BSPP News Summer 2002 - Online Edition

The Newsletter of the British Society for Plant Pathology
Number 42, Summer 2002

IV Conference on Mushroom Biology and Mushroom Products
Cuernavaca, Mexico :  20 - 23 February 2002

The fourth conference on Mushroom Biology and Mushroom Products was held in the delightful city of 'Eternal Spring', Cuernavaca, which is about 80 km from Mexico City.  The weather was absolutely fabulous for February, especially coming from a rather wet and cold England, with warm sunshine and balmy evenings being the order of the day. 

The Conference itself had a varied programme covering many aspects of mushroom biology and mushroom products.  There was one full session on mushroom diseases along with a few pathology-related presentations during other sessions. 

Dr Danny Rinker presented an excellent review on the potential uses of spent mushroom substrate around the world, with an extensive literature review on all work done to date, including its use in pest and disease control.   His paper will be an extremely  useful resource in the coming years as researchers try to find ways of utilizing this potentially valuable by-product.

One of the most intriguing papers of the conference was that of keynote speaker Dr Jerald Pataky of the University of Illinois, USA.  Dr Pataky is a pathologist, who works primarily on common smut of sweet corn, caused by Ustilago maydis. Infected ears of corn produce galls, which start off light coloured and then turn silvery black as the teliospores mature.  His work is largely concerned with looking for host resistance to this disease in sweet corn hybrids because, in the USA, even a small proportion of the disease within a crop can significantly reduce revenue due a downgrading of sweet corn quality.  While developing an inoculation technique with which to measure susceptibility in sweet corn hybrids, he was contacted by a person from Mexico who happened to hear about his research and who had quite a different interest in this disease.  In Mexico, the galls of common smut are known as  "Huitlacoche" (pronounced "wheat-la-coach-eh") and are a highly prized delicacy, known since Precolumbian times. Dr Pataky began a programme of research in the mid 1990's trying to maximise the production of huitlacoche from a culinary perspective, and had Mexican chefs in the wings to evaluate the quality of his product.  He found that inoculation of maize silks between 6-8 days after mid-silk growth stage, gave the best yield of huitlacoche; while the best quality of huitlacoche was harvested 16-17 days after inoculation. Teliospores mature at this time, which was important as immature galls were not considered of culinary value.  Based on an estimated price for huitlacoche of US $12 a lb, Dr Patakys trials were commercially viable, despite the additional costs associated with growing the crops under experimental conditions.   We had the opportunity to have some tortilla's filled with huitlacoche one lunchtime, and the experience was certainly "different" and "interesting".

Dr Michelle Mamoun, from INRA Bordeaux, France, presented very interesting data concerning compost green mould, a serious disease of the cultivated mushroom caused by Trichoderma harzianum molecular type Th2.  Michelle showed how the compost-colonising Th2 isolates of T. harzianum were superior in their ability to germinate and grow in mushroom compost although exocellular enzyme activities of Th2 and non-Th2 isolates were similar.  This adaptation to mushroom compost was associated with an ability to resist 24 out 27 bacterial antagonists in the compost whereas non-Th2 isolates were significantly inhibited by 10 bacterial isolates.  Although compost green mould is less of a problem in Britain now compared with the late 1980's and early 1990's, this disease continues to be a problem for some growers in mainland Europe, as well as in North America and Mexico where a different biotype (Th4) is implicated.  Composting technology within the mushroom industry has undergone significant changes in the past 10 years or so and it may be that changes in compost microflora have allowed T. harzianium Th2 and Th4 to flourish.

Mr Patrick Callopy of Penn State University, USA gave an interesting presentation on genetic variation in populations of Verticillium fungicola, the causitive organism of dry bubble disease of the cultivated mushroom Agaricus bisporus.  Patrick found that ITS sequence data indicated the existance of geographic isolation between North American and European isolates with North American isolates grouping with ex-type strains of Verticillium fungicola var aleophilum while European strains grouped with V. fungicola var fungicola.  He also demonstrated a phylogenetic relationship between both V. fungicola varieties and the insect-pathogen genera Cordyceps and Paecilomyces, suggesting the genera may share a common ancestry that used a chitin substrate for growth.  This confirms the findings of other workers which suggest that Verticillium pathogens of mushrooms are not closely related to plant pathogenic Verticillium spp.  This is an exciting area of research within mushroom pathology and opens the way for further studies on the genetic relatedness of V. fungicola with entomopathogens

Dr Mark Wach reviewed the knowledge base of mushoom virus disease and described the emergence of a new virus disease in Britain.  I then presented initial research results from HRI on this pathogen, Mushroom Virus X, which has been affecting an increasing number of British mushroom growers since 1996.  The disease does not appear to occur in North America as yet, but has now been detected in Ireland and Holland, two major mushroom growing countries in Europe, and it may only be a matter of time before it occurs elsewhere.  At the moment we are characterising the many dsRNA's associated with the disease as well as developing rapid PCR diagnostics and elucidating the epidemiology of the disease. This is an exciting area of pathology research. 

