1998 is the year that the world of plant pathology comes to Britain. As last year's BSPP Presidential Conference, "Plant Pathology: Global Perspectives of an Applied Science", showed, and many of the reports in this Newsletter confirm, the ever-increasing pace of international travel, trade and communication not only causes plant diseases to spread world-wide, but also the plant pathology expertise to combat them.
The International Congress offers British plant pathologists the chance to demonstrate the strengths and successes of our science, but will no doubt reveal areas in which we are weaker than other countries. The attitude of British government agencies to research plant pathology is strangely erratic: strong support has been given to molecular biology of disease resistance, in which Britain is certainly among the world leaders, while specialists in other areas, which have equal scientific interest and intellectual rigour but are currently less fashionable, are rapidly becoming endangered species.
There is a great danger of essential skills becoming lost through such an unbalnaced approach. When biotechnologists are ready to carry out large-scale field trials of resistant plants, will there still be epidemiologists to measure the level of disease control and quantify its benefits for yield and quality? Too many decisions on which areas to expand or contract have been made on ephemeral, quantitative, misleadingly quantitative data, a feeble way of juding the long-term worth of research, while little thought has been given to the erosion of expertise in plant pathology - not that our subject is alone in this.
ICPP98 will celebrate the diversity of plant pathology world-wide. It will show that research is worth doing because of its value for food production in a crowded world, even if, by not being directly relevant to north America or western Europe, it is not perceived as glamorous. It will also show that practical answers to real problems can only be reached by a broadly-based, multi-disciplinary approach.
by Nigel Hardwick, BSPP President 1997 and Graham Jellis, BSPP Secretary
A momentous decision for the Society was taken at the Annual General Meeting, held at the Presidential Conference at York University on 16 December 1997, when, by a unanimous verdict, the following motion was carried: "Council is instructed to proceed to the incorporation of the Society as a charitable company limited by guarantee. The company's Memorandum and Articles of Association will be those approved by the Charity Commissioners and will be based on the existing constitution of the Society".
The reasons behind the motion were notified to members in a letter written by the President and Secretary in advance of the AGM. It gave as the reason for the proposed change the possible risk to Members of Council as the Society's trustees for any legal actions taken against the Society. Members of Council can be liable to the full extent of their personal assets to meet any claims against the Society if it is in breach of contract. Incorporation also has other benefits as the Society would have its own legal identity and could hold property, enter into contracts and sue and be sued in its own name. Incorporation as a company limited by guarantee would limit the liability of an individual trustee to £10.
We had three written responses from members unable to attend the AGM. Two were for and one against the motion. The member against the proposal expressed concern that incorporation would put all the power into the hands of Council. One of the letters in support made the point that it could be difficult for subscribing members to remove Officers and Members of Council. The motion is explicit in that members are only giving approval for incorporation if the Articles of Association are based on the existing constitution. Council will ensure that this is the case.
We are currently engaged, through our solicitors (Martineau Johnson), in discussions with the Charity Commissioners, to amend the draft Articles of Association to meet our requirements. We want to keep the five-year rule for Officers and the three-year rule for Members of Council. Subscribing members would continue to elect Council by ballot. We also need to ensure that amendments to the Articles can only take place by a vote of the subscribing members at the AGM or an Extraordinary General Meeting called for the purpose.
We hope that we can get through all the necessary stages this year so that the next elections to Council and the December AGM will be under the Articles of Association as a charitable company limited by guarantee.
It is worth noting that this will be only the second time the constitution has been amended since the Society's formation in 1981. The first change was brought about because we wished to pay an honorarium to the Senior Editor of Plant Pathology in order to compensate him for the considerable amount of work this involves. This meant we had to remove the Senior Editor as an Officer of Council, as under charity law trustees cannot benefit financially from their position. To this end an EGM was held at the University of East Anglia in July 1989 to approve the proposed change to the constitution.
Progress on the move to incorporate will be reported in the next issue of the Newsletter and posted on our web-site.
Professor David Ingram,
BSc, PhD, MA, ScD, FLS, F.I.Biol, F.I.Hort, FRSE
David Ingram was born in the City of Birmingham in 1941, the son of a toolmaker and grandson of a gamekeeper. His parents instilled in him a belief in education as a means of achieving freedom. As a lad, following a game of Robin Hood, he pushed into the ground a willow stem that had been used as a bow; it took root, produced leaves, and the young Ingram became a botanist. Later he learned how to grow chrysanthemums, potatoes and other vegetables and saw how botany and horticulture were indissolubly linked.
