lignocellulose degradation and provide the basis for partial replacement of wood sawdust with agricultural wastes in L. edodes cultivation.

Effects of Lentinula edodes consumption on biochemical, hematologic and oxidative stress parameters in rats receiving high-fat diet

PURPOSE

Functional foods can prevent/reduce the risks related to obesity. Lentinula edodes is a highly nutritious mushroom rich in protein, vitamins and minerals. Some studies have demonstrated the hypocholesterolemic effects from L. edodes in high doses, which does not represent the consumption in humans. We evaluated ingestion of a realistic dose of L. edodes associated with a high-fat diet (HFD) on hematologic, biochemical and oxidative stress parameters.

METHODS

Eighteen male Wistar rats were divided into three groups: control (normal diet); HFD; and HFD + L. edodes (100 mg/kg/day). After 30 days, blood was collected. Biochemical and hematologic parameters were analyzed, as well as oxidative stress biomarkers.

RESULTS

The HFD increased levels of total cholesterol and triglycerides. Lentinula edodes reduced these parameters significantly to concentrations found in the control group. The HFD increased levels of alanine transaminase and aspartate transaminase (markers of liver damage). Lentinula edodes returned the levels of these enzymes to normal levels and normalized serum levels of urea (which were also increased owing to consumption of the HFD). Lentinula edodes reduced levels of urea and glucose. Lipid peroxidation was increased in rats receiving the HFD, and L. edodes reduced malondialdehyde levels, thereby preventing oxidation of fatty acids.

CONCLUSIONS

Lentinula edodes was shown to have hypolipidemic, hypoglycemic, hepatoprotective and renoprotective features in doses that are suitable for humans.

Improvement of yield of the edible and medicinal mushroom Lentinula edodes on wheat straw by use of supplemented spawn

The research evaluated the interactions of two main factors (strain / types of spawn) on various parameters with the purpose to assess its effect on yield and biochemical composition of Lentinula edodes fruiting bodies cultivated on pasteurized wheat straw. The evaluation was made with four strains (IE-40, IE-105, IE-124 and IE-256). Different types of spawns were prepared: Control (C) (millet seed, 100%), F1 (millet seed, 88.5%; wheat bran, 8.8%; peat moss, 1.3%; and CaS0₄, 1.3%) and F2 (the same formula as F1, but substituting the wheat bran with powdered wheat straw). Wheat straw was pasteurized by soaking it for 1 h in water heated to 65 °C. After this the substrate (2 kg wet weight) was placed in polypropylene bags. The bags were inoculated with each spawn (5% w/w) and incubated in a dark room at 25 °C. A proximate analysis of mature fruiting bodies was conducted. The mean Biological Efficiency (BE) varied between 66.0% (C-IE-256) and 320.1% (F1-IE-124), with an average per strain of 125.6%. The highest mean BE was observed on spawn F1 (188.3%), significantly different from C and F2. The protein content of fruiting bodies was high, particularly in strain IE-40-F1 (17.7%). The amount of fat varied from 1.1 (F1-IE-40) to 2.1% (F2-IE-105) on dry matter. Carbohydrates ranged from 58.8% (F1-IE-40) to 66.1% (F1-IE-256). The energy value determined ranged from 302.9 kcal (F1-IE-40) to 332.0 kcal (F1-IE-256). The variability on BE observed in this study was significantly influenced by the spawn’s formulation and genetic factors of the different strains.

Mushroom as a product and their role in mycoremediation

Mushroom has been used for consumption as product for a long time due to their flavor and richness in protein. Mushrooms are also known as mycoremediation tool because of their use in remediation of different types of pollutants. Mycoremediation relies on the efficient enzymes, produced by mushroom, for the degradation of various types of substrate and pollutants. Besides waste degradation, mushroom produced a vendible product for consumption. However, sometimes they absorb the pollutant in their mycelium (biosorption process) and cannot be consumed due to absorbed toxicants. This article reviews the achievement and current status of mycoremediation technology based on mushroom cultivation for the remediation of waste and also emphasizes on the importance of mushroom as product. This critical review is also focused on the safety aspects of mushroom cultivation on waste.

Constructing a new integrated genetic linkage map and mapping quantitative trait loci for vegetative mycelium growth rate in Lentinula edodes

The most saturated linkage map for Lentinula edodes to date was constructed based on a monokaryotic population of 146 single spore isolates (SSIs) using sequence-related amplified polymorphism (SRAP), target region amplification polymorphism (TRAP), insertion-deletion (InDel) markers, and the mating-type loci. Five hundred and twenty-four markers were located on 13 linkage groups (LGs). The map spanned a total length of 1006.1 cM, with an average marker spacing of 2.0 cM. Quantitative trait loci (QTLs) mapping was utilized to uncover the loci regulating and controlling the vegetative mycelium growth rate on various synthetic media, and complex medium for commercial cultivation of L. edodes. Two and 13 putative QTLs, identified respectively in the monokaryotic population and two testcross dikaryotic populations, were mapped on seven different LGs. Several vegetative mycelium growth rate-related QTLs uncovered here were clustered on LG4 (Qmgr1, Qdgr1, Qdgr2 and Qdgr9) and LG6 (Qdgr3, Qdgr4 and Qdgr5), implying the presence of main genomic areas responsible for growth rate regulation and control. The QTL hotspot region on LG4 was found to be in close proximity to the region containing the mating-type A (MAT-A) locus. Moreover, Qdgr2 on LG4 was detected on different media, contributing 8.07 %-23.71 % of the phenotypic variation. The present study provides essential information for QTL mapping and marker-assisted selection (MAS) in L. edodes.

Quantitative changes in the biochemical composition of lignocellulosic residues during the vegetative growth of Lentinula edodes

The chemical changes in barley-straw (BS), wheat-straw (WS) and vineyard-pruning (VP) substrates were determined during colonization of Lentinula edodes mycelia (during primordium development) in solid state fermentation. Primordia appeared 39-50 days after inoculation. VP appeared to promote early sporophore initiation. The concentration of hemicellulose in BS and VP decreased gradually from 25.5% to 15.6% and from 15.8% to 12.3%, respectively. However in WS, hemicellulose decreased from 27.2% to 9.5%. Lignin broke down continuously in BS and WS, with 31.8% and 34.4% degradation, respectively; higher than that of cellulose. During the pinning stage, the C:N ratio decreased in VP and BS, but not in WS. On all substrates the phenols decreased notably throughout the first week of mycelial growth. The time elapsed (days) to pinning was positively correlated with cellulose content (r=0.89), total sugar (r=0.85) and inversely correlated to lignin (r=-1.00) and phenol content (r=-0.55).