I was very grateful to BSPP for the  travel grant which enabled me to attend this conference, not only to renew friendships and have extensive discussions with my fellow mushroom pathologists around the world but also to enhance my knowledge of some of the other aspects of mushroom science, that I do not routinely encounter.  That it all happened in a truly magnificent location was an added bonus, while the memory of the whole experience will provide me with much enthusiasm and energy for a while to come. 

Helen Grogan
Horticulture Research International, Wellesbourne.

Bioactive Fungal Metabolites: Impact and Exploitation

University of Wales, Swansea : 22 - 27 April 2001

Firstly, may I thank the BSPP for their financial contribution that enabled me to attend this conference. Delegates attending this BMS International Symposium described the meeting as "informative", "stimulating", "evocative", "vibrant" or "exciting".  These terms are totally apt. The symposium was held at the University of Wales Swansea, which is situated along a marvellous coastline on the panoramic Gower peninsula. I even had a lovely view of Swansea Bay from my bedroom window. The conference boasted over 260 participants from 44 countries and provided an ideal forum for people to meet each other and gain valuable contacts. The meeting was run extremely efficiently and credit for this must go to Dr Tariq Butt, the conference organiser. 

In the poster room, there was an excellent array of displays, including a 3-dimensional model of a yeast cell, showing metabolite pathways, created by Dr Henry Tribe. Other stands included those of Wolf Laboratories which displayed the latest technology in microscopes, and Thermo Labsystems, who created a lot of interest with their Vitotox Test System which detects genotoxicity and cytotoxicity using genetically modified Salmonella typhimurium. All the posters were of a very high standard and created much interest among the delegates. Whilst at the conference, I manned a stand for the BSPP, on which I displayed the now infamous t-shirts we offer. As well as Mike Cooke (founder member of the BSPP) coming by to say hello, there was a lot of interest in the stand (not least because I was next to the biscuits, sugar and milk). We gained at least 2 new members and sold several t-shirts, so keep an eye out for them, one of which will be worn by Professor Tjamos (University of Athens) on an expedition in Greece looking for plant pathogens. The BMS also had a very attractive stand that had on display wonderful, hand painted clay models of toadstools. 

On the first day, Professor Gary Strobel's talk on 'Gifts from the Rainforest' was a real eye opener. He made the point that there is a huge wealth of untapped resources on our plant and that non-destructive research in to areas such as rainforests can only benefit the disciplines of medicine and agriculture. As the sun shone, we heard about marine and mangrove fungi, toxic compounds from Fusarium sp. and mycotoxin biosynthetic pathways. 

Tuesday, in true British style, brought incessant rain. However, it did not dampen the spirits of delegates as we were too busy hearing about screening fungal compounds for toxicity (Richard Walmsley, UMIST) and radiolabelled precursors to identify novel fungal metabolites (Ana Miljkovic, King's College). In this technological society we live in, I imagine most people reading this article have e-mail. Well, the latest thing is the e-nose! Naresh Magan (University of Cranfield) talked about this wonderful technology, which detects volatile organic compounds emitted by all fungi, specifically with a view to detection of post-harvest spoilage organisms. The technology is so sensitive, it can detect the presence of a minute amount of a fungus (and identify it) before there are any visible signs. The potential for prevention of food waste is enormous and other uses include the detection of pathogenic bacteria and the monitoring of air quality. 

Wednesday's session on mycotoxins was wide-ranging, covering legislation, Fusarium mycotoxins in cereals, patulin in apple juice, detection of mycotoxins and toxigenic fungi, control of toxigenic fungi, effects of mycotoxins on pigs, cattle and poultry, and the role of mycotoxins in 'sick building syndrome'.
On Thursday, with the sun shining and seagulls flying overhead, the conference had a distinct holiday atmosphere. For me, the most interesting (and worrying) talk of the day was from Matt Ryan of CABI, on the effect of preservation and storage on metabolite profiles of fungal biocontrol agents. This MAFF-funded project has illustrated how secondary metabolite production is altered by sub-culturing, lyophilisation, storage in water and cryopreservation, and explains why, despite warnings from my supervisor, my experiments looking for antibiotic production did not work. The conclusions were that continuous sub-culture resulted in the most variation and cryopreservation, the least. The mechanisms of change still need to be investigated however, to determine whether the changes are phenotypic or genetic.  