At school he was taught geology by Dr Mabel Tomlinson, a great amateur geologist. She taught him the meaning of scholarship. After school, he was apprenticed as a gardener but soon realised that this was not the ideal route to health, wealth and happiness. He therefore decided to go to university and chose Hull because it would enable him to read botany in combination with geology and psychology. It was one of the most important decisions of his life, for there he met Professor Noel Robertson, a plant pathologist and an inspirational teacher. He showed him how a knowledge of plant science could contribute to agriculture and horticulture and first introduced him to the excitement of the study of plant diseases. After obtaining a degree in botany in 1963, David Ingram worked as Noel Robertson's research student and studied the interaction of Phytophthora infestans with tissue cultures of potato.
In 1966 he moved to the University of Glasgow, to work with another inspiring botanist, Professor Percy Brian. Brian taught him that there can be no boundaries in the thinking of a scientist - all science is one. During this time he extended his work on the interaction between pathogens and host tissue cultures, notably with Plasmodiophora brassicae, cause of clubroot of brassicas. This led to fascinating findings about the dual culture of obligate parasites and their hosts, and provided insights into the hormonal disturbance of host tissues that result from infections of plants by biotrophic fungi. A shared interest in clubroot led to a working frienship with Paul Williams of the University of Wisconsin.
In 1968, the young plant pathologist moved with Brian to Cambridge. First he worked as a Senior Scientific Officer in the old ARC Unit of Developmental Botany, and later became Lecturer in Plant Pathology in the University of Cambridge and a Fellow of Downing College. The work with clubroot continued and in collaboration with Inez Tommerup he was able to elucidate details of the life cycle of Plasmodiophora brassicae. He later collaborated with David Jones and Geoff Dixon in studies of single spore isolates. Next, his interests expanded to embrace Bremia lactucae and its lettuce host and with a variety of collaborators, including Philip Mason, Inez Tommerup, John Andrews, John Sargeant, Don Maclean, Richard Mitchelmore and Ian Crute and his team, he worked on the cytology and fine structure of the host-pathogen interaction, sexual reproduction and the development of oospores, and the genetic basis of virulence and avirulence.
Another branch of his work, pursued in collaboration with Richard Brettell, explored the potential for selecting maize lines resistant to T-toxin, using cell culture technology. Further aspects of in vitro selection were developed subsequently with oilseed rape and its pathogens in collaboration with, amongst others, Mary Macdonald, Ferre Aslam, Peter Loudon, Chiang-Shiang Loh and Dorothy Newsholme. At this time he met Marcello Buiatti, a Florentine geneticist and philosopher who was to have a profound influence on his thinking.
Now came studies of the light leaf spot pathogen, Pyrenopeziza brassicae, and its interaction with brassica hosts. Aspects of the sexual process were investigated with Terence Ilott, Chris Rawlinson, John Friend, Keith Johnstone, Alison Ashby and Anjum Siddig. With Sheila Maddock he investigated the host range and specificity of Pyrenopeziza brassicae. At about the same time he worked with Paul Dyer on sexual processes in the Ascomycetes and on diseases of Narcissus with Paul Nicholson.
A final series of collaborations with Keith Johnstone, Alison Ashby and Maria Murphy, led to molecular studies of the pathogenicity of Pyrenopeziza brassicae, and this work continues in Cambridge today.
Concurrently with his research work, David Ingram had developed a passion for teaching and enjoyed enormously his interactions with students both as a lecturer and as a tutorial supervisor. These interests were developed further through his Fellowship of Downing College, Cambridge, where he variously held the posts of Director of Studies in Biology, Dean and Tutor for Graduate Students.
Finally, towards the end of the 1980s, having become a Reader in Plant Pathology in Cambridge, David Ingram began to get itchy feet, and went off to the Plant Pathology Department of the University of Sydney as a Thurburn Fellow at the invitation of Brian Deverall. From a distance of 12000 miles he realised what he wanted to do next - become the Regius Keeper (Director) of the Royal Botanic Garden Edinburgh. He saw this post as providing an opportunity to combine his interests in plant science in its widest sense, plant biotechnology, his developing interests in schools science and promotion of the public understanding of science, and his very early interests in horticulture. On his return to the UK, he found to his amazement that the post of Regius Keeper had just been advertised in Nature. He applied, and the Trustees called his bluff by offering him the job.
Whilst in Edinburgh he has greatly enjoyed helping the Garden and its 200 staff to develop its scientific work in the fields of plant systematics, biodiversity studies and conservation. This led to a collaboration with Angela Karp of Long Ashton and the many other participant in an EC research project to develop molecular tools for the study of biodiversity. He also developed, in collaboration with Richard Price, the Science and Plants for Schools programme (funded by The Gatsby Charitable Foundation) to promote innovative ways of teaching plant science in the classroom. He is now Chairman of the Trustees of SAPS, which has reached 10,000 teachers through its workshops. He has also kept touch with plant pathology by studying sexual development in Pyrenopeziza brassicae with Maria Chamberlain.
