BSPP News 30 Spring 1997 - Online EditionThe Newsletter of the British Society for Plant Pathology
Number 30, Spring 1997
International Union of Microbiological Societies (IUMS)Congresses '96
9th International Conference on Plant Pathogenic Bacteria
9th European and Mediterranean Cereal Rusts and PowderyMildews Conference
Diagnosis and Identification of Plant Pathogens
Spectroscopy & Optical Techniques in Animal andPlant Biology
The Brighton Conference - Pests & Diseases
8th Annual Congress of the Postgraduate Institute ofAgriculture, Sri Lanka
Unlocking the Future: Information Technology in PlantPathology
International Union of Microbiological Societies (IUMS)Congresses '96
incorporating the International Committee of Systematic Bacteriology (ICSB)Meeting
18-23 August 1996
The International Congress of Microbiology was jointly run by the MycologyDivision and the Bacteriology and Applied Microbiology Division of IUMS,encompassing plenary, round-table invited papers and poster sessions. A posterentitled "The comparative use of genomic fingerprinting techniques for thecharacterisation of Ralstonia (Pseudomonas) solanacearum" (J JSmith, M Holderness, G Saddler) was presented. In addition, as the current BSPPrepresentative on the ICSB, I was able to attend ICSB sessions runningconcurrently with the IUMS congress.
The ICSB meeting was split over three sessions and was dominated bydiscussions of the Draft BioCode: The Prospective international Rules forthe Scientific Names of Organisms (Ed. D L Hawksworth - copies availablefrom G Saddler, IMI). Other areas for discussion included the publication of theInternationalJournal of Systematic Bacteriol ogy (IJSB) the use of bacterial patentstrains as type material, the status of partially described taxa (Candidatus),the need for minimal standards and the use of dead specimens as type material.
a) BioCode - The new Code attemps to harmonize the majorbionomenclatural codes (bacteriological), botanical and zoological, with specialprovision for viruses and cultivated plants) and governs the formation andchoice of scientific names but not the definition of the taxa themselves.Existing codes of nomenclature will continue to operate for names of the past,but after the implentation date (proposed for 1 January 2000), the new Code willoperate for names published after this date. The production of this highlydetailed discussion document invites comment from interested parties prior to 31December 1996 and these should be addressed either directly to David Hawksworth,IMI or through the ICSB's representatives on the International Committee onBionomenclature (ICB; Peter Sneath, Leicester University, UK & BrianTindall, DSMZ, Germany) for amalgamation into the final document.
During this meeting the new Code was discussed at some length and a largenum,ber of points of clarification, and amendments will be forwarded to ICSB'srepresentatives on the ICB. Clearly, established members of the ICSB are happywith the Bacteriological Code as it stands, and remain to be convinced of theworth of this initiative. Turning to specific issues, the new Code will notcover taxa below the rank of subspecies and therefore will not directly affectthe working of the ISPP Sub-committee for Taxonomy of Plant Pathogenic Bacteriaand their published guidelines for the naming of infraspecific taxa such aspathovars.
b) IJSB - The journal is currently published quarterly onbehalf of ICSB by the American Society for Microbiology (ASM) and has acirculation of approximately 2000. ICSB was recently informed by ASM that IJSBis operating at a loss and therefore package of measures to improve thefinancial status are being examined which include the introduction of pagecharges (not favoured by the ICSB), increasing the subscription rate or movingthe journal to an alternative publisher.
c) Patent strains - It is widely recognised that access totype material is vital for making valid comparisons or identifications ofbacteria, and that this material should be available from "recognisedculture collections". In this regard, a problem arises when type materialis also the subject of a pending patent and therefore not freely available. TheICSB has therefore endorsed the view that the name should not be validated(published in IJSB) until the patent is awardfed and the material becomesavailable from a recognised culture collection.
d) Candidatus - The ICSB endorsed the recent proposal toadopt a new procaryotic category, Candidatus, to cover taxa that canonly be described in limited terms, for example, sequence information from auncultivable procaryotic organism (Murray & Stackebrandt, 1995, Taxonomicnote: Implemention of the provisional status Candidatus for incompletelydescribed procaryotes, IJSB, 45, 186-187).
At present the ICSB has stated that "the integrated use of phylogeneticand phenotypic characteristics, or polyphasic taxonomy, is necessary for thedelineation of taxa at all levels from kingdom to genus" and thus does notencourage microbiologists to base a taxonomic description solely on phylogeneticplacement inferred from comparison of nucleotide sequences. Currently, the worthof sequence information is almost universally accepted in phylogentic andsystematic studies and this new proposal will grant the status Candidatusonly to uncultivable procaryotic taxa for which relatedness has been determinedand authenticated by in situ probing.
This designation is not a "rank" but a "status" and assuch is not recognised by the Bacteriological Code. It is possible that thisproposal may have implications for the nomenclature of uncultivable plantpathogens such as phytoplasmas (mycoplasma-like organisms).
e) Minimal standards - As stipulated in the BacteriologicalCode "Before publication of the name and description of a new species, theexamination and description should conform at least to the minimal standards (ifavailable) required for the relevant bacterial taxon". Unfortunately fewminimal standards have been produced for bacterial genera. Therefore theproduction of a "Taxonomic Note" was encouraged to give guidance whereminimal standards did not exist.
