Below-ground ectomycorrhizal community in natural Tuber melanosporum truffle grounds and dynamics after canopy opening

[EN] The ectomycorrhizal fungus Tuber melanosporum fruits in association with Quercus in natural forests of Spain. Some of these stands are managed to keep an open canopy and meet the habitat requirements of the fungus. However, there are few quantitative studies analysing in these forests the relationship between soil environment and T. melanosporum. Eight forest stands which produce T. melanosporum have been monitored for 6 years in order to characterise the below-ground ectomycorrhizal community and to assess its temporal dynamics after experimental canopy opening. The brûlé, the ground where T. melanosporum fruits, shows a distinct ectomycorrhizal community, characterised by lower density of active ectomycorrhizal tips, lower morphotype richness per soil volume, higher abundance of T. melanosporum and lower abundance of Cenococcum geophilum than soil closest to the trunk of the host Quercus ilex. Opening the canopy has not stimulated an increase in T. melanosporum, suggesting that a shift in the soil environment alone will not trigger the formation of new truffières in the short term. The dry climate of these truffières may be a factor as T. melanosporum abundance appears to be sensitive to annual weather conditions. © 2011 Springer-Verlag.We gratefully acknowledge the support of the Conselleria de Medi Ambient (Generalitat Valenciana) and VAERSA. Comments from anonymous reviewers and editorial suggestions from Randy Molina greatly helped in improving the manuscript. The Fundacion CEAM is partly supported by Generalitat Valenciana, Fundacion Bancaja and the projects GRACCIE (Consolider-Ingenio 2010) and FEEDBACKS (Prometeo-Generalitat Valenciana).García Barreda, S.; Reyna Domenech, S. (2012). Below-ground ectomycorrhizal community in natural Tuber melanosporum truffle grounds and dynamics after canopy opening. Mycorrhiza. 22(5):361-369. doi:10.1007/s00572-011-0410-2S361369225Agerer R (1987–2002) Colour atlas of ectomycorrhizae 1st-12th del. Eihorn-Verlag, BerlinÁgueda B, Fernández-Toirán LM, De Miguel AM, Martínez-Peña F (2010) Ectomycorrhizal status of a mature productive black truffle plantation. For Syst 19:89–97Barry-Etienne D, Ricard JM, Diente S, Moundy PJ, Chandioux O, Fiorese D, Jaillard B, Serre F, Jourdan C (2008) Distribution of Tuber melanosporum mycorrhizas on rootstocks of holm-oaks (Quercus ilex) in production. 3º Congresso Internazionale di Spoleto sul Tartufo, Spoleto, ItalyBonet JA, Fischer CR, Colinas C (2001) Evolución mensual en campo de las ectomicorrizas de Tuber melanosporum Vitt. inoculadas en plantas de Quercus ilex. In: Actas del III Congreso Forestal Español. Junta de Andalucía. Available in http://www.congresoforestal.es . 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Can J For Res 36:2561–2573. doi: 10.1139/X06-143Martín-Benito D, Cherubini P, Del Río M, Cañellas I (2008) Growth response to climate and drought in Pinus nigra Arn. trees of different crown classes. Trees 22:363–373 doi: 10.1007/s00468-007-0191-6Mello A, Murat C, Bonfante P (2006) Truffles: much more than a prized and local fungal delicacy. FEMS Microbiol Lett 260:1–8. doi: 10.1111/j.1574-6968.2006.00252.xOlivier J-M, Savignac J-C, Sourzat P (2002) Truffe et trufficulture. Fanlac, Périgueux, FrancePargney JC, Chevalier G, Dupré C, Genet P, Jalade M (2001) Étude des stromas fongiques se développant sur les racines des plants mycorhizés par la truffe. In: Courvoisier M, Olivier JM, Chevalier G (eds) Actes du V Congrès International Science et Culture de la Truffe. Fédération Française des Trufficulteurs, Aix-en-Provence, France, pp 167–172Parsons WFJ, Miller SL, Knight DH (1994) Root-gap dynamics in a lodgepole pine forest: ectomycorrhizal and nonmycorrhizal fine root activity after experimental gap formation. Can J For Res 24:1531–1538. doi: 10.1139/x94-200Reyna S, Garcia S, Folch L, Pérez-Badia R, Galiana F, Rodríguez-Barreal JA, Domínguez-Núñez JA, Saiz de Omeñaca JA, Zazo J (2004) Selvicultura trufera en montes mediterráneos. In: Vallejo R, Alloza JA (eds) Avances en el estudio de la gestión del monte mediterránea. Fundación CEAM, Valencia, pp 523–546Ricard JM, Bergougnoux F, Callot R, Chevalier G, Olivier JM, Pargney JC, Sourzat P (2003) La truffe Guide technique de trufficulture. Ctifl, ParisSánchez-Durán S, De Miguel AM, Palazón C, González Armada B, Sáez R, Barriuso J (2009) Estado de micorrización de árboles truferos en función de su carácter productivo y su edad. In: Actas del 5º Congreso Forestal Español. 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Sex and tree rings: Females neither grow less nor are less water-use efficient than males in four dioecious tree species