Thursday came to a conclusion with the conference dinner and dance. The food was very tasty and there was a lively atmosphere as people took their partners by the hand and swung them around the room. I was witnessing my first ceilidh and flushed pink, but smiling faces were everywhere! The President of the BMS, Prof. Steven Moss thanked everyone for attending and remarked on how well everyone had mixed and got to know each other, making valuable contacts as well as friends. 

Friday morning saw a network discussion on opportunities for funding, where delegates had the chance to identify partners for funding and future collaborative research. Leaving the beach and the sunshine behind I headed back to London with renewed enthusiasm and many ideas for my own research, the conference having been a great success. 

Monica Maksymiak
University of Hertfordshire

Plant Microbe Interaction Day
Oxford : 19 April 2002 

Last Friday saw the first ever Oxford PMI meeting. Organised by Gail Preston (Dept Plant Sciences, Oxford) its intention was to bring together the growing number of workers in Oxford and beyond who investigate host-microbe interactions. Although the majority of speakers were from the department of Plant Sciences there were representatives from Zoology, Biochemistry, and the Centre for Ecology and Hydrology, as well as Dawn Arnold from University of West England (the brave non-Oxford speaker!). I for one did not realise the number of people who are investigating plant-microbe interactions - the numbers of people whose brains I can now pick has certainly increased!! It was good to see such a cosmopolitan meeting too, with speakers of Australian, Chinese and New Zealand nationalities.

Reflecting the broad disciplines of the speakers the talks were also wide ranging. The day was separated into four sessions: plants under pressure; signals and signal transduction; microbes in action; and once and future microbe interactions.

Marc Knight kicked off with a talk summarising the powerful techniques his lab uses to elucidate Arabidopsis signalling, including aqueorin to localise calcium fluxes and mutants to elucidate steps in signalling pathways. This idea of emphasising the techniques used in labs and their applications echoed many of the day's talks. A number were overviews of many years of work, with supervisors and post-docs summarising the techniques and work of their labs. This meant that the questions posed and discussed, were broad ranging and the talks on the whole insightful and smooth. As enjoyable as this was, perhaps it would also be one of the few criticisms of the day; if future events included more talks from PhD students this would add a valuable dimension to the proceedings.

Talks using novel techniques included one from Monika Tlalka who talked about 'Understanding Pulses in the Underground Wood Wide Web (www)'. In her work with Phanerochaete velutina, a foraging woodland fungus, beautiful images and video clips have been obtained using photon-counting scintillation imagery, to illustrate 'pulsing' in nutrient transport. 

I also enjoyed the talks by Catherine Pears (Development in Dictyostelium) and Jonathan Hodgkins (Investigating host-microbe interactions with the nematode Caenorhabditis elegans). Working on the rather intractable obligate fungus, Blumeria graminis, I enjoyed these two talks for the often novel ways their experimental organisms have to be investigated and their biology considered. Catherine Pears's group work on cell cycle control enzymes (cdks) and more general signalling. She discussed their search for a PKC equivalent in Dictyostelium and the molecular contenders found so far, including PIPkinA, which has been shown to be involved early in development and to affect gene expression. Jonathan Hodgkin discussed his lab's work on pathogenic bacteria of C. elegans. This latter talk was perhaps the most unusual of the day, with discussions of nematode constipation! Some pathogenic bacteria can stick to these nematodes, probably with glycoproteins as shown by lectin staining. As well as gaining a food supply, such behaviour may also protect the bacteria from being eaten as well as providing a form of transportation. 

The day was wrapped up with a talk by Paul Rainey, in which he posed the question 'why is Pseudomonas so diverse?' He explored the causes of diversity: ecological, physiological and genetical, with reference to Pseudomonas species. It was a fitting end to an interesting and successful day. Perhaps in further years such an event could be sponsored by the BSPP, to allow more speakers from outside of Oxford, and the provision of a lunch to allow more mingling with the speakers, which was difficult in such a busy programme.

Emma Perfect
University of Oxford