This publication would list general principles such as: descriptions shouldbe based on as many strains as possible; descriptions should incorporatecharacteristics derived from a variety of techniques, which should includegenotypic data; descriptions should encompass comparative studies with relatedtaxa; illustrations should be included where appropriate; details should begiven of ecological data and where the strains/material are deposited. Theproduction of this "Taxonomic Note" was endorsed and should serve asthe bench mark for future work, especially when dealing with genera for which noformal minimal standards exist.
f) Dead bacterial specimens - Bacteriology has traditionallyrelied heavily on living cultures in culture collections and has shown littleinterest in dead preserved material. Technical advances in molecular biologyhave greatly increased the potential of dead preserved material. In this regard,nucleic acid sequences can be obtained from dried material by the use of PCR.Although the Bacteriological Code has made provision for preserved materials tobe the types of uncultivable bacteria, this has seldom been used. The presentsuggestion was welcome as dried specimens are cheap to prepare and maintain andoffer the only method for preserving uncultivable microorganisms.
g) Other business - In addition, I was able to bring theICSB up-to-date on some recent work by the ISPP sub-committee for Taxonomy ofPlant Pathogenic Bacteria, namely our recent publication of a complete listingof all plant pathogenic bacteria names currently in use at 31 December 1995(Young et al., 1996. Names of Plant Pathogenic Baveria 1864-1995. Reviewof Plant Pathology 75, 721-763). The ICSB also welcomed thesub-committee's intention to set-up WWW access to this material with a plan forannual updates.
Sessions of particular interest were related to systematics and ecology,bioremediation and waste water treatment, biological control and the release ofgenetically modified organisms. In all of these sessions it is apparent that thetrend is towards the increasing use of molecular methods. It was evident thatthese methodologies are dominant throughout all branches microbiology and willcontinue to be so in the foreseeable future.
Prof Erko Stackebrandt and his group at the German culture collection (DSMZ)have shown that within certain bacterial strains macroheterogenity in the 16SrDNA sequence is evident. In this regard, it is possible to detect 3 differenttypes of sequence, the basis sequence, and/or with one or two introns(previously it was thought that only one sequence type was present in a strain).What is also interesting is that when the rRNA is sequenced directly only onetype is found, with no insertions. At present there are no hypotheses as to whythis should occur, but possibly some mechanism of post-transcript ionalmodification is operating, which may have implications for the use of rDNA andits role in inferring phylogeny of bacteria.
Professor Karl-Heinz Schleifer (University of Munich) has perfected a rangeof in situ hybridisation techniques and applied these to studies ofactivated sludge treatments. From these studies, he has shown clearly that theuse of selective media to study microbial diversity in such an environment canproduce highly misleading results. Of three standard media compared againstmolecular methods, none were able to recover more than 20% of the prokaryoticdiversity from this environment. In addition, each media selectively enrichedfor a different sub-set of the community, severely compromising the ability toassess diversity using traditional bacteriological methods.
Dr Gary Sayler (University of Tennessee) chaired a lively session on currentstrategies for the release of genetically modified microorganisms (GMM's).Clearly there is a growing divergence on this issue between Europe and NorthAmerica. In the US it is becoming easier to gain authorisation for such work(around 600 licences were granted in 1995) and genetically modified vegetablesor those containing GMM's are currently sold in the shops. It would appear thatthe Europeans are working under much tighter constraints probably as a result ofconsumer confidence (or the lack of it in the field!). The point was made thatthe recent confusion caused within the UK over the BSE crisis could have aknock-on effect in areas such as the use of GMM's, particular in food cropproduction.
Dr Stephen Farrand (University of Illinois) gave an interesting talk on theuse of Agrobacterium tumefaciens strain K84 for the biocontrol of crowngall. Established thinking holds that K84 controls disease because it producedagarocin 84, it can only control agarocin 84 sensitive strains and strains ofK84 which lose the ability to produce agarocin 84 also lose the ability tocontrol. Recent findings would tend to challenge this view as K84 used underfield conditions can control agarocin 84 resistant strains. The growing beliefis that biocontrol is polygenic and may involve the production of othercompounds such as agarocin 434 or sidero phores or simply because K84 is betterat colonisation and survival on the host than other strains of the species.
International Mycological Institute, Egham
9th International Conference on Plant PathogenicBacteria
University of Madras, India
26-29 August 1996
The 9th International Conference on Plant Pathogenic Bacteria, hosted by theCentre of Advanced Study in Botany, University of Madras, was held at the IndianBank Staff Training Centre, Madras, India. Around 95 delegates attended,represented 26 countries, including several eastern and western European, SouthAmerican and African countries. The representation of India was quite remarkablefor the number of delegates, presentations (48), and students present.
There were 121 oral and 54 poster presentations organised into 11 sessions.Sessions I, II, IIIA, and IVA dealt with recent approaches in the diagnosis andcharacterisation of phytopathogenic bacteria; sessions III and IV dealt withphysiology, biochemistry, and molecular biology; sessions V and VI dealt withepidemiology; sessions VA and VIA dealt with disease management & commercialexploitation; session VII dealt with plant resistance mechanisms & hostspecificity.
On the first day, after the inaugural function in the presence of severalstage government representatives, the conference began with a key note addressby Dr Klement (Hungary) entitled "Interaction between the early inducedresistance (EIR) and the hypersensitive response (HR)". This was followedby a second key note address from Dr Rudolph (Germany) about the role ofpolysaccharides in disease development.
The first and second sessions presented several techniques for thecharacterisation and identification of Xanthomonads and Pseudo monads. Aninsight to the genetic diversity of Ralstonia solaneacerum, Erwiniaamyhlovora and Pseudomonas syringae was presented in these sessions.Dr Lemattre (France) presented a particularly interesting paper about the use ofribotyping as a tool to characterise bacteria. The last paper of this day wasmine entitled "Variation among populations of Pseudomonas syringaepvs. morsprunorum and syringae from sweet and wild cherry treesdetermined by carbon-source profiles and REP-PCR" (Luz & Shaw, theUniversity of Reading, UK). The day concluded with an evening of classicalIndian dancing performed by two amateurs who introduced us to the beauty of theBharath Natyam dances. These dances, performed by women, usually tell events inLord Krishna's life. The superb dinner that followed was full of the Tamil Nadudelicacies and considered by the foreigner delegates to be good but rather hot.