Now, after over eight exciting years at the Royal Botanic Garden Edinburgh, during the year in which he is President of the British Society for Plant Pathology and of the 7th International Congress for Plant Pathology, two of the most important offices that he has ever held, he has decided to stand down as Regius Keeper to devote all of his energy to his interests in education and the public understanding of science, horticulture and conservation. He will remain in Edinburgh and will continue as a Professor in the Universities of Edinburgh and Glasgow. He will also continue as the first Honorary Professor of Horticulture of the Royal Horticultural Society.
Among David Ingram's publications are the books: "Tissue Culture Methods for Plant Pathologists" (with John Helgeson); "Plant Tissue Culture" (with Dennis Butcher); "The Cambridge Encyclopedia of Life Sciences" (with Adrian Friday); "Advances in Plant Pathology" (with Paul Williams); "Shape and Form in Plants and Fungi" (with Andrew Hudson); and "Molecular Tools for Screening Biodiversity" (with Angela Karp and Peter Isaac). He is currently writing a New Naturalist book on "The Natural History of Plant Disease" with Noel Robertson.
David Ingram met his wife, Alison (a teacher of English), at a bus stop in Hull. They have now been married for over 33 years and they have two grown-up sons, one a professional botanist, and the other a biology teacher, both of whom are also happily married; and David and Alison are now grandparents.
BSPP warmly welcomes the following new members, who have recently joined the Society:
Miss Alefyah Ali, a postgraduate student in London.
Mr Mohammad A Ali, of the Scottish Agricultural Science Agency, whose interests include viral and fungal pathogens of soft fruits and potato.
Prof. Madih Aly, who is at Ainshams University, Cairo, Egypt, and whose interests include control of fungal pathogens.
Mr Alex A Appiah, a postgraduate student at Imperial College, researching the molecular biology of plantation crop fungal pathogens.
Miss Lia S Arraiano, a postgraduate student at the John Innes Centre, Norwich, researching Septoria tritici of wheat.
Evangelos Athanassopoulos, a postgraduate student at Wye College, researching the molecular biology of Pseudomonas pathogens of beans.
Mr Arup K Bandapadhyay, of the Central Research Institute for Jute and Allied Fibres, India, whose interests include the epidemiology of fungal and rhizobacterial infections of fibre and other crops.
Miss J Anne Beare, a postgraduate student from Imperial College, researching rust pathogens of broad leaf trees.
Mr Mark H Bennett, from Wye College, whose interests include resistance of vegetable crops to necrotrophic fungal pathogens.
Dr Penny Brading, from the John Innes Centre, who is researching the resistance of wheat to Septoria tritici.
Mr Robert Burns, of the Scottish Agricultural Science Agency, who works on the development of monoclonal antibodies for plant pathogens.
Dr Bishwanath Chakraborty, of the University of North Bengal, India, whose interests include the diagnosis and control of fungal pathogens.
Mr Nick Chambers, a plant pathologist from Ashford, Kent.
Mr Jack Chipili, a postgraduate student from HRI Wellesbourne.
Dr Jeremy Clark, from Bristol.
Dr Rob Clayton, from SAC Aberdeen, whose interests include post-harvest pathology of cereals and potatoes.
Mr Martin PA Coetzee, a postgraduate student at the University of the Orange Free State, South Africa, working on the molecular biology of fungal pathogens of trees.
Mr Simon J Cooper, a postgraduate student at Cambridge University.
Dr Teresa A Coutinho, from the University of the Orange Free State, South Africa, whose interests include fungal forest pathogens.
Mrs Maureen Darling of the Scottish Agricultural Science Agency, whose interests include viral pathogens of potato and potato wart disease.
Mr William A J M Dawson, a postgraduate student at IACR-Rothamsted, working on necrotrophic pathogens of cereals and fungicides.
Mr Z Wilhelm De Beer, a post-graduate student at the University of the Orange Free State, South Africa, researching forest pathology.
Miss Juanita De Wet, a postgraduate student at the University of the Orange Free State, South Africa.
Miss Georgina Donovan, a postgraduate student at the University of Birmingham, working on the molecular biology of potyviruses.
Miss Wendy E Durrant, a postgraduate student at the Sainsbury Laboratory, Norwich, working on the molecular biology of resistance to fungal and viral pathogens.
Miss Lauren East, a postgraduate student at NRI, Kent, researching control of Colleotrichium and Pseudomonas infection on bananas and wild plants.
Miss Michelle Edwards, a postgraduate student at the University of the West of England, working on downy mildew.
Mrs Zelinger Einat, a postgraduate student at Oxford Brookes University.
Miss Sharon J Elcock, from CSL, York, whose interests include epidemiology of fungal pathogens.
Dr Jane Etheridge, who is at IACR-Rothamsted, working on fungal pathogens of cereals and lupins.
Wilbert G Flier, from IPO in The Netherlands.
