WSMBMP
Bulletin Number 6. January 31st, 2012
Dr. John BuswellDr. John Buswell Institute of Edible Fungi, Shanghai Academy of Agricultural Sciences, 1018 Jinqi Road, Shanghai 201403, P.R. China.

*Drawn from the title of the 1955 film release, "The Trouble with Harry", directed by Alfred Hitchcock

The huge diversity exemplified by mushrooms is clearly evident considering that representatives of these 'higher fungi' are to be found within two phyla, the Basidiomycota and Ascomycota. However, during my boyhood days in England, my knowledge of edible species was confined to the field mushroom (Agaricus campestris) and the blewitt (Lepista nuda) that my father and I collected on Saturday mornings in fields around Leicestershire and Northamptonshire for the Sunday breakfast 'fry-up'. However, in 1990, on joining the Department of Biology at The Chinese University of Hong Kong (headed at that time by the eminent mushroom biologist, Professor Shu-ting Chang), the blinkers were removed and I was introduced to the plethora of different mushrooms that are common components of the everyday Chinese diet. Among these, a particular favourite of mine, from both a research and culinary standpoint (they have a delicious flavour and texture but are devilishly difficult to eat with chopsticks -the first troublesome feature!), is the paddy straw mushroom, Volvariella volvacea.


There are numerous features associated with V. volvacea that make it 'troublesome' to researchers and growers even in the context of overall mushroom diversity. Thought to have originally been cultivated in China in the early 19th Century, V. volvacea is sometimes referred to as the "warm mushroom" because of its relatively high growth temperature (the optimum temperatures for vegetative growth, and for the formation of primordia and fruit body development, are 30-35 oC and 30-32 oC, respectively), and is very fast growing compared with most other cultivated species (Chang, 1978). However, despite two centuries of cultivation, biological efficiency values (i.e. conversion of growth substrate into mushroom fruit bodies) for V. volvacea are still very low (about 10% on rice straw) compared with many of the major cultivated edible mushroom species such as Agaricus bisporus, Lentinula edodes and Pleurotus spp (Chang, 1974). Although increased biological efficiencies have been achieved since the introduction of high cellulose cotton waste 'composts' (Chang, 1974), there is still considerable scope for improvement, and the mechanism(s) underlying the relatively poor yields remain unclear. Recent research undertaken at the Institute of Edible Fungi (IEF) at the Shanghai Academy of Agricultural Sciences, have implicated nutritional deficiencies arising during the first fruiting cycle (Hou, Chen, Li and Tan, unpublished) although other possible causes, including the formation of toxic substances, the development of inhibitory microflora or under-performing/deficient enzymes (see below) involved in substrate degradation, cannot be ruled out. In this latter context, transformation of a multi-functional cellulase gene, mfc, from Ampullaria crossean into V. volvacea by PEG-mediated protoplast transformation increased the average biological efficiency of the transformants to 27.84 ± 3.21% (compared to 20.63 ± 2.59% in non-transformed controls) in large scale cultivation experiments (Zhao et al. 2010).

The observation that V. volvacea grows and fruits better on cotton waste compared with paddy straw and 'woody' substrates such as sawdust suggested a limited ability to degrade the lignin component of lignocellulosic materials commonly used for mushroom cultivation. Although the capacity of the fungus to degrade lignin using a definitive assay such as the release of 14CO2 from 14C-ring-labelled DHP (dehydropolymerisate of coniferyl alcohol) (Haider and Trojanowski, 1975) does not yet appear to have been tested, no lignin peroxidase or manganese-dependent peroxidase activity (two key enzymes in lignin degradation by known ligninolytic fungi) have so far been detected in cultures of V. volvacea grown under a variety of growth conditions (Buswell et al, 1996). However, two isoforms of laccase, another enzyme long associated with lignin degradation, are produced when the fungus is grown either in submerged culture or on cotton waste "composts", but expression profiles suggest roles in sporophore development and detoxification rather than delignification (Chen et al, 2004). More recently, Dapeng Bao and coworkers at the IEF have identified eleven 'laccase' sequences within a draft V. volvacea genomic sequence (Bao et al, 2010) although, since the encoded proteins have been isolated and the catalytic function established in only two cases, nine of these 'laccase' sequences must, for the present, remain tentative. The group is currently engaged in isolating the remaining gene products, testing them for laccase activity and, where confirmed, assigning physiological roles to the different isoforms.

