Open Access
Comparative genomics of Ceriporiopsis subvermispora and Phanerochaete chrysosporium provide insight into selective ligninolysis
(National Academy of Sciences, 2012) Fernández Fueyo, Elena; Ruiz Dueñas, Francisco J.; Ferreira, Patricia; Floudas, Dimitrios; Lavín Trueba, José Luis; Oguiza Tomé, José Antonio; Pérez Garrido, María Gumersinda; Pisabarro de Lucas, Gerardo; Ramírez Nasto, Lucía; Santoyo Santos, Francisco; Producción Agraria; Nekazaritza Ekoizpena
Efficient lignin depolymerization is unique to the wood decay basidiomycetes, collectively referred to as white rot fungi. Phanerochaete chrysosporium simultaneously degrades lignin and cellulose, whereas the closely related species, Ceriporiopsis subvermispora, also depolymerizes lignin but may do so with relatively little cellulose degradation. To investigate the basis for selective ligninolysis, we conducted comparative genome analysis of C. subvermispora and P. chrysosporium. Genes encoding manganese peroxidase numbered 13 and five in C. subvermispora and P. chrysosporium, respectively. In addition, the C. subvermispora genome contains at least seven genes predicted to encode laccases, whereas the P. chrysosporium genome contains none. We also observed expansion of the number of C. subvermispora desaturase-encoding genes putatively involved in lipid metabolism. Microarray-based transcriptome analysis showed substantial up-regulation of several desaturase and MnP genes in wood-containing medium. MS identified MnP proteins in C. subvermispora culture filtrates, but none in P. chrysosporium cultures. These results support the importance of MnP and a lignin degradation mechanism whereby cleavage of the dominant nonphenolic structures is mediated by lipid peroxidation products. Two C. subvermispora genes were predicted to encode peroxidases structurally similar to P. chrysosporium lignin peroxidase and, following heterologous expression in Escherichia coli, the enzymes were shown to oxidize high redox potential substrates, but not Mn2+. Apart from oxidative lignin degradation, we also examined cellulolytic and hemicellulolytic systems in both fungi. In summary, the C. subvermispora genetic inventory and expression patterns exhibit increased oxidoreductase potential and diminished cellulolytic capability relative to P. chrysosporium.
Open Access
Metatranscriptomics sheds light on the links between the functional traits of fungal guilds and ecological processes in forest soil ecosystems
(Blackwell Scientific Publications Ltd, 2023) Auer, Lucas; Buée, Marc; Fauchery, Laure; Lombard, Vincent; Barry, Kerrie; Clum, Alicia; Copeland, Alex; Daum, Chris; LaButti, Kurt; Singan, Vasanth; Yoshinaga, Yuko; Martineau, Christine; Castillo Martínez, Federico; Alfaro Sánchez, Manuel; Imbert Rodríguez, Bosco; Ramírez Nasto, Lucía; Castanera Andrés, Raúl; Pisabarro de Lucas, Gerardo; Finlay, Roger; Lindahl, Björn D.; Olson, Ake; Séguin, Armand; Kohler, Annegret; Henrissat, Bernard; Grigoriev, Igor V.; Martin, Francis; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura; Institute for Multidisciplinary Research in Applied Biology - IMAB
Soil fungi belonging to different functional guilds, such as saprotrophs, pathogens, and mycorrhizal symbionts, play key roles in forest ecosystems. To date, no study has compared the actual gene expression of these guilds in different forest soils. We used metatranscriptomics to study the competition for organic resources by these fungal groups in boreal, temperate, and Mediterranean forest soils. Using a dedicated mRNA annotation pipeline combined with the JGI MycoCosm database, we compared the transcripts of these three fungal guilds, targeting enzymes involved in C- and N mobilization from plant and microbial cell walls. Genes encoding enzymes involved in the degradation of plant cell walls were expressed at a higher level in saprotrophic fungi than in ectomycorrhizal and pathogenic fungi. However, ectomycorrhizal and saprotrophic fungi showed similarly high expression levels of genes encoding enzymes involved in fungal cell wall degradation. Transcripts for N-related transporters were more highly expressed in ectomycorrhizal fungi than in other groups. We showed that ectomycorrhizal and saprotrophic fungi compete for N in soil organic matter, suggesting that their interactions could decelerate C cycling. Metatranscriptomics provides a unique tool to test controversial ecological hypotheses and to better understand the underlying ecological processes involved in soil functioning and carbon stabilization.