Dr Michael F Foley, from Cambridge Plant Pathology Services Ltd., whose interests include diagnostics for fungal pathogens.
Dr Bagyanarayana Gaddam, of Osmania University, Hyderabad, India whose interests include control of fungal pathogens.
Dr Richard W Gibson, a virologist at NRI.
Dr Jeannie Gilbert, from the Cereal Research Centre at Agriculture and Agri-Food Canada.
Mr Tijs Gilles, a postgraduate student at IACR-Rothamsted.
Miss Sandra Goodfellow, who runs the potato nucleus stock facility at the Scottish Agricultural Science Agency, Edinburgh.
Mr Nicolas E Gosman, a postgraduate student at the John Innes Centre, researching the molecular genetics of Fusarium.
Dr Najmul Hasan, of the Indian Grassland and Fodder Research Institute, whose interests include control of nematode pathogens of fodder crops.
Prof. Chuji Hiruki, from the University of Alberta, Canada, whose interests include tree pathology.
Miss Karin Jacobs, a postgraduate student at the University of the Orange Free State, South Africa, working on Leptographinium.
Mr Nicolas S Jarrauld, a postgraduate student at Imperial College, researching Rhytisma acerinum and Diplocarpen rosae in broad leaf trees.
Miss Caroline S Jones, a postgraduate student at Alice Holt Lodge, working on fungal pathogens of trees.
Dr E Eirian Jones, from HRI Wellesbourne, whose interests include control of necrotrophic fungal pathogens of vegetable crops.
Mr Dimitrios Katsantonis, a postgraduate student at the University of Reading, researching the molecular biology of Fusarium and damping-off pathogens in vegetable and ornamental crops.
Mrs Mansureh Keshavarzi a postgraduate student at Wye College, researching the biochemistry of Xanthomonas pathogens in pepper.
Dr Irene Koomen, from ADAS, Wye, whose interests include fungal pathogens of fruit.
Prof. Nimal S Kumar, from the University of Peradeniya, Sri Lanka, whose interests include biologically active natural products.
Dr Stuart Lane, from the Department of Biological Sciences at the University of Plymouth
Mr Christoph Loewer, a postgraduate student at Justus-Leibig University, Germany.
Miss Ruth L Mann, a postgraduate student at Harper Adams Agricultural College,
Miss Orla McEnery, a postgraduate student at University College Dublin, working on net blotch and Fusarium resistance in cereals.
Miss Rosalind C McHugh, a postgraduate student at the University of Aberdeen, researching control of Botrytis sp. in lettuce and tomato.
Miss Sarah R McLusky, a postgraduate student at Wye College, researching Botrytis resistance in onions.
Dr Peter Mercer, from Queens University, Belfast.
Heidi Mitchell, from the Plant Cell Biology Group at the Australian National University, Canberra.
Dr Venkataramappa Muniyappa, University of Agricultural Sciences, Bangalore, India, whose interests include the molecular biology of geminiviruses.
Miss Henrietta Myburg, a postgraduate student at the University of the Orange Free State, South Africa, working on the molecular biology of Cryphonectria cubensis.
Dr Mariana Nakova, at the Higher Institute of Agriculture in Plovdiv, Bulgaria, whose interests include the epidemiology of fungal pathogens.
Mr Georgios Neophytou, of Hadlow College, Kent, whose interests include plant pathogen diagnostics.
Maria Nihlgard, from Novartis Seeds AB, Sweden.
Claudia Olivier, a postgraduate student at Cornell University, USA, working on necrotrophic fungal pathogens of vegetable crops.
Ms Alexandra Ott, a postgraduate student at the University of the West of England, whose interests include downy mildew.
Miss Claire-Louise Palmer, a postgraduate student at IACR-Long Ashton, researching plant fungal pathogens and fungicides.
Dr Barbara W Pennypacker, from Penn State University, USA, whose interests include physiology of vascular pathogens of soybeans and alfalfa.
Mr Andrew I Purvis, a postgraduate student from UCNW, Bangor, working on molecular genetics of fungal pathogens.
Miss Kathryn E Perry, a postgraduate student at SAC Edinburgh, researching molecular biology of fungal pathogens.
Dr Carmen Raikes, from the University of Georgia, USA, whose interests include diagnostics for necrotrophic pathogens of cereals.
Dr G P Rao, working on diagnostics for crop pathogens in Delhi, India
Miss Sarah L Rawlings, a postgraduate student at the University of Birmingham, working on the molecular biology of Colleotrichium in Phaseolus.
Mr Patrick J Reid, a postgraduate student at the University of Nottingham, researching Colletotrichium molecular biology.
Dr Frederic Revers, a virologist at the John Innes Centre.
Dr Christopher J Ridout, who works on the molecular biology of cereal powdery mildew at the John Innes Centre.
Miss Kajsa Rise, a postgraduate student from IACR-Long Ashton.