The second day of the conference started with a brilliant key note addressby Dr Lemattre entitled "Recent advances in diagnosis of bacterialdiseases: new tools but for what purposes?". An exhaustive exposition ofthe methods currently available to identify and characterise bacteria was madesummarising also the work that has been done at INRA, Versailles. Afterwards Iattended the parallel session continuing the subject of the previous day, "Recentapproaches in the diagnosis and characterisation of phytopathogenic bacteria".Different techniques were reviewed liked ELISA (Rajwsahawari, India),immunofluorescence colony staining (van der Wolf, Netherlands), fatty acidprofiles (Parente, UK), and macro- restriction of genomic DNA resolved bypulse-field gel electrophoresis (Smith, UK).
After lunch we were given two more lectures from Dr Sridhar (India) - "MolecularCharacterisation of bacterial blight pathogen of rice and its utility fordeveloping durably resistant varieties", and Dr Reddy (India) - "Phytosanitarymeasures against the introduction and spread of phytopathogenic bacteria".
After these two lectures, I opted for the parallel sessions about diseasemanagement & commercial exploitation. An interesting paper in this sessionwas about copper resistance in Xanthomonas campestris pv. citri(Canteros, Argentina). The day finished with another splended dinner but withnot much time to have a proper look at the posters.
The third day was dedicated to visits to three beautiful temples. The first,Sri Ekambaranathar in Kanchipuram, was started by the Pallava kings in the 7thcentury. In one of the enclosures there is a very old mango tree, claimed to be3500 years old, with four main branches representing the four Vedas (divineknowledge). The fruit of each of the four branches is said to have a differenttaste. Everyone was very impressed by the beauty and huge size of this temple.
The other two temples were at Mahabalipuram, built by the same rulers in thelate 7th century. They are carved directly from rock; the one on the beach,called the Shore Temple, is particularly beautiful and has World Heritagestatus. The day finished with a superb show of classical, Indian film, and breakdances, followed by an opulent dinner served on banana leaves eaten in thetraditional way (fingers!).
The last day of the conference started with a key note address by Dr Vuurde(Netherlands) entitled, ?Detection and ecology of phytopathogenic bacteria andhealth promoting bacteria at IPO, DLO'. This was a very well organised andcomplete exposition of the serological methods available and under investigationto detect and identify plant pathogenic bacteria.
Just after lunch we had the last lecture by the chairman of the meeting, DrMahadevan (India), about ?Detoxification mechanisms in phytopathogenicbacteria'. After this address Dr Saddler (UK) presented the most recent changesin the names of phytopathogenic bacteria suggested by the Sub-Committee of PlantPathogenic Bacteria of the International Society for Plant Pathology. The restof the afternoon was specially dedicated to a valedictory function in honour ofProf Rangaswami, where around 10 speeches (of at least 15 minutes each!) weregiven by former colleagues, PhD students, and friends. The Conference finishedwith another superb cultural programme of religious classical dances and anotherdinner.
I wish to acknowledge the travel grant awarded by BSPP that partly financedby attendance at the Conference and Praxis XXI (EU programme) that covered therest of my expenses.
Joao Pedro Luz
University of Reading
9th European and Mediterranean Cereal Rusts andPowdery Mildews Conference
Lunteren, The Netherlands
2-6 September 1996
The setting for the conference was the middle of a wood in a picturesquepart of Holland at a congress centre called "De Blije Werelt" - "TheCheerful World". Over 160 scientists attended to present or discuss theirwork towards the understanding and control of cereal rusts and powdery mildews.The seminars were given over 4 days and over 80 posters were on displaythroughout the conference. The poster sessions and mealtimes gave participantsample opportunity to mingle and meet each other while enjoying the generousspread of food.
Although billed as a European and Mediterranean conference, this conferencedrew participants from all continents except Antarctica (where, we gather,sowing strategies have meant that neither rusts nor mildew are considered to bea problem). Most of the participants from outside of Europe were interested inrusts, so giving a global perspective to the problem of rust control. Incontrast, interest in mildew was confined to Europe and its environs - a lack ofdiversity that was perhaps countered by a greater diversity of approaches takenin the study of mildew.
The opening address was given by Bob McIntosh, from Australia. He recalledthe developments made in cereal rust genetics since his career began 36 yearsago; from the gene to gene hypothesis, to the achievement of durable resistanceand the cloning of resistance genes. Although progress had been great, he calledout attention to the constant challenge posed by the continual evolution of thepathogens. He stressed the need for investment, the importance near-isogeniclines, and a need to "get to know gene interactions".
There were 4 broad themes to the conference, and the first, "Molecularand Physiological Aspects of Host Pathogen Interactions" plunged usstraight in at the cutting edge of research towards an understanding of themechanisms involved in a pathogenic interaction. Henriette Giese (Riso, Denmark)started off by gazing into the crystal ball and predicting that soon atransformation system will be developed in Erysiphe graminis f. sp.hordeifor direct assessment of the functions of the genes involved in infection.Experiments with biolistics already show GUS expression in conidia after hittingbasal cells with DNA. Advances have been made with finding molecular markers andmap based cloning and it will not be long before these genes will be isolated.
Other talks covered the induction of defence genes, systemic resistance (BBarna, Budapest, Hungary), and genetics and mechanisms of mlo resistance (JannieAtzema, Swiss Federal Institute of Technology, Switzerland; Michael Lyngkjær,Risø, Denmark)
One approach that has been taken towards cloning a resistance gene wasdescribed by Beat Keller (Reckenholz, Switzerland). Two plant resistance geneswhich have already been cloned are protein kinases. Using conserved sequences inthe resistance genes, the Swiss group probed Thatcher near isogenic lines andsidentified a DNA band that only appeared in the line with Lr10. Furtheranalysis supported the view that it could be Lr10. The gene has beensequenced, and it looks like a receptor. Although the gene product is the rightshape, they were yet to show that the gene is involved in resistance, as opposedto just being "next door" to one.