Another two features associated with V. volvacea that are not shared by other cultivated mushrooms is the loss of viability occurring when fungal mycelium is maintained at temperatures below 15 oC, and autolysis of the mushroom fruit body when stored at 4 oC (Chang, 1978). Preclusion of post-harvest refrigeration means a relatively short shelf-life and impedes wider market distribution of the mushroom. These features, combined with the high temperatures necessary for vegetative growth and fruiting of Volvariella volvacea also restrict industrial-scale cultivation to tropical and subtropical regions, thereby limiting the wider industrial exploitation of this important edible species. In order to overcome this constraint, IEF researchers are engaged in developing commercially viable, cold tolerant strains of V. volvacea capable of growing and fruiting in temperate climes. One such strain, VH, obtained by mutagenesis of V. volvacea protoplasts, survives for up to ten days at 4 oC and produces normal fruit bodies (Han et al, 2004). The mechanism(s) underlying these 'cold-shock' effects are still unclear. However, Mingjie Chen, Wang Hong and colleagues at the IEF have used Differential Display Reverse Transcription-PCR to identify 78 cold-induced DNA fragments, 12 of which were confirmed by Southern hybridization using cDNA from normal and cold-induced straw mushroom mycelium. Using cold-induced fragments as probes, cDNA clones were obtained from a cDNA library of V. volvacea and six complete cDNA sequences for putative cold-shock proteins have been deposited in GenBank. One sequence showed a high level of homology with known cold-resistance genes from plants. More recent data have indicated that low expression levels of a gene encoding for S-adenosyl-L-homocysteine hydrolase may be linked to the low temperature sensitivity of V. volvacea mycelium (Wang et al, 2010). V. volvacea, transformed by particle bombardment with the cDNA encoding a thermal hysteresis protein isolated from the Swedish Arctic insect spruce budworm, was more cold tolerant than the non-transformed host strain (Guo et al, 2005).

Four genetic mechanisms for controlling sexual morphogenesis in fungi have been identified, namely bipolar and tetrapolar heterothallism and primary and secondary homothallism. In keeping with its other unusual features, V. volvacea is reported to be a primary homothallic fungus (Chang, 1978), a comparatively much less frequent sexuality pattern among basidiomycetes. Here, homokaryotic mycelium, derived from a single meiotic parent, has the potential to undergo transition to the dikaryotic morphology and complete the sexual cycle. However, unlike the other defined sexuality patterns, the genetic determinants controlling sexuality in V. volvacea have yet to be identified and their relationship to heterothallic counterparts clarified.

Finally, there is the 'troublesome' issue of the phylogeny of V. volvacea, which has traditionally been assigned to the family Pluteaceae (Agaricales, Basidiomycota). An earlier phylogenetic analysis of the Agaricales based on nuclear large subunit (nLSU) data, undertaken by Moncalvo et al (2002) clustered V. volvacea with Fistulina Bull. and Schizophyllum Fr. in a very distant position. However, this assignment was not supported in a more recent reassessment of the taxonomic status of the genus Volvariella using data based on nLSU, nuclear small subunit (nSSU) and internal transcribed spacer (ITS) data (Justo et al. 2011). In this analysis, most of the representatives of the genus Volvariella fell outside the Pluteoid clade, and V. volvacea was consistently placed in one of two distinct Volvariella clades together with V. bombycina, which clustered with the hygrophoroid genera Camarophyllus and Cantharocybe. The authors concluded that "more research on additional genes and taxa is still needed to further clarify the position of Volvariella among the Agaricales."

Clearly, the trouble with Volvariella volvacea isn't over.

Acknowledgements: My thanks to Professors Shu-ting Chang and David Hibbett, and to Drs Mingjie Chen, Dapeng Bao, Hong Wang and Alfredo Justo, for helpful comments and the provision of data, some unpublished, used in the preparation of this article.


References:

Bao, D.P., Zhao, G.P., Tan Q., Wang S.Y., Chen, M.J., Zheng, H.J., Zhang, J.S., Zhu, Y.Q., Wang, H., Kang, H., Chen X., Lin, N. and Feng, A.P. (2010). Draft squence of the Volvariella volvacea genome. Acta Edulis Fungi. 17:1-5.