Females of woody dioecious species usually expend more resources on reproduction than males. Therefore, it is expected that females incur greater costs of reproduction than males, and, as a result, trade-offs between reproduction and growth should emerge. The aim of this study is to test those hypotheses by analyzing the differences between genders regarding radial growth (basal area increment) and wood carbon isotope composition (d13C), a proxy of water-use efficiency. We compared these two variables in males and females of four dioecious tree species inhabiting drought-prone Mediterranean sites in Spain (Pistacia terebinthus, Ilex aquifolium, Juniperus thurifera and Ailanthus altissima). We analyzed the influence of sex on the radial growth patterns throughout the tree life considering the growth stage of individuals, the differences in the response of genders to climate variables (air temperature, precipitation and drought severity), and the d13C during a severe drought period. One site was studied for each species and 21–33 trees per species were sampled in each site. No differences in growth were found between genders for any of the four species throughout their life span. No significant interactions between gender and precipitation were found, although A. altissima males were more responsive to summer (June-July) temperature. No differences in d13C were found between genders excepting for P. terebinthus, indicating that the males of this species show a less efficient water use during drought events than the females. These results do not support the broad assumption that females of woody dioecious plants show lower growth and are less water-use efficient than males or that they respond differently to precipitation variability, except for P. terebinthus during drought events. Further analyses could be performed in other dioecious species inhabiting seasonally dry regions to confirm or reject our conclusions

Sequential application of inoculation methods for the mycorrhization of Quercus ilex seedlings with Tuber melanosporum

The use of mycorrhized seedlings has been critical in the success of modern truffle cultivation, which nowadays supplies most black truffles to markets. Ascospore inoculation has been traditionally used to produce these seedlings, but little scientific information is publicly available on the inoculation methods applied or on the possibility of combining them. We evaluated the potential of sequential inoculation for the controlled colonization of holm oak fine roots with black truffle, with two nursery assays and a full factorial design. Three inoculation methods were sequentially applied: radicle inoculation, inoculation of the substrate in seedling trays and inoculation of the substrate in the final pot. The sequential application appeared as an effective and realistic alternative for commercial inoculation of holm oak seedlings with black truffle. The increase in the amount of inoculum applied with each inoculation method improved the mycorrhizal colonization of seedlings, although separately none of the inoculation methods appeared clearly superior to the other ones. The depth distribution of mycorrhizae levels pointed to the inoculation in the final pot substrate as being more effective than other methods in lower parts of the root system, whereas the early inoculation appeared more effective to reduce the occurrence of the opportunist ectomycorrhizal fungus Sphaerosporella brunnea . However, the difference of results between both assays suggests that cultivation conditions and/or the timing of the nursery operations may influence the relative effectiveness of these inoculation methods.UnpublishedThis is a preprint; it has not been peer reviewed by a journal

Productos trufados: respuesta emocional del consumidor y análisis de veracidad de los mismos

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Biodeterioro microbiológico en shiitake (Lentinula edodes)

En la actualidad, el cultivo y el uso de hongos comestibles está suscitando un creciente interés en el sector gastronómico y en la industria farmacéutica, siendo Lentinula edodes (shiitake) uno de los principales, debido a sus características organolépticas y componentes bioactivos. Las setas son alimentos altamente perecederos, cuya vida útil escasamente supera las 2 semanas. Para prolongar su conservación en fresco garantizando su aptitud organoléptica y sanitaria, se han desarrollado y combinado diferentes tecnologías de barrera que, aun siendo asequibles y disponibles para la industria alimentaria, a día de hoy no están implantados. Por tanto, el objetivo principal ha sido profundizar en el conocimiento sobre las causas de biodeterioro de shiitake, y así establecer tecnologías que serían idóneas para su conservación. Para ello, se realizó un ensayo de vida útil de shiitake bajo tres condiciones de conservación: sin envasar a temperatura ambiente, sin envasar bajo temperaturas de refrigeración (4ºC), y envasadas en atmósfera modificada bajo temperaturas de refrigeración (4ºC). Semanalmente, se monitorizaron parámetros físico-químicos, microbiológicos y organolépticos, que establecieron el fin de la vida útil de los diferentes lotes. Además, al inicio y al final de la vida útil de cada lote se aislaron bacterias diferenciadas por su morfología colonial, para determinar si participan de forma activa en la degradación de los cuerpos fructíferos. La secuenciación de la región 16S del genoma permitió identificar la microflora asociada a esta especie. Posteriormente, los microorganismos aislados se inocularon en carpóforos de shiitake y de champiñón (Agaricus bisporus) para establecer las causantes del daño y se realizó un antibiograma con estas cepas enfrentándolas a micelio de shiitake para observar el efecto en su desarrollo. El fin de vida útil vino determinado por criterios organolépticos que, a su vez, estuvieron directamente relacionados con la pérdida de peso y el incremento de las poblaciones microbianas. Los carpóforos analizados presentaron una carga microbiana constituida principalmente por especies bacterianas pertenecientes al Gº Pseudomonas (4,7 log ufc/g), seguido de la Fª Enterobacteriaceae y la micobiota. La secuenciación permitió identificar 49 cepas bacterianas: 24 pertenecientes a la Fª Enterobacteriaceae, 21 pertenecientes al Gº Pseudomonas, 2 al Gº Micrococcus. 1 al Gº Burkholderia y 1 al Gº Paenibacillus. Los bioensayos efectuados han demostrado que las especies Burkholderia sp., Ewingella americana y Rahnella sp. se comportaron como micopatógenas al inocular sobre el carpóforo, siendo la última especie capaz de inhibir, de manera considerable, el crecimiento de micelio vegetativo de shiitake (Figura 1). El desarrollo de cebadores para una identificación rápida y eficaz de estas bacterias micopatógenas, permitiría una detección precoz y establecer medidas preventivas y correctivas, que reducirían las pérdidas económicas en la industria del cultivo de hongos, desde la producción de sustrato y micelio a la producción de carpóforos y comercialización