Miss Jolanda Roux, a postgraduate student from the University of the Orange Free State, South Africa, working on tree pathology.
Mr Ioannis Saligkarias, a postgraduate student at the University of Manchester, whose interests include necrotrophic fungal pathogens of vegetable crops.
Miss Anna C Salter, a postgraduate student at the University of Reading, researching the epidemiology of Botrytis sp. in ornamental plants.
Dr Paul Schulze-Lefert, a molecular biologist at the John Innes Centre, whose interests include mildew and rust pathogens of cereals.
Mr Reuben A Sessa, a postgraduate student at Wye College researching the molecular biology of necrotrophic pathogens of lettuce.
Dr Duncan R Simpson, a molecular biologist at the John Innes Centre, Norwich, working on fungal pathogens of cereals.
Mr Gurjeet Singh, a postgraduate student at Cambridge University.
Dr Premjit J Singh, of the Punjab Agricultural University, India, whose interests include post harvest fungal pathology.
Mr Bernard Slippers, a postgraduate student at the University of the Orange Free State, South Africa, researching the molecular biology of forest pathogens.
Mr Henk Smith, a postgraduate student at the University of the Orange Free State, South Africa, whose interests include the ecology of vascular pathogens of trees.
Dr Julian Smith, from the International Mycological Institute.
Miss Nicola J Spice, a postgraduate student at Nottingham Trent University
Mr Marciel J Stadnik, a postgraduate student at Universitat Hohenheim, Germany, whose interests include systemic induced resistance in cereals.
Miss Emma T Steenkamp, a postgraduate student at the University of the Orange Free State, working on the molecular biology of Fusarium pathogens of trees.
Dr Conrad Stevens, from Wye College, working on the molecular biology of Pseudomonas pathogens of Phaseolus sp.
Dr Rebecca Stratford, a molecular biologist at PBI Cambridge.
Mr Cristian M Tamblyn, a postgraduate student in Bristol.
Miss S E Thomas from the International Mycological Institute.
Mr George Tsiamis, a postgraduate student from Wye College, researching the molecular biology of Pseudomonas sp. pathogens in beans.
Miss Jane Tuohy, a postgraduate student at University College Dublin, researching necrotrophic pathogens of cereals.
Tom van den Boogaart, a postgraduate student at the John Innes Centre, researching viral molecular biology.
Mr Nicolaas A Van Der Merwe, a postgraduate student at the University of the Orange Free State, working on molecular biology of fungal pathogens of trees.
Dr Jeanmarie Verchot, a molecular biologist at the Sainsbury Laboratory, Norwich.
Edward J Walsh who is at University College Dublin.
Ms Josie Williams, a postgraduate student at the University of Bath, researching into the molecular biology of necrotrophic pathogens of mushrooms.
Prof. Michael J Wingfield, from the University of the Orange Free State, South Africa, whose interests include molecular biology of forest fungal pathogens.
Miss Sally Wither, a postgraduate student at Cambridge University.
Ms Corli Witthuhn, a postgraduate student at the University of the Orange Free State, South Africa, working on molecular genetics of forest pathogens.
Miss Rebecca A Wyand, a postgraduate student at the John Innes Centre, researching the molecular biology of cereal powdery mildew.
REFEREES, PLEASE PLAY THE GAME!
Editors on the Editorial Board of Plant Pathology are bringing to my attention, more and more frequently, the difficulty they are having in obtaining responses from referees. Unfortunately, when referees delay returning papers, this results in dissatisfaction on the part of authors and reflects badly on the journal.
I recognise the difficulties faced by referees, when unsolicited papers land on their desks without warning, irrespective of any commitments they may have at the time. (I raised the question in Council of whether referees should be contacted before being sent papers, and the general view was that this would provide too much opportunity for refusal). However, the system we use to publish papers depends absolutely on the performance of competent referees.
I know that there is little reward for referees. There is only one argument that I can advance to encourage prompt and careful responses from them. Virtually all referees will, themselves, be authors of papers submitted to a refereed journal. They will then be dependent on fair and prompt appraisal of their work prior to its publication. If referees perform slowly, or in some notorious instances not at all, they should not complain if they suffer the same fate when they submit their own papers.
On rare occasions, if a person selected as referee knows they cannot do the work, they should return the paper rapidly to the editor. This should not happen frequently because scientists should accept that it is an inevitable responsibility to referee papers. However, in practice, referees occasionally neither do the work or return the paper. Although fortunately rare, this cannot be considered an acceptable option.
Please help us to maintain the standards and attractiveness to authors of our journal, the lifeblood of our society, by taking the task of refereeing papers very seriously when, however infuriatingly, you are asked to.
Rhizoctonia fungi and the mycoparasite Verticillium biguttatum
The mycoparasite, Verticillium biguttatum, has potential for biological control of plant pathogenic, binucleate Rhizoctonia. Consistent and effective control can be achieved by a thorough understanding of the modes of action involved. As a first step, in vitro tests can be applied. Provided the limitations of these tests are realised, information on the potential of antagonists to parasitise hosts, produce antibiotics and compete for nutrients can be obtained quickly.
In vitro tests were set up to assess the ability of two isolates of V. biguttatum, M73 and M92, to infect and suppress the growth of two isolates of binucleate Rhizoctonia, D1 and I48. A small-scale glasshouse trial with Calluna vulgaris cv Cuprea was also conducted to assess the biocontrol activity of the antago nist against the binucleate Rhizoctonia spp.
Isolates of V. biguttatum were assessed for antibiotic production. On potato dextrose agar (PDA), M92 and M73 inhibited the growth of both isolates of the pathogen, indicating the production of volatile and non-volatile antibiotics. M92 gave greater inhibition than M73. On distilled water agar (DWA), both isolates of the antagonist stimulated growth of the pathogen. In colony interaction tests on agar, both isolates of the pathogen were overgrown by V. biguttatum on both high (PDA) and low (DWA) nutrient agar.
Under low nutrient conditions, infection of hyphae of the two pathogen isolates was confirmed using light microscopy. Both isolates of V. biguttatum induced granulation in the pathogen hyphae and produced adpressed growth and hook-like side branches. Coiling of V. biguttatum around the hyphae was also observed. Isolate M92 infected and overgrew colonies of the pathogen faster than M73 on precolonised PDA from both mycelial and conidial inoculum. In the glasshouse biological control bioassay, only M92 significantly reduced infection of C. vulgaris by binucleate Rhizoctonia.
During my ten week work experience at the Scottish Agricultural College, Auchincruive, I also gained basic training and experience in diagnosing diseases on plants submitted to the Department's Crop Health Centre. I would like to thank Dr Mark McQuilken for his patience and supervision.
Suzanne F L Chow
Ascochyta complex on pea
Fungi of the `Ascochyta Complex' (Ascochyta pisi, Mycosphaerella pinodes and Phoma medicaginis var. pinodella) reduce the yield of cultivated pea, Pisum sativum, following leaf or stem base infection. Breeding for resistance is probably the best long-term strategy for control of these diseases.
My project involved investigation of resistance in pea to an isolate (Ap-3) of Ascochyta pisi, British Pathotype 3, using the mapping population constructed by Dr Noel Ellis at the John Innes Centre. The population has been genetically mapped in detail, making the search for disease resistance genes possible. The aim of my project was to map the resistance to Ap-3 in pea.
A resistant line (JI 15) and a susceptible line (JI 399) were tested for resistance to Ap-3 and different reactions to the pathogen were found. The resistant phenotype presented as either a hypersensitive reaction or no reaction at all, while the susceptible phenotype showed typical necrotic lesions, 3-4mm in diameter. Microscopically, the resistant phenotype showed longer germ tubes with fewer appressoria and penetrations than the susceptible type. A new method of inoculating leaves with spores was developed during this project to aid the microscopy studies.
79 recombinant inbred lines at the F12 generation from a cross between JI 15 and JI 399 were then tested for resistance to Ap-3. A 1:1 ratio of resistance to susceptibility was found among the inbred lines, indicating resistance to be monogenic. After analysis at the John Innes Centre, the gene for resistance was tentatively mapped to linkage group III and found to be weakly associated with a terminal marker, Tps1/11.
During the ten week studentship I learned many laboratory techniques, how to plan and carry out experiments and how to interpret results. I wish to thank Dr Lewis for his guidance and encouragement and the BSPP for giving me this opportunity.
Fungicide resistance in wheat powdery mildew
My project in Dr James Brown's lab at the John Innes Centre in Norwich involved determining to what degree Erysiphe graminis f.sp. tritici has become resistant to fungicides since their introduction. I carried out several experiments using triazole and morpholine-like fungicides in which I tested the difference in resistance between control isolates which were about 15 years old and isolates collected in Norfolk during 1997. Using increasing doses of fungicide on wheat seedlings, I could assess how resistant each isolate was.
Most of the fungicides used in this project were applied to ten day old wheat seedlings as sprays, including the triazoles cypro-conazole, epoxiconazole, propi-conazole and tebuconazole and the morpholine-like fungicides fenpropidin, fenpropi-morph and tridemorph. Another triazole, triadimenol, was applied as a seed treatment. Segments of the sprayed wheat were inoculated with one of the collection of about 80 mildew isolates. Wheat segments were then left for a further 8 days at 15oC for the mildew to develop on the leaf surface. Leaf segments sprayed with ten different doses of each fungicide were used to determine isolates' resistances and this gave a clear indication of each isolate's responses to the various fungicides.