"Population Diversity and Dynamics" was the second theme, whichbegan with a keynote presentation from Jan Parlevliet (Wageningen, TheNetherlands). Breeding for resistance leads to rapid changes in host populationsthus promoting the evolution of complex races of pathogens. He highlighted theimportant factors promoting variation in asexually reproducing pathogens andconcluded that reproduction system is not a major factor affecting theaccumulation of virulences. He ended with the outlook that, despite the largenumber of resistance genes which have become ineffective, the remaining ones canbe used more effectively in combinations.
Again in this theme, molecular biology reared its head, with severalpresentations using molecular markers to subdivide populations. Les Szabo(Minnesota, USA) cast the leaf rust phylogenies into doubt with a phylogeneticanalysis of leaf rusts from North America and the Middle East, and showed thatthe main phylogenetic division was between old and new world rusts. Thissuggests that the present distribution of barley rusts in North America is dueto a single colonisation, followed by diversification onto different hosts,rather than repeated colonisations by different species.
A comparison of the phylogeny with that of the host could be interesting indetermining whether the pathogens "track" their host's evolution, orwhether they make "jumps" between different hosts. In the days ofgenetic engineering, this may have a practical application. If the rust evolvesby jumping between host species, then transferring resistance alleles betweenspecies may not produce durable control, as we would already be aware that therust is able to overcome the new resistance.
At this time, half time was reached. The entertainments during the intervalconsisted of a meal at the Burgers' Bush, the tropical house of a zoo nearArnhem - a unique, if rather noisy venue. The dinner organisers were obviouslyconcerned for our health, making us walk to different parts of the house to getto the next course. Apart from the animals, entertainments were provided by speeches.
Roy Johnson gave a combined sketch/speech, in his normal ebullient and selfeffacing style, recalling his deeds and mis- deeds on and off the tennis court.At the next course another speech was given. Unfortunately, the microphone didnot appear to work as intended, and the speech was inaudible except for twosoundbites - "listen to me" and "we can communicate".Michael Lynkjær was astonished to be told that he should go and shakehands with the speaker, and receive an envelope. Only upon sitting down did hediscover that he had won the poster prize. Indeed, only upon sitting down did hediscover that there was a poster prize.
The next day we were back to the science. In combating rusts, most effort isfocussed on the major resistance genes. This constrasts with mildew where lesseffort is being put into researching major resistance genes, and instead othermethods of control are being investigated. This dichotomy could be seen in thethird theme to the conference, "Genetic variation for resistance in hostplants". Most of the presentations were about rusts, and concerned theutilisation of major genes. Of course, there are more rust species than mildews,so this might not be surprising.
However, there was a more even split between the pathogens when partialresistance was being investigated. It is accepted that most major genes willprobably not provide durable resistance towards mildew, so alternative methodsof control are being investigated. Because partial resistance is normallypolygenic, breeding strategies become more complicated. Once more molecularmarkers spring to the rescue, with the advent of QTL (Quantitative Trait Loci)analysis. This is a method for trying to find genes affecting a quantitativephenotype by correlating the phenotype score with the presence or absence ofmarkers. Two talks, by Rachel Hague (John Innes Centre, UK), and Xiaoquan Qi(Wageningen, Netherlands) outlined the progress made in trying to find QTLs forpartial resistance towards wheat mildew and barley leaf rust respectively.
An important issue is that of getting resistance genes into commercialcultivars, and a range of different approaches was covered. Chromosomeengineering methods were described by two speakers for the transfer of rustresistance genes into cultivated wheat (Xiuzhang Xue, Wheat Research Centre ofShaanxi Province, China) and oats (Taing Aung, Winnipeg, Canada), while SheilaKinane (University College Cork, Ireland) described mutagen induced mildewresistance in wheat. The suppression, in certain cultivars, of genes introducedfrom wild relatives with lower ploidy levels was the subject of a talk by R PSingh (CIMMYT, Mexico). Again there were many projects presented on posters,indicating that research into new sources of resistance and their effectivenessis extensive.
Not until the final part of the conference did we finally talk about thewhole point of studying rusts and mildew - "Epidemics and diseasemanagement". Most presentations were on the former, although there hadalready been some talks on mixtures - masquerading as population dynamics. Themethod of control that received most attention in this part of the conferencewas the use of fungicides. We got different aspects of their study - genetics(James Brown, John Innes Centre, Norwich), physiology (M Stark- Urnau, BASF,Germany) and population dynamics (Jörn Pons, Giessen, Germany). Theepidemiology was very much a mixed bag - from modeling the effects of climate onoverwintering in leaf rusts in the USA (M G Eversmeyer, Kansas State University,USA) to investigating the removal of rust spores from wheat leaves (L Geagea,INRA, France).
The conference was a valuable and comprehensive summary of the current workbneing carried out on rusts and powdery mildews. In this aspect it was goodbecause there was emphasis on current results, with many younger speakerspresenting their results for the first time. The introductory overviews followedby shorter talks made the structure of each theme easy to follow and there wasplenty of time to exchange ideas and make new acquaintances. The woodedsurroundings provided a laid-back atmosphere, although somewhat isolated. Theorganisers had been adventurous and arranged several excursions, including avisit to the Flevoland polders, as well as the trip to the zoo. The organisersmust be acknowledged for their thorough planning and attention to the needs ofthe participants.
