BSPP2006: 25th Anniversary Celebratory Meeting

President: Peter Mills

Imperial College, London 19th December 2006

To celebrate the 25th Anniversary of the foundation of the British Society for Plant Pathology, a special celebratory one day meeting was held at Imperial College, London on 19th December 2006.

The programme of talks was specially organised to reflect the past, present and future interests of the Society.

Peter Mills (BSPP President 2006)

Special 25th Anniversary Articles

• A message from the first president – notes on the origin of the BSPP
  by R K S Wood, BSPP President 1982
• The BSPP: A retrospective
  by Nigel Hardwick, BSPP President 1997
• 25 years for BSPP is an achievement to be proud of
  by Peter Mills, BSPP President 2006
• 25 years of plant pathogen interactions
  by Richard Cooper, BSPP President 2007
• The BSPP: Celebrating 25 Years
  by