Buswell, J.A., Cai, Y.J., Chang, S.T., Peberdy, J.F., Fu, S.Y. and Yu, H.-s. 1996. ignocellulolytic enzyme profiles of edible mushroom fungi. World. J. Microbiol. Biotechnol. 12:537-542.

Chang, S.T. 1974. Production of the straw mushroom, (Volvariella volvacea) from cotton wastes. Mushroom J. 21:348-354.

Chang, S.T. 1978. Volvariella volvacea. In: The Biology and Cultivation of Edible Fungi. Chang, S.T. and Hayes, W.A., eds., Academic Press:New York, pp. 573-605.

Chen, S.C., Ge, W. and Buswell, J.A. 2004. Molecular cloning of a new laccase from the edible straw mushroom Volvariella volvacea: possible involvement in fruit body development. FEMS Microbiol. Lett. 230:171-176.

Guo, L.Q., Lin, J.F., Xiong, S. and Chen, S.C. 2005. Transformation of Volvariella volvacea with a thermal hysteresis protein gene by particle bombardment. Acta Microbiologica Sinica. 45:39-43.

Haider, K. and Trojanowski, J. 1975. Decomposition of specifically 14C-labelled phenols and dehydropolymers of coniferyl alcohol as models for lignin degradation by soft and white-rot fungi. Arch Microbiol. 105:33-41.

Han, Y.J., Chen, M.J., Cao, H. and Pan, Y.J. 2004. Selection for cold-resistant strain by complex mutagenesis of Volvariella volvacea and identification. Mycosystema. 23:417-422.

Justo, A., Vizzini, A., Minnis, A.M., Menolli Jr., N., Capelari, M., Rodríguez, O., Malysheva, E., Contu, M., Ghignone, S. and Hibbett, D.S. 2011. Phylogeny of the Pluteaceae (Agaricales, Basidiomycota): Taxonomy and character evolution. Fungal Biol. 115:1-20.

Moncalvo, J.M., Vilgalys, R., Redhead, S.A., Johnson, J.E., James, T.Y., Aime, M.C., Hofstetter, V., Verduin, S.J.W., Larsson, E., Baroni, T.J., Thorn, R.G., Jacobsson, S., Clémençon, H., Miller Jr, O.K.Jr. 2002. One hundred and seventeen clades of euagarics. Mol. Phylogen. Evol. 23:357-400.

Wang, H., Chen, M.J., Feng, A.P. and Qiao, N. 2010. Expression of a low temperature induced S-adenosyl L-homocyteine hydrolase gene (Cor 3) in a low temperature sensitive strain and a cold tolerant mutant of Volvariella volvacea. Acta Edulis Fungi. 17:14-21.

Zhao, F.Y., Lin, J.F., Zeng, X.L., Guo, L.Q., Wang, Y.H. and You, L.R. 2010. Improvement in fruiting body yield by introduction of the Ampullaria crossean multi-functional cellulase gene into Volvariella volvacea., Bioresource Technol. 101, 6482-6486.



Professor Shu-ting Chang with a harvest of Volvariella volvacea fruit bodies


The author with the China Pavilion at the 2010 World Expo in the background



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Dr. Jean Michel SavoieDr. Jean Michel Savoie INRA, Mycology and Food Safety,Bordeaux, France

Research on mushroom biology and mushroom cultivation started at the National Research Institute for Agronomy, INRA, in the southwest part of France, the Aquitaine, in 1974. Thirty-seven years of research with several generations of mushroom scientists, included only one International congress held in France. It was Mushroom Science X, the congress of ISMS, 32 years ago. Consequently, I was very enthusiastic when the World Society for Mushroom Biology and Mushroom Products proposed to organize its seventh International conference in France. The task was enormous, and with my colleagues we did our best for offering conditions for fruitful discussions and exchange of information about new findings in all the aspects of mushroom biology and mushroom products. The organization of such an event would not be possible without the generous support of the sponsors of the conference. I express my gratitude to them.