It was certainly an exciting meeting, and there was something in theconference for all those studying mildew and the rusts. Given that most of usspecialise into a small subject area, it is nice to find out what others aredoing to our beast of study, although in Henriette Giese's case this doesinvolve shooting it! It will probably only be through concerted action onseveral fronts that mildews and rusts can be controlled, and conferences likethis one give those working on specific diseases a chance to meet and theirideas to cross-fertilise.
Risø National Laboratory, Denmark
University of Nottingham
Diagnosis and Identification of Plant Pathogens
European Foundation for Plant Pathology: 4th Symposium
9-12 September, 1996
This international conference was held at the Institute for Plant Diseaseswhich is part of the University of Bonn. There were about 250 delegates frommore than thirty countries including quite a number from Eastern Europe.
The first session dealt with general aspects of plant pathogen diagnosis.Emphasis was placed on the distinction between detection and diagnosis;detection methods indicate whether a particular pathogen is present or not,whereas diagnosis is the art of interpreting the nature of a diseased conditionby examination and evaluation of symptoms and detection methods.
Phytosanitary implications were also discussed; accurate pest risk analysesand robust diagnostic protocols are important for phytosanitary regulations andother political implications such as trade barriers. The infamous mad cowdisease (BSE) was used as an example of a political and quarantine problem.
The second session was on taxonomy and differentiation, which covered a widerange of techniques including serological methods, fatty acid analysis, electronmicroscopy and molecular methods. This wide range of detection means that veryspecific criteria are needed for the sort of diagnosis required for each plantpathogen, i.e. level of sensitivity, specificity and which part of the plant istested (roots, seeds, leaves, flower or fruit) and the number of samples thatneed to be tested within a particular time period. There were also exampleswhere a combination of techniques provided a more effective detection system,e.g. the use of PCR- ELISA for the detection of Phytophora fragariae (PBonnants) and the use of immunocapture RT- PCR for detecting beet necroticyellow vein virus (R Koenig).
There were numerous examples of using rDNA sequences for taxonomy of fungalplant pathogens. John Bailey gave an interesting talk on the analysis of rDNAsequences for Colletotrichum, saying it should form the basis of a newtaxonomy for this genus. Other speakers presented data on the diagnostic use ofPCR, RFLP and species specific primers for ITS (internal transcribed spacer)sequences which have been an effective detection method and are used in routinediagnosis.
It was clear from several of the presentations that there is a need for alarge throughput of some pathogen tests. This may be achieved by automation ofmolecular techniques which excludes electrophoresis. Techniques such asPCR-ELISA, DIAPOPS (single phase PCR test in a microtitre plate), Taqman (afluorescent detection system developed and patented by Perkin Elmer) andnon-radioactive dot blot assays are being evaluated and optimised at variousresearch institutes for ease of use, speed, cost, sensitivity and specificity.
There were ninety poster titles included in the program but unfortunatelyquite a few were not presented at the Poster session. There was a time slotallocated each day for the posters which allowed plenty of time to study andabsorb all posters of interest. An evening boat trip along the Rhine and areception with the Mayor provided pleasant social activities for thisconference.
I am most grateful to the BSPP and NIAB for the funds which enables me toattend this interesting meeting.
Emily J A Blakemore
National Institute for Agricultural Botany, Cambridge
Spectroscopy & Optical Techniques in Animal andPlant Biology
Organised by the German Botanical Society and the German ZoologicalSociety
30 Sept to 3 Oct 1996
Some remarkable techniques are now available for visualising and analysingbiological material. This conference provided an excellent opportunity fordelegates with a wide range of research interests to exchange ideas on thedevelopment and application of some of these techniques.
In the opening session on nuclear magnetic resonance (NMR), delegates wereshown impressive examples of the application of this group of techniques to bothanimal and plant systems. A Haase (Wurzburg) demonstrated how the new NMRspectrometers of high field strength can be used to overcome some of thedifficulties normally associated with the method as an analytical tool -principally low spatial resolution and peak-to-background ratio. The newinstruments are currently being used in his laboratory to measure flowvelocities in xylem vessels, and regional distribution of metabolites (e.g.sucrose, glucose and amino acids) in a range of plant tissues.
Richard Bligny (Grenoble) showed some elegant work in which NMR was used tostudy pH regulation and the effects of hypoxia in suspension cultures of plantcells. He showed how the ability to distinguish the position of a labelledcarbon atom could allow dynamic processes such as respiration in living cells tobe studied in real time.
On the second day the topics were infrared and raman spectroscopy. YvesMarechal (Grenoble) showed how infrared spectroscopy can reveal not only thechemical composition of plant cuticles, but can also yield information on thedegree of hydration and the type of bonding which exists between water andcuticular components. This technique could clearly have very interestingapplications for those of us studying interactions between plants and foliarpathogens.
Many interesting applications of fluorescence, phosphorescence andluminescence techniques were described on the following day, and Pierre Viallet(Perpignan) gave a particularly revealing overview of the advantages andlimitations of these techniques. In the evening, delegates enjoyed a fascinatinglecture by invited speaker Thomas Vogelmann (Laramy, U.S.A.), who began byshowing that epidermal cells can act as lenses, and then demonstrated the use ofmicro light sensors to investigate pathways of light through leaves.
The final sessions covered confocal microscopy and its applications to thestudy of signal transduction pathways, fibre optic microprobes, videomicroscopy, and other special techniques. In my own paper I presented work fromthe laboratory of Deri Tomos (Bangor) showing how turgor, osmotic pressure, andthe full complement of solutes can be measured in individual plant cells. I amcurrently applying these techniques to a study of the interaction between barleyand Erysiphe graminis.
In addition to the talks, some seventy posters were presented, and we weregiven ample opportunity to get acquainted with other delegates over someexcellent food and drink. The German enthusiasm for barbecues was not dampenedby the weather - they simply moved the whole affair indoors! I would like tothank Rüdiger Paul and his associates for organising the conference, andthe BSPP for contributing to my expenses.