Response of Tuber melanosporum fruiting to canopy opening in a PinusQuercus forest

[EN] The wild production of the highly appreciated fungus Tuber melanosporum is negatively affected by canopy closure in the stand. Habitat improvement has been proposed as a tool to recover the production in close forests, but evaluations based on scientific monitoring are still lacking. This study analyses the short-term effect of a pilot project on improvement of T. melanosporum reproduction habitat. The results support the project hypothesis that the canopy closure was hampering truffle fruiting in the larger brines. The silvicultural treatment alone has not triggered a clear positive response in all the truffieres, suggesting that complementary actions are necessary to ensure their sustainability. Weather conditions provoke a year-to-year variation in the fruiting and determine the responsiveness of the truffieres to the treatment. (C) 2012 Elsevier B.V. All rights reserved.We gratefully acknowledge the support of the Conselleria de Medi Ambient (Generalitat Valenciana) and VAERSA. CEAM is partly supported by Generalitat Valenciana, Fundacion Bancaja and the projects GRACCIE (Consolider-Ingenio 2010) and FEEDBACKS (Prometeo-Generalitat Valenciana).Garcia Barreda, S.; Reyna Domenech, S. (2013). Response of Tuber melanosporum fruiting to canopy opening in a PinusQuercus forest. Ecological Engineering. 53:54-60. doi:10.1016/j.ecoleng.2012.12.006S54605

Reproductive phenology determines the linkages between radial growth, fruit production and climate in four Mediterranean tree species

The influence of climate on seed or fruit production and tree growth is a central question in forest ecology, with a key role on forest dynamics. However, the mechanisms linking inter- and intra-annual climate variability, fruiting and growth remain poorly understood, although they seem to be largely species-specific. The resource-matching hypothesis posits that fruit production responds to annual environmental variability, predicting a positive relationship between reproduction and growth, whereas other hypotheses such as resource switching or resource budget imply allocation trade-offs between reproduction and growth. Climate control over fruiting is thought to be more likely in variable, limiting environments such as those existing in seasonally dry Mediterranean forests. However, the studies about these forests are much scarcer than on temperate ecosystems, probably due to the sparseness and shortness of fruit production records. Here we analysed the relationships between monthly climate variables, tree-ring widths and fruit production at stand level in four tree species under different climatic conditions in Spain (12-27 trees and 24-54 radii were sampled in each site). For the species from xeric sites such as Pinus pinea, Castanea sativa and Quercus ilex, tree-ring width positively correlated with fruit production, as envisaged by the resource-matching hypothesis. This association was driven by prior wet winter climate conditions, which enhanced growth. Some of the significant correlations between climate variables and fruit yield corresponded to key reproductive phenophases. On the other hand, for the species from mesic sites (Abies alba) no positive growth–fruit production correlation was found, likely due to the mismatch in the effect of climatic factors on growth and fruiting. These results support the hypothesis that climatic conditions, particularly a positive water balance, play a major role as a proximate cause of fruit production in seasonally dry Mediterranean forests and underscore the importance of species-specific reproductive phenology traitsPublishe

Caracterización genotípica de cepas de B. cereus aisladas de especies de diferentes trufas

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Efecto de la temperatura y adición de trufa negra en la calidad de la carne de lechal y ternasco de Ojinegra de Teruel

Agradecimientos: AGROJI. Fondos FITE del Gobierno de Aragón “Construyendo Europa desde Aragón” (2016-653A)Publishe