The conference was hosted at Arcachon, a beautiful seaside resort surrounded by golden sand lying at the mouth of the Bassin d'Arcachon - a rare inlet on the long, straight, west coast of France. The conference center was situated on the seafront boulevard promenade and with the sweet sun of the beginning of October, the delegates had to resist to the call for the beach. Fortunately some of them used their pre- and post- conference time for visiting Arcachon or the great wine capital of Bordeaux, a classical French city listed as one of UNESCO's World heritage sites since 2007.

Participants (217) from 41 countries representing each continent attended the conference. They were mainly scientists and students but also growers and staff of companies involved in the mushroom industry. During the conference they met with colleagues and friends in a relaxed atmosphere, with some convivial times around the excellent lunch buffets and during wine tastings. Collaborations were strengthened between mushroom scientists and with persons involved or interested in all aspects of the Mushroom Industry, including Edible and Medicinal Mushrooms, delegates, and representatives of the sponsors or at their exhibition stands.

The program contained 74 oral presentations including 9 invited lectures, 65 posters, 5 roundtable discussions and 5 companies were represented in exhibitions. Half of the contributions came from a group of seven countries: India, China, Japan, Brazil, Mexico, France, and The Netherlands. A book of abstracts of all oral presentations and posters was edited and it is available on the web page of the conference: https://colloque.inra.fr/icmbmp7. The Proceedings of the conference contain contributions submitted by the participants and selected by the scientific committee divided in two volumes: Volume 1 for the oral presentations and Volume 2 for the posters. They are published on the web site of the World Society for Mushroom Biology and Mushroom Products: http://www.wsmbmp.org/Previous_Conference_7.html. I gratefully acknowledge the work of the scientific committee members and some other colleagues for their contribution to editing these proceedings.

The conference commenced at 15:00 on Tuesday, 4th October for registration at the conference location in the Convention Centre of Arcachon. Meanwhile delegates were invited to taste wines produced by INRA: Château Couhins. In the evening, a welcome cocktail was offered by Amycel-Spawnmate Company, one of the partners of ICMBMP7. This afternoon and evening was a great opportunity to meet with colleagues and friends in a relaxed atmosphere.

On Wednesday morning Dr. José Sánchez, president of the WSMBMP, introduced the conference, and Didier Dupin, director of ANICC (the French Mushroom Growers Association) kicked off the talks with a presentation of the French and European organization and production of edible mushrooms.


The development of high-yielding strains of both well-established and more recently cultivated mushroom species using strain improvement and breeding technologies had been reported in the 6th International Conference (Bonn, Germany, 2008). Since 2008, the availability of the entire genome sequences of two important cultivated mushrooms, Lentinula edodes and Agaricus bisporus, has been a key development and data and perspectives were discussed during the ICMBMP7. In Session 1: Genomics, genetics and breeding, half of the talks and posters were on the button mushroom, Agaricus bisporus. This new opportunity and other developments of molecular approaches for advancing our knowledge and understanding of mushroom genetics and mushroom biology was a major feature of ICMBMP7. But these approaches are expensive and not available to all mushroom biologists. The interest of other breeding methods and selection was also discussed. The expected progresses in breeding lead to questions regarding ways to disseminate and protect newly developed strains. Sergio Semon from the European Community Plant Variety Office and Dr. Anton Sonnenberg (NL) animated a roundtable discussion on this question where points of view from various world regions were examined.

Evolution, taxonomy, and biodiversity are important topics for the development of new mushroom-derived products and the cultivation of new mushroom species. They were clearly identified in a session for the first time in the WSMBMP conferences. The eleven talks of Session 2 stressed that research output in these areas should offer a plethora of new opportunities, drive the choice of the species to be studied, contribute to quality insurance and influence policy makers in terms of biological resource preservation and management. This was discussed during the roundtable discussion animated by Jianping Xu (Ca) and Phillipe Callac (Fr).


Knowledge on the biology of mushrooms (their physiology, their life cycles, their development, their nutrition) is a source of information for the development of new mushroom cultivation methods or the improvements on conventional cultivation techniques. The seven talks and seven posters in the Session 3a revealed the interest of these topics and the progress expected from the use of genomic and proteomic data. Several oral presentations and posters reported on medicinal effects observed on cellular models and test animals (Session 3c), and others on mushrooms as sources of nutritional and active biomolecules (Session 3b). If there is to be confident in the use of such mushroom extracts and supplements for the treatment of various medical conditions, then the quality and production of the products needs to be standardized and regulated. There is a major lack of such regulation at the moment, and it is essential that progress be made in this area in the future to give consumers confidence and to protect public health from substandard products. The conference addressed this question by contributing to the dissemination of scientifically validated information and proposing discussions between participants from different continents.