University of Wales, Bangor
Pests & Diseases was the theme for this year's annual BrightonConference, organised by the British Crop Protection Council. Technical andresearch delegates and commercial representatives flocked from all corners ofthe world to discuss topics as varied as precision farming, biotechnology,disease resistance, temperate and tropical pests and diseases and environmentaland legislative issues.
I estimate that there were over 1500 participants, attending more than 90platform and poster presentations, two evening discussions and two exhibitions.There was a Trade Services Exhibition with some 160 exhibitors involved insupply of goods and services to the agrochemical industry, and a somewhatsmaller Scientific and Educational Exhibition with 14 exhibitors, including UKUniversities offering training in Crop Protection.
A one-day pre-conference symposium investigated the opportunities forimproved crop production by introduction of non- indigenous beneficialorganisms.
The main conference started with the Bawden Lecture, in which Allan Buckwellof Wye College gave an account of Europe's Common Agricultural Policy (CAP). Thestatus quo has been described by the European Commission as not being a viableoption, and policy changes are inevitable. Prof Buckwell envisaged a moreintegrated agricultural policy, not based on a system of price support forindividual commodities, but encouraging rural and environmental development on aregional and local scale. In such a system, which could be in place in as littleas 10 to 15 years, farmers would be competitive providers of foods but couldalso be contracted to provide countryside and environmental services.
Inducing plants' natural resistance
Ciba reported on their plant activator, which is sold in Germany among othercountries under the trade name Bion 50. It affects a wide range of diseases,including Erysiphe graminis in cereals, but does not have any directeffect on fungi or bacteria. It induces the plant's natural defenses, forinstance by increasing papillae formation and thus reducing leaf penetration.Plant activators or elicitors form the basis for novel crop protection agentsthat exploit a natural phenomenon in plants, referred to as systemic acquiredresistance (SAR) by some speakers and systemic activated resistance by others.
A separate platform session was devoted solely to this technology. Someresearchers deemed the word "natural" inappropriate in this context,arguing that plant extracts concentrated in the lab were not natural anymore.Although compounds based on this technology will be subject to the same rigoroussafety testing as standard crop protection agents, some concerns over safety andinsufficient knowledge were expressed.
The new transgenic crops from the US, containing BT and glyphosateresistance genes were the subject of an evening discussion. A wish for specificlabelling of transgenic crops to enable distinction from others was expressed.
The platform presentations were generally of a high quality. Many delegateswere impressed by M.G. Ford's presentation. Explaining how key properties, suchas physical state, fluidity, adhesion and surface energy can be adjusted toincrease pick-up of the active ingredient of pesticides from plant surfaces bytarget insects, as well as to optimise performance at reduced dosage, he gavehis entire presentation straight from his laptop. The poster presentationsranged from flashy industrial posters to posters from UK research institutes,all of an incredibly high standard, to others that clearly did not have thefacilities to compete on such a high level. The informative value of the posterswas generally very good.
Thank you for the BSPP Travel Award which partly financed this trip. TheBrighton Conference was an excellent platform to exchange ideas with otherlike-minded researchers, but at a time of increasing specialisation in researchit was also an opportunity to gain a wider appreciation of the field of cropprotection. Brighton itself was an ideal place for a conference. It boastedimpressive architecture and the flair of a seaside resort, and when it came tosocialising in restaurants and pubs in the evenings, delegates were truly spoiltfor choice.
The only thing we could have done without, were the gale-force winds whichthreatened to blow delegates off their feet, and made walking along theseafront, where the conference centre was located, a risky undertaking.
The weather was pleasant on the first day, but constant drizzles andblustery winds on the following days forced most conference participants to stayin-doors and listen attentively to the proceedings! The posters covered variousareas such as biological control, mode of action of pesticides, epidemiologicaland physiological studies and environmental fate and effects concisely. TheScientific and Educational Exhibition held in the Brighton Centre wasinformative.
The session on "New compounds, formulations and uses for diseasecontrol" presented new developments in chemicals and micro-organisms forcontrol of crop diseases. The emphasis was on novel active ingredients.DPX-JES74, a broad-spectrum fungicide with a new mode of action from DuPont wasuseful against downy mildew of grape and various dieseases on tomatoes,potatoes, wheat and barley. DowElanco offered DE-795: a novel fungicide for thecontrol of powdery mildew in cereals which works by inhibiting appres soriaformation.
Ecogen Inc. reported Ampelomyces quisqualis: a new biofungicide, tocontrol powdery mildew in grapes, pome fruit, strawberries, vegetables,ornamentals. It is formulated as water dispersible grandules which are stablefor 3-4 months at room temperature. The product can be used up to the day ofharvest.
The plant activator CGA 245704 from Ciba-Geigy induces the natural defencemechanism in plants it activates plant resistance, inhibiting certain funalstages in e.g. Peronospora in tobacco. Low rates (12- 30 g ai/ha) giveadequate protection in cereals, tobacco, rice, bananas and vegetables. Thiscompound attracted quite a lost of attention due to its unusual mode of action.
Disease control in fruit and vegetables
The "Pests and diseases in viticulture - current problems and solutions"session offered solutions ranging from the conventional use of agrochemicals tothe forward-looking breeding and gene manipulation techniques. Powdery mildewcauses the most damage to grapes in North America. Bunch rot, a vartiety ofinsects and viruses also attack the plants. The speaker offered varioussolutions to some of these problems. Another speaker on the control of bunch rotcited resistance and residue problems. He suggested alternating fungucides withdifferent modes of action with one spray per season.