Open Access
Isolation, molecular characterization and location of telomeric sequences of the basidiomycete Pleurotus ostreatus var. florida
(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2006) Pérez Garrido, María Gumersinda; Pisabarro de Lucas, Gerardo; Ramírez Nasto, Lucía; Producción Agraria; Nekazaritza Ekoizpena
The white rot fungus Pleurotus ostreatus is an edible basidiomycete of increasing biotechnological interest due to its ability to degrade both wood and chemicals related to lignin degradation products. Telomeres are specialized structures at the end of all eukaryotic chromosomes. Ensure chromosome stability and protect the ends from degradation and from fusing with other chromosomes. Telomeres sequences are extraordinary highly conserved in evolution. The loss of telomeric repeats triggers replicative senescence in cells. For identification of restriction telomeric fragments in a previously described linkage map of Pleurotus ostreatus var. florida (Larraya et al., 2000), dikaryotic and eighty monokaryotic genomic DNAs were digested with diferents restriction enzymes (BamHI, BglII, HindIII, EcoRI, PstI, SalI, XbaI and XhoI) electrophoresed and transferred to nylon membranes. Numerous polymorphic bands were observed when membranes were hibridized with human telomericd probe (TTAGGG)132 (heterologous probe). Telomeric restriction fragments were genetically mapped to a previously described linkage map of Pleurotus ostreatus var.florida, using RFLPs identified by a human telomeric probe (tandemly repeating TTAGGG hexanucleotide). Segregation of each telomeric restriction fragment was recorded as the presence vs. absence of a hibridizing band. Segregation data for seventy three telomeric restriction fragments was used as an input table to be analysed as described by Ritter et al. (1990) and by Ritter and Salamini (1996) by using the MAPRF program software. Seventeen out of twenty two telomeres were identified. Telomere and telomere-associated (TA) DNA sequences of the basidiomycete Pleurotus ostreatus were isolated by using a modified version of single- specific-primer polymerase chain reaction (SSP-PCR) technique (Sohapal et al., 2000). Telomeres of Pleurotus ostreatus contain at least twenty five copies of non-coding tandemly repeated sequence (TTAGGG).
Open Access
Identification and functional characterisation of ctr1, a Pleurotus ostreatus gene coding for a copper transporter
(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2006) Peñas Parrila, María Manuela; Azparren Larraya, María Goretti; Domínguez, A.; Sommer, H.; Ramírez Nasto, Lucía; Pisabarro de Lucas, Gerardo; Producción Agraria; Nekazaritza Ekoizpena
Copper homeostasis is primordial for life maintenance and especially relevant for ligning-degrading fungi whose phenol-oxidase enzymes depend on this micronutrient for their activity. In this paper we report the identification of a gene (ctr1), coding for a copper transporter in the white rot fungus Pleurotus ostreatus, in a cDNA library constructed from four-days old vegetative mycelium growing in submerged culture. The results presented here indicate that: (1) ctr1 functionally complements the respiratory deficiency of a yeast mutant defective in copper transport supporting the transport activity of the Ctr1 protein; (2) ctr1 transcription is detected in all P. ostreatus developmental stages (with exception of lamellae) and is negatively regulated by the presence of copper in the culture media; (3) ctr1 is a single copy gene that maps to P. ostreatus linkage group III; and (4) the regulatory sequence elements found in the promoter of ctr1 agree with those found in other copper related genes described in other systems. These results provide the first description of a copper transporter in this white rot fungus and open the possibility of further studies on copper metabolism in higher basidiomyetes.
Open Access
Molecular characterization of A cellobiohydrolase gene family in the fungus Pleurotus ostreatus
(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2006) Eizmendi Goikoetxea, María Arantzazu; Sannia, Giovanni; Ramírez Nasto, Lucía; Pisabarro de Lucas, Gerardo; Producción Agraria; Nekazaritza Ekoizpena
Cellulose is the most abundant biological polymer on Earth. Its chemical composition consists of D-glucose units linked by β-1,4- glycosidic bonds forming linear polymeric chains with a reducing and a non-reducing end. Cellulose chains may either adhere to each other, via hydrophobic and van der Waals interactions, forming crystalline structures or remain more loosely packaged (amorphous cellulose). Consequently, the physical structure and morphology of native cellulose is complex and not uniform. Biological degradation of cellulose depends on the action of three types of enzymes: endoglucanases (E.C.3.2.1.4), cellobiohydrolases (E.C.3.2.1.91) and β-glucosidases (E.C.3.2.1.21). All them hydrolyse β-1,4-glycosidic bonds but they differ on the substrate specificity. Endoglucanases hydrolyse the amorphous regions of the cellulose fibbers generating new reducing and non-reducing ends, cellobiohydrolases attack the molecule ends yielding cellobiose units, and β-glucosidases hydrolyse cellobiose molecules yielding glucose. Cellobiohydrolases can be classified into two groups: type I (CBHI) and type II (CBHII), each having opposite chain-end specificities. CBHI prefer the reducing ends while CBHII act at non-reducing ends. By the screening of a genomic library from the basidiomycete Pleurotus ostreatus var. florida, we have isolated five cbhI genes, named cbhI1, cbhI2, cbhI3, cbhI4 and cbhI5, proving the occurrence of a multigenic family coding for this enzymatic activity. Using this sequences as probe, it has been possible to know the conditions in which are expressed those genes. This has allowed the synthesis of the each gene cDNA and, by comparison of this sequence with the corresponding genomic sequence, the characterization of their structure. On the other hand, using the RFLP technique and a progeny of 80 monokaryons derived from the dikaryon N001, the five genes have been mapped on the linkage map of P. ostreatus var. florida mapping the cbhI1 to the chromosome IV and the others to the chromosome VI.