Technological developments in the mushroom industry in general have resulted in increased production capacities, innovations in cultivation techniques, improvements in the quality of the final products, and the utilization of the natural qualities of mushrooms for environmental benefits. Among them a special interest could be addressed to the mycorrhizal mushroom to which an interesting small session (Session 5) was dedicated. Oral presentations and posters in Session 4 and Session 6 showed the importance of edible and medicinal mushroom cultivation in integrated management of agricultural wastes products. However, significant challenges remain in maintaining and further improving the current cultivars and cultivation techniques for mushroom production, in reducing mushroom diseases by integrated pest management, and in continuing to seek out new opportunities.

The conference ended on Friday, 7th October evening, with a presentation by the chairpersons of each session on what had been learnt in sessions and roundtable discussions. Before that, a special ceremony was organized by the WSMBMP for the new recipient of the WSMBMP Outstanding Researcher Award, Dr. Daniel Royse, Professor of Plant Pathology at the Pennsylvania State University, USA. He was the president of the World Society for Mushroom Biology and Mushroom products from 1997 to 2008. Congratulation to Dan.



The success of such a conference is dependent on the active participation of the delegates. On behalf of the organizing committee of ICMBMP7, I would like to thank all the contributors for their presentations of excellent standard. I use this opportunity to say a hearty "Thank" you to my colleagues of the Research group on mushroom genetics and biology and each person who helped me in the adventure of the conference organization.

I am looking forward to attending the 8th International Conference on Mushroom Biology and Mushroom Products to be held in 2014 and measuring the progresses in mushroom science since ICMBMP7.




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Dr.Katsuji YamanakaDr.Katsuji Yamanaka, Kyoto-Mycological Institute Kyoto,Japan

Dear colleagues and friends

The First International Conference on Mushroom Biology and Mushroom Products was held at the Chinese University of Hong Kong in August 1993 organized by Professor S. T. Chang and his colleagues. In one of the abstracts of the Conference, Prof. Chang described mushroom biology as providing the central knowledge for both mushroom science and mushroom biotechnology. Mushroom science and mushroom biotechnology deal with the principles and practices of mushroom cultivation and mushroom products. Now, 19 years after the 1993 Conference, the topics and questions at that time should continue to be addressed for the research and the production of mushrooms in the present and the future.

Mushroom production in Asia has dramatically increased in recent years with estimated production in China accounting for about 87% of the total world mushroom production in 2008. The production of specialty mushrooms such as Lentinula, Pleurotus and Flammulina has increased markedly in a large number of countries mainly in Asia. About 95% of the world's production of cultivated specialty mushrooms except for Agaricus is produced in China, Japan and Korea.

Mushroom producers worldwide face common problems such as increasing production costs, how to effectively use waste substrate and mushroom disease and pest control. Improvement of cultivation technologies used for specialty mushroom production is also of utmost importance. We should address the new problems by lively discussion at our International Conferences on Mushroom Biology and Mushroom Products.

Finally, we must work constantly to tout the WSMBMP for mushroom scientists, mushroom professionals and students in many countries. As the Co-Vice-President of the WSMBMP, I intend to support the President and other Executive committee members with their efforts to foster continued growth of the WSMBMP.






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Dr. José E. SánchezDr. José E. Sánchez, El Colegio de la Frontera Sur, México

WSMBMP activities

Our No. 6 bulletin is presented here on time, and although the first month of 2012 is already gone, we would like to send to everyone our best wishes of success and happiness for this year. Yes, undoubtedly time passes very quickly - we already have for this year only 11 months to go...

Year 2011 was an excellent time for WSMBMP. Dr. Jean Michel Savoie and his research group at INRA did an excellent job organizing the 7th International Conference held last October in Arcachon, France. This conference was both academically and logistically a great success, and according to the Proceedings (that you may download at the Society's official website, www.wsmbmp.org), delegates from 41 countries from all continents attended the meeting at the Palais des Congrès. Overall, 139 research articles were presented (among keynote lectures and oral and poster presentations) in three days.