In addition to integrated control strategies, forecasting techniques andnovel, non- chemical methods of control, the session on "Advances in arablecrop protection" covered strategies for the management of pests anddiseases, in line with our increases understanding of biology and epidemiology,economic and environmental pressures and legislation.
Pest and disease control in fruit and vegetables was targeted at bothmaintenance of yield and quality. The session dealt with a range of topics ofcurrent interest and importance of researchers and growers. The control of Trichodermaharzianum. a weed mould of mushroom cultivation was of particular interest.The fungus colonises the compost and causes disease in the mushrooms. Fungicidessuch as procloraz had been used in the post, but BavistinR (carbendazim) was nowproviding more effective.
Cultural control and inegrated crop management are both based on theprinciple of crop management practices which made the crop environmental lessfavourable for pest and disease colonisation, reproduction, survival anddispersal, while favouring population growth of natural enemies. The use of cropmanagement techniques were addressed in terms of pest and disease control andconservation of natural enemies. Pest and disease prediction, host plantresistance, novel pesticides, biological and cultural control methods, andattempts to integrate these in the protection of horticultural crops werecovered in the session on "Advances in horticultural crop protection".
Plant pathogenic prokaryotes (bacteria, including phytoplasmas) cause a widerange of diseases and severe crop losses in tropical areas. However, the resentadvances, in the rapid and accurate diagnosis of such diseases using moleculartechniques, and on the scientific basis for disease management give fresh hope.
The interactions between Pseudomonads and Phaseolus beans and theexploitation of genotype mixtures in subsistence agriculture was well covered.The bean grows in the cooler parts of East Africa. The most imortance disease isangular leaf spot. Anthracnose, halo blight and monoculture; farmers in Tanzaniaseem to be well aware of the advantages of planting certain bean varieties incertain seasons, and therefore reducing levels of disease.
I am very grateful for a BSPP travel grant which partly financed myattendance at this conference.
University of Reading
8th Annual Congress of the Postgraduate Institute ofAgriculture
University of Peradeniya, Sri Lanka
This Congress was organised by the Postgraduate Institute of Agriculture(PGIA) of Peradeniya University and was held at the Plant Genetic ResourceCenter near Kandy in the Sri Lankan hill country. The impressive openingceremony, on 21st November, started with a lively rendition of the nationalanthem and continued with due ceremony involving the lighting of an elaborate 6ft. high oil lamp by all of the chief organisers and guests of the Congressaccompanied by traditional Kandyan drummers. Several speeches were made to thankthe organisers of the Congress and set the scene for the following paperpresentations. The theme of the introduction was concern for the state ofAgriculture in Sri Lanka. At present the country cannot produce enough rice andother foodstuffs to meet the demand of its population. At the same time importsfrom Thailand, China and India are drying up. There was a strong emphasis ondeveloping research directly relating to improved field production of cropswhile preserving the environment.
The presentations proper commenced after coffee and two parallel sessionswere run over two days. The session topics covered all aspects of agricultureincluding: agronomy and crop experimentation, agricultural communication, soilscience, genetics and plant breeeding, irrigation and remote sensing studies,biotechnology, natural resource management, plant physiology and post harvesttechnology, animal science and aquaculture, and last, but not least, pestdisease management.
The standard of paper presentation was high and the participants should becongratulated especially as for many of them it was their first publicpresentation of their research findings (the criteria for inclusion in theconference was completion of a higher degree no more than two years previously).The majority of participants were from Sri Lanka but representatives from India,Australia, Switzerland, Japan and the UK were also present.
The two invited speakers were Prof C Wenk from the University of Zurich ("Modernbiotechnology in animal nutrition for a higher productivity with lower pollution")and Dr Anna L Snowdon from the University of Cambridge ("Forensic postharvest pathology in the context of ships' cargoes of fruits and vegetables").Dr Snowdon gave a thoroughly interesting and entertaining presentation includingsome case studies. As she pointed out the word "forensic" pertains tolaw and the results of her investigations of spoiled cargoes are used in legalwrangles over "who is to blame". One case example studied the spoilageof a shipment of bananas caused by the ethylene gas released from rottingoranges stored in hold below the bananas. The law suits went on for more thanthree years and may still be going!
For me this was an excellent forum for the presentation of my work on afungal pathogen of a tropical crop (witch's broom disease of cocoa in SouthAmerica). The hard work I had put into preparing the paper and slides wasrewarded by being judged the best presentation in the session (an award wasgiven for each session). The atmosphere of the entire Congress was of enthusiasmwith researchers keen to discuss their own and others work. Congratulations mustbe extended to Dr Colin Peiris who bore the ultimate responsibility for thesmooth running of the Congress, and to all of the committee members who hadobviously put much effort into making the whole meeting a resounding success.
After attending the PGIA Congress, I visited the University of PeradeniyaCrop Science Department where I was welcomed by Ms Renuka Karunagoda (lecturerin botany and plant pathology) who extended true Sri Lankan hospitality to me. Istayed with Ms Karunaoda and her family in the beautiful tropical setting of theUniversity campus and was encouraged to experience much of the local culture andcuisine (including the wonderful range of curries available for breakfast, lunchand dinner!)
The students at the PGIA could not have been more friendly and organised aday trip for overseas participants to visit the impressive Temple of the Toothin Kandy and the nearby Pennawela elephant orphanage. Later I travelled withsome of the students to visit the Uda Walawe National Park and to climb theawesome Sri Pada Mountain.
During the latter part of my stay I travelled north to visit Mr RanaweeraBanda (a contact in the Government Department of Agriculture) whose family againextended the then familiar, Sri Lankan hospitality. Mr Banda gave me aninteresting insight into the problems of irrigation dependent agriculture. He isalso involved in research into the mysterious chili narrow leaf diseaseaffecting producting of this crop in Sr Lanka (no meal in Sri Lanka could beserved without chilies!). Research has not yet determined the cause of thisdisease, whether pathogenic or physiological, and much interesting research liesahead.