Open Access
Selection of Pleurotus ostreatus strains in a genetic breeding program
(Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, 2006) Idareta Olagüe, Eneko; Jurado Cabanillas, Javier; Pisabarro de Lucas, Gerardo; Ramírez Nasto, Lucía; Producción Agraria; Nekazaritza Ekoizpena
The basidiomycete Pleurotus ostreatus, commonly known as oyster mushroom, is the second largest edible mushroom crop behind the white button mushroom, Agaricus bisporus. It accounts for nearly one-quarter of the total worldwide mushroom production. Furthermore, P. ostreatus has a high industrial interest because it is a good source of enzymes and other products with biotechnological, industrial and medical applications, it is easy to cultivate and because of its good organoleptic characteristics. Since of 2003, our group research has carried out genetic breeding programs based on the determination of QTLs controlling production and quality in industrial cultures of this fungus. In this breeding program the first test consisted in putting under fructification conditions 130 strains obtained from the crossing of protoclon PC21 (P. ostreatus var. ostreatus wild strain) by a collection of monokarions derived from N001 (P. ostreatus var. florida commercial strain). For this purpose, 2 kg (3 repetitions per strain) bags of industrial sustrate were inoculated and cultivated at 21ºC. Mature fruiting bodies were collected and weighted daily during the fructification period. The second test was made using the six strains that performed the better in Test1, but were cultivated at 18ºC and with 15 repetitions per strain were performed. From this test, three strains were selected and used in Test3. In this test, other three strains obtained from the crossing between monokarions descending of N001 and selectioned for their high growth rate were introduced. In this test the weight of the bags was increased to 5 kg and the cultures were cultivated at 18ºC. The strains obtained from PC21 have good charactericts for mushroom size, with similar behaviour for yield and precocity. The strains obtained from the crosses between N001 descendants have better mushroom size and similar yield and precocity than N001, then breeding was obtained. The candidate strains for next tests are PC21xMA046 and PC21xMA027 for their high yield and the mushroom good features.
Open Access
Mapping of genomic regions (quantitative trait loci) controlling production and quality in industrial cultures of the edible basidiomycete Pleurotus ostreatus
(American Society for Microbiology, 2003) Larraya Reta, Luis María; Alfonso Esquíroz, Mikel; Pisabarro de Lucas, Gerardo; Ramírez Nasto, Lucía; Producción Agraria; Nekazaritza Ekoizpena; Gobierno de Navarra / Nafarroako Gobernua
Industrial production of the edible basidiomycete Pleurotus ostreatus (oyster mushroom) is based on a solid fermentation process in which a limited number of selected strains are used. Optimization of industrial mushroom production depends on improving the culture process and breeding new strains with higher yields and productivities. Traditionally, fungal breeding has been carried out by an empirical trial and error process. In this study, we used a different approach by mapping quantitative trait loci (QTLs) controlling culture production and quality within the framework of the genetic linkage map of P. ostreatus. Ten production traits and four quality traits were studied and mapped. The production QTLs identified explain nearly one-half of the production variation. More interestingly, a single QTL mapping to the highly polymorphic chromosome VII appears to be involved in control of all the productivity traits studied. Quality QTLs appear to be scattered across the genome and to have less effect on the variation of the corresponding traits. Moreover, some of the new hybrid strains constructed in the course of our experiments had production or quality values higher than those of the parents or other commercial strains. This approach opens the possibility of marker-assisted selection and breeding of new industrial strains of this fungus.
Open Access
Comparative and transcriptional analysis of the predicted secretome in the lignocellulose-degrading basidiomycete fungus Pleurotus ostreatus
(Wiley, 2016) Alfaro Sánchez, Manuel; Castanera Andrés, Raúl; Lavín Trueba, José Luis; Oguiza Tomé, José Antonio; Ramírez Nasto, Lucía; Pisabarro de Lucas, Gerardo; Producción Agraria; Nekazaritza Ekoizpena; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Fungi interact with their environment by secreting proteins to obtain nutrients, elicit responses and modify their surroundings. Because the set of proteins secreted by a fungus is related to its lifestyle, it should be possible to use it as a tool to predict fungal lifestyle. To test this hypothesis, we bioinformatically identified 538 and 554 secretable proteins in the monokaryotic strains PC9 and PC15 of the white rot basidiomycete Pleurotus ostreatus. Functional annotation revealed unknown functions (37.2%), glycosyl hydrolases (26.5%) and redox enzymes (11.5%) as the main groups in the two strains. When these results were combined with RNA‐seq analyses, we found that the relative importance of each group was different in different strains and culture conditions and the relevance of the unknown function proteins was enhanced. Only a few genes were actively expressed in a given culture condition in expanded multigene families, suggesting that family expansi on could increase adaptive opportunities rather than activity under a specific culture condition. Finally, we used the set of P. ostreatus secreted proteins as a query to search their counterparts in other fungal genomes and found that the secretome profiles cluster the tested basidiomycetes into lifestyle rather than phylogenetic groups.
Open Access
Strain degeneration in pleurotus ostreatus: a genotype dependent oxidative stress process which triggers oxidative stress, cellular detoxifying and cell wall reshaping genes
(MDPI, 2021) Pérez Garrido, María Gumersinda; Lopez-Moya, Federico; Chuina Tomazeli, Emilia; Ibañez Vea, María; Garde Sagardoy, Edurne; López Llorca, Luis V.; Pisabarro de Lucas, Gerardo; Ramírez Nasto, Lucía; Institute for Multidisciplinary Research in Applied Biology - IMAB; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Strain degeneration has been defined as a decrease or loss in the yield of important commercial traits resulting from subsequent culture, which ultimately leads to Reactive Oxygen Species (ROS) production. Pleurotus ostreatus is a lignin-producing nematophagous edible mushroom. Mycelia for mushroom production are usually maintained in subsequent culture in solid media and frequently show symptoms of strain degeneration. The dikaryotic strain P. ostreatus (DkN001) has been used in our lab as a model organism for different purposes. Hence, different tools have been developed to uncover genetic and molecular aspects of this fungus. In this work, strain degeneration was studied in a full-sib monokaryotic progeny of the DkN001 strain with fast (F) and slow (S) growth rates by using different experimental approaches (light microscopy, malondialdehyde levels, whole-genome transcriptome analysis, and chitosan effect on monokaryotic mycelia). The results obtained showed that: (i) strain degeneration in P. ostreatus is linked to oxidative stress, (ii) the oxidative stress response in monokaryons is genotype dependent, (iii) stress and detoxifying genes are highly expressed in S monokaryons with symptoms of strain degeneration, (iv) chitosan addition to F and S monokaryons uncovered the constitutive expression of both oxidative stress and cellular detoxifying genes in S monokaryon strains which suggest their adaptation to oxidative stress, and (v) the overexpression of the cell wall genes, Uap1 and Cda1, in S monokaryons with strain degeneration phenotype indicates cell wall reshaping and the activation of High Osmolarity Glycerol (HOG) and Cell Wall Integrity (CWI) pathways. These results could constitute a hallmark for mushroom producers to distinguish strain degeneration in commercial mushrooms.
Open Access
Transcriptional and enzymatic profiling of Pleurotus ostreatus laccase genes in submerged and solid-state fermentation cultures
(American Society for Microbiology, 2012) Castanera Andrés, Raúl; Pérez Garrido, María Gumersinda; Omarini, Alejandra; Alfaro Sánchez, Manuel; Pisabarro de Lucas, Gerardo; Faraco, Vicenza; Amore, Antonella; Ramírez Nasto, Lucía; Producción Agraria; Nekazaritza Ekoizpena; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The genome of the white rot basidiomycete Pleurotus ostreatus includes 12 phenol oxidase (laccase) genes. In this study, we examined their expression profiles in different fungal strains under different culture conditions (submerged and solid cultures) and in the presence of a wheat straw extract, which was used as an inducer of the laccase gene family. We used a reverse transcription- quantitative PCR (RT-qPCR)-based approach and focused on determining the reaction parameters (in particular, the reference gene set for the normalization and reaction efficiency determinations) used to achieve an accurate estimation of the relative gene expression values. The results suggested that (i) laccase gene transcription is upregulated in the induced submerged fermentation (iSmF) cultures but downregulated in the solid fermentation (SSF) cultures, (ii) the Lacc2 and Lacc10 genes are the main sources of laccase activity in the iSmF cultures upon induction with water-soluble wheat straw extracts, and (iii) an additional, as-yet-uncharacterized activity (Unk1) is specifically induced in SSF cultures that complements the activity of Lacc2 and Lacc10. Moreover, both the enzymatic laccase activities and the Lacc gene family transcription profiles greatly differ between closely related strains. These differences can be targeted for biotechnological breeding programs for enzyme production in submerged fermentation reactors.