The results showed a clear difference between the older isolates and those collected recently, with the older isolates being more sensitive to all the fungicides. My project has provided a firm basis to investigate cross resistance within and between the two main groups of wheat mildew fungicides. In the future, results from this project will be compared with previously obtained results on fungicide resistance in barley powdery mildew, Erysiphe graminis f.sp. hordei.
The BSPP undergraduate bursary I received for ten weeks over the summer vacation gave me the chance to see how life in a lab compared to the practical experience I have obtained during my degree. The research I carried out was interesting and I drew motivation from the interest others showed in my results. I was able to show my results demonstrating resistance to epoxiconazole to a group from the National Farmers Union who visited the institute at one point during my project. All seemed interested in the work I had done and eager to hear about future tests. I am continuing to study aspects of plant pathology in two modules at the University of East Anglia.
Directional growth of Peronospora viciae in pea leaves
The aim of my bursary was to assess the pattern of tissue colonisation in millet downy mildew, as part of a programme to survey downy mildew infections of hosts with different vein types and phloem loading mechanisms. There were problems, however, with obtaining sporangia of this pathogen. Although many oospore-inoculated plants showed symptoms, microscopic examination of leaf sections showed infrequent occurrence of intercellular hyphae and a lack of sporangiophores. So I learned first hand how difficult obligate biotrophs are to work with!
Instead, therefore, my work focussed on pea downy mildew, of which a reliable source of sporangia was available. Leaves from the first and second nodes of 10 day old plants of Pisum sativum cv Krupp Pelushka were inoculated by brushing their surface to flatten waxes and adding a 10ml droplet of 1x104 spores ml-1 to the upper surface on both sides of the midrib. Plants were incubated for 48 h, leaves were cleared and stained, then observed by bright field and epifluorescence microscopy. The directional growth of germ tubes in relation to stomata and veins, and of intercellular hyphae in relation to veins, were recorded.
There was some evidence for germ tube growth towards stomata, but not towards veins. In contrast, the growth of infection hyphae was directed towards the nearest veins, and especially vein endings, immediately after penetration. The orientation of hyphal tips 48 h after inoculation was random.
It is hoped that this work will form part of a publication to be submitted to Plant Pathology and contribute towards a poster at the ICPP 98. I would like to thank the BSPP for the valuable experience. I would also like to thank Dr Peter Spencer-Phillips and staff and research students in the Faculty of Applied Sciences at the University of the West of England for being extremely friendly and helpful.
Identification of fungi causing heart-rot in Acacia mangium
The aim of my project was to identify the primary pathogens of heart rot occurring in Acacia mangium. I was supervised by Dr Carlo Leifert (University of
Aberdeen) and also worked with Dr Stephen Woodward (Aberdeen) and Mahmud Sudin, Forest Research Centre, Sabah, Malaysia, Twelve months previously,
25 healthy Acacia mangium had been artificially inoculated with basidio-mycetes, isolated from naturally diseased lesions. This summer, the virulence of each
of those isolates was measured by assessing the extent of degradation at each inoculation point. The isolates of fungi from inoculated points fulfilled Koch's
postulates for the identification of a primary
The 25 sample trees were clearly marked within an experimental plantation. Once the tree vigour had been recorded, the sample trees were felled. The lower 2 m of the log was then cut longitudinally and dissected through each inoculation point, giving 50 cm logs with half an infection court at one or both ends.
Using aseptic techniques, chips were taken from each lesion and placed onto basidiomycete selective medium (BSM). From those original cultures, each individual colony was subcultured onto a separate BSM slope. There were significant differences in lesion size between fungal inocula and it is believed the virulence of the fungi varied accordingly.
We are currently identifying fungi re-isolated from heart rot lesions in an attempt to identify the primary pathogens involved, thus allowing subsequent studies on the succession of wood decay and non-decay fungi present in heart rot lesions, and the relationship between population density and lignolytic activity of the primary pathogens identified in this study.
I am grateful for the support of Rahim HJ Ahmad Nawi and Chen Thau En from the FRC Pathology Department in Sepilok. Tree felling and dissecting was achieved at great speed by James Gasan.
Antagonism of fungi from composts to soilborne pathogens
Previous work at Exeter University has established that significant disease suppression can occur where commercially produced recycled organic matter (ROM) composts are used, compared to John Innes proprietary products. The mechanisms for this effect are presently unclear. It is known that sterilization and aging of the ROM compost affects disease suppressive qualities, implying a biological effect. My BSPP undergraduate bursary enabled me to research the microbiology of ROM composts of different ages. Because of the limited time available it was decided to restrict investigations into antagonism to isolated fungi only.
A range of methods were used to investigate the microbial communities. Concentrations of bacteria and fungi were estimated by dilution plating and yielded counts
of colony forming units of 104 fungi and 108 bacteria per gram dry weight. No significant difference could be ascertained in the concentrations in different composts.
Over two hundred fungi were isolated and subcultured from dilution plates but only 15 species were later discerned. These were screened for antagonism towards three pathogens, Sclerotium cepivorum, Phytophthora fragariae and Verticillium albo-atrum. The screening revealed several species with marked antagonism towards the pathogens. There was variation in susceptibility, with different antagonists being more or less effective with different pathogens. The most effective antagonists were found to be: Trichoderma viride, species in the Aspergillus fumigatus series, and a Penicillium species provisionally recorded as P. canescens.
Various methods were used to attempt to establish that the isolated antagonists were active biological components within the composts and not simply activated propagules. Direct plating and immersion tube isolation methods produced results that indicated T. viride is a particularly active component in the tested composts. This species was also the most effective antagonist. In the time available I was not able to quantify the relative concentrations of antagonist species satisfactorily.
Thanks to the considerable efforts of Dr Dennis Pitt (University of Exeter) and the valued support of BSPP Council, I have had an excellent opportunity to experience laboratory research in an exciting and challenging field. For this, I am sincerely grateful.
Resistance responses of Scots pine to Endocronartium pini
Endocronartium pini causes a rust disease of Scots pine and is a serious pathogen in northeast Scotland and Thetford Forest. At the Department of Forestry, University of Aberdeen, I was given the opportunity to investigate if the measurement of phenylalanine ammonia lyase (PAL) activity and observations of fungal growth under the electron microscope could be used to determine different levels of resistance to this pathogen. The project investigated variations in these factors within and between different provenances of Scots pine.
Seedlings of Scots pine from two provenances were grown aseptically on distilled water agar for 28 days, then inoculated in vitro with E. pini aeciospores. At 48h intervals over a 16 day period, tissues were ground in liquid N2 and extracted in borate buffer. PAL activity was estimated in the supernatant by measuring the release of trans-cinnamic acid from phenylalanine. Additional plant material was prepared for electron microscopy (EM), so that PAL activity in the tissues might be related to hyphal penetration and the development of defined barriers.
Difficulties arose with the collection of aeciospores of E. pini. The variable weather conditions in N.E. Scotland in spring 1997 reduced the amount of sporulation, and only one tree with abundant aeciospores was found in Culbin forest. Further aeciospores, for in vitro use, were obtained from Risto Kasanen of the University of Helsinki. The sterilisation of Scots pine seed also proved problematic: seed from several provenances contained contaminants which were not killed using standard procedures. Soaking the seed for a longer period in H2O2 reduced the number of contaminants.
PAL activity between replicates was very variable, probably reflecting the level of heterogeneity in the seed batches, and the diluting effects of host tissues not exposed to the pathogen. However, activity increased during the time course of the experiment, with a peak 8 days after inoculation. The variability of the results made it impossible to evaluate PAL activity as a marker for resistance to E. pini. Future work should concentrate on the development of systems using clonal material, to reduce variability due to genetic variations in the host.
Scanning EM revealed the importance of needle surface topography for the growth of E. pini germ tubes, with most growth along the leaf axis. Further work towards my Honours thesis is being carried out on the formation of resistance barriers inside host tissues, using transmission EM. I would like to thank the BSPP for this opportunity, and Dr Steve Woodward, Billy Bodles and Janis Brodie for their encouragement.
Detection of tomato and barley powdery mildew
The BSPP studentship provided me with the opportunity to undertake a summer project in the laboratory of Dr Sarah Gurr, Department of Plant Sciences, Oxford University, studying the newly described powdery mildew which infects glasshouse-grown tomatoes. Powdery mildews infect many varieties of plants, including numerous economically important, cultivated plants. They are so successful as pathogens, being continually prevalent among crop plants and ornamentals, that they bring about substantial agricultural and financial losses every year. As well as tomato mildew, I also studied the better known mildew which infects barley, Erysiphe graminis. For both mildews, the aims were to develop a new detection protocol based on the use of monoclonal antibodies.
The plate-trapped antigen ELISA method of Dewey et al. (1989) was used to screen monoclonal antibodies for those which recognised the mildews in question. Out of 45 antibodies screened for recognition of tomato mildew, seven showed positive recognition of the fungus without cross-reaction, while five out of 56 antibodies showed positive recognition of barley mildew without cross-reaction. These antibodies may have potential for detecting the respective mildews in planta. The ELISA techniques used in the study are particularly important because portable ELISAs, such as the dip-stick and dot-blot assays, would allow these useful reactions to be carried out in situ.
I welcomed the experience of working independently in the lab, using my own initative to solve the problems posed by my area of study. It was a refreshing change from my undergraduate course in Biological Sciences where practical sessions are rushed through in a few hours. I enjoyed the more thorough and methodical approach required for research work, as well as the freedom to follow up my own ideas and interests.