I hope that my participation in the 1996 PGIA congress will help to maintainlinks with researchers in Sri Lanka and will encourage others to support thePGIA's efforts to raise international awareness of their research both at homeand overseas. I would like to thank the BSPP and the University of NottinghamPlant Science Department for help in funding my travel to the PGIA congress andallowing me to maintain contacts in such an amazing, beautiful and diversecountry.
Unlocking the Future
BSPP Presidential Meeting: Information Technology in Plant Pathology
&(with the Systematics Association): Computer-based Species Identification
University of Kent, Canterbury
16-19 December 1996
These are my personal impressions of this well organised and extremelystimulating conference. Fortified by a substantial lunch, I plunged into thepractical and tutorial sessions on the first afternoon. I floated in and out ofCABI's forthcoming CD-ROM, "Compendium of Crop Protection" (at presentbased mainly on SE Asia), then explored the hidden layers of neural networksbefore surfacing to surf the Net.
The next day in his Presidential address, Peter Scott gave a fascinatingdisplay of the power of computer chips. I was even more amazed by his ability tocontinue talking rationally through a succession of computer crashes. Through itall we sensed his enthusiasm for his recently adopted subject - computers reallyare fun!
In his eye-opening keynote speech for the Systematics Association, ProfessorSneath explained a lot when he admitted that "species, like beauty, is inthe eye of the beholder". This enabled Frank Bisby to give us a bird's eyeview of species identification in the third millennium. We will havedescriptions of 1¾ million known organisms at the touch of a button. SimonJones told how this would operate with data warehouses interlinking data frommany sources; the data can then be mined for nuggets of information. But willthe information be entirely accurate?
Ian Smith introduced the uncertainty principle in his attempts to keeppathogens in their place: they may or may not be in places where they areofficially stated to be! The misidentification of many species inColletotrichumwas cited by John Bailey when he highlighted the need to record accurately theorigin of organisms. Uncertainty also pervades the field of molecular genetics:Stephen Oliver queried whether around 50% of the yeast genome really wasredundant; it could have a quantitative contribution to make and we should watchthis space.
On the application of computer-based species identification, ProfessorPankhurst would not hanky-panky with any database other than a relational oneand the only proper format was the DELTA format. In this system R Fortuner likesto pre-digest (his word decompose) whole organisms to molecules via theircomponent parts (systems, organs etc.) and predicts that the prototype NEMISYS(for nematodes) will blossom into GENISYS (for general use).
On the other hand, Mike Dallwitz is keen to feed the system interactivelywith whole butterflies and grasses. Will this resucue us from a loomingbiodiversity crisis, beset by declining taxonomic expertise and problems inhandling the flood of information? Yes, according to Peter Schalk, his software(Linnaeus II) will take the world's biodiversity on board (a kind of Noah'sArchive?).
All this must depend on archiving high quality images. Philippe Blaise gavea practical example of how useful superimposed images can be in plant pathology;a Geographic Information System helped to establish that canker of plane treeswas spread by pruning, not by insects.
As if to illustrate his theme that "keys without pictures don"twork', D Roberts struggled manfully to describe invisible dinoflagellatesthrough every speaker's worst nightmare, a projector failure. Will computerisedimages be more reliable? Within a very busy poster and hands-on demonstrationsession, Charles Lane showed us how images could be captured and licked intoshape.
Mike Jeger brought us back to basics in his Garrett Memorial Lecture withthe concept of "basic reproductive number" helping to decide whetherto rogue or not to rogue and with a potential refurbishment of Garrett'sinoculum potential to improve disease management.
When it comes to teaching plant pathology, Gail Schumann reinforced apervading theme that "a picture is worth a thousand words". In the APSPlant Disease Video Image Resource, she has a videodisc of nearly 10,000 imagesat her fingertips. Pierce Jones' talking pictographs get the message across toworkers about the hazards of chemicals and Zuo Rui Shen's images spread theimportance of plant quarantine insects amongst China's plant health inspectors.Terry Steward reminded us that teaching should not be all work and no play; muchfun can be had in turning Diagnosis into an adventure game.
By all accounts Geoff Norton's software products for diagnosing and managingpests and diseases in Australia are great fun. Bugmatch has moving images ofcaterpillars and a magnifying glass to enlarge any part of the image and LucIDhas a builder for easy key construction. Every game involves a winner which thejudges of the P H Gregory paper reading competition found to their cost; theyagonised long and hard to pick one from a set of five excellent papers.
In concluding orations, Stephen Black more, as Chair of the SystematicsAssociation returned to the theme of archiving biodiversity before we lost itand Peter Cochrane of BT echoed Peter Scott's introduction on the incrediblepace of computer progress. How does the human brain cope with computer powermore than doubling every 18 months? He resented being "silicomorphized"and instead insisted that IT should be made people-compatible. He showed us aglossy advertisement of a sports car selling in 1970 for $8,000. It was anothereye-opener to be told that if these cars had kept pace with computerdevelopment, they would now cost 80 cents and travel at Mach 6! Thank goodnessthey haven't kept pace, otherwise six of them would now fit on the head of apin!
The venue was interesting; a modern university within sight of CanterburyCathedral. It also exercised delegates' orienteering skills when navigatingbetween lecture theatres. The excellent Presidential dinner was meticulouslyplanned by Peter Scott down to the provision of a very acceptable local whitewine. His after-dinner speech complete with renderings from Chaucer's "TheMiller"s Tale' reminded us that there was fun even before the age ofcomputers.
It remains for me to thank the organisers and contributors for all theirhard work and last but not least the BSPP Travel Fund for assistance towards mytravel costs.
Roger T A Cook