Visitors to Arcachon, marvelous, with small streets and typical French architecture enjoyed excellent weather with breezy and salty wind. The Palais de Congrès, located directly in front of the beach, with soft sand and a warm seawater (warmer than normal for a week of October) was an excellent venue for the conference! Of course, the meals were of the highest quality: we didn't dare miss oysters in one of the rare oyster-producing regions of the world and, of course, the excellent French cuisine accompanied with excellent wines from the region de Bordeaux.

During the Conference, Society members met to discuss the Society's activities. First, the President and Treasurer made their respective activities reports for the last three years. Among the most important events, the Society's website was created and the Society's Bulletin was launched. Since the beginning, the website has been regularly visited. The trend of visits to the website since the startup in May 2010 up to the beginning of the Conference is shown in Fig. 1. A total of 3,228 visits were registered during the period, averaging 6.2 visits per day. The Bulletin has already issued 6 volumes and is published online every six months. The Treasurer, Dr. Alma Rodríguez, informed us that membership is slowly growing and although the Society is economically in good standing, more activities must be developed to rise funding.

After the Society's report, members present voted for proposed new council members. Two new members were unanimously accepted to join the council - Dr. Katsuji Yamanaka (Japan) was elected Vice-President and Dr. Andras Geosel (Hungary) was elected as a Council Member. They are very welcome to the Council and replaced outgoing members Dr. Shekhar Sharma (United Kingdom) and Dr. Hyun-Sook Lee (Republic of Korea) who gave great support to the Council during the past three years.

Another aspect discussed during the meeting was the risk of overlapping of our every three-year Conference with those of 2- and 4-year Conferences on Medicinal Mushrooms and the International Society for Mushroom Science, respectively. We all voted to have our next conference three years from now (in 2014) and thereafter, opting for a Conference every four years. By doing so, we will avoid overlapping our conference with other mushroom-related societies.

Figure 1. Cumulative number of visitors to WSMBMP web site, since its beginning on April 1, 2010.

One of the subjects that is still to be defined is where the next conference -the 8CMBMP- will be held. During the past 7th Conference, at the members' meeting, an Indian delegation expressed its willingness to celebrate the next WSMBMP conference in New Delhi in 2014. However, after further correspondence with members of the delegation, they shall need to fulfill several requirements within the government and within their research Council (IRCA) before confirming their commitment to organize the conference. We shall wait and keep you informed about developments in deciding where the 8CMBMP will be held.

During the Conference in Arcachon, the WSMBMP registered its first three Corporate Members: HONGO'S BIOFACTORY, SHII-TAKE RIOJA and UNICORN BAGS. As you probably know, Corporate Members are companies whose main activities relate to mushroom science and/or mushroom technology, and have a special concern for the development and dissemination of knowledge on mushrooms around the world. Each corporate member has its logo displayed in the Corporate Members' sections of our Society's website. We are pleased to welcome them and invite other mushroom-related companies to become Corporate Members of WSMBMP.

Finally, it is worthwhile to mention that at the end of the Conference, Dr. Daniel J. Royse (The Pennsylvania State University, USA) was named as the Outstanding Researcher Award for this 3-year period. The Awards Committee based his election on the more than 300 research papers about mushrooms authored or co-authored by Dr. Royse during 30+ years of research, his commitment to promote edible mushroom research in many countries, and his contribution to the promotion of mushroom biology worldwide. Dr. Royse was first a Council Member of WSMBMP and later he was the Society's President for 11 years. Congratulations, Dr. Royse!

The WSMBMP wishes all of you a great year in 2012!



The opening ceremony, the welcoming cocktail, the sea from the Dune and the beautiful town of Arcachon.





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About this bulletin

The WSMBMP Bulletin is the official electronic publication of the World Society for Mushroom Biology and Mushroom Products. The bulletin is intended to keep members informed about Council activities and to share general information about mushrooms. It is designed to allow communication between society members and alert them about new topics and opportunities related to mushrooms. Society members and general public are kindly invited to submit letters, comments and information of interest for the mushroom community to be published in the bulletin. Please submit your contributions electronically in free format to the editors José E. Sánchez (esanchez@ecosur.mx), Helen Grogan (helen.grogan@teagasc.ie) and Daniel J. Royse (djr4@psu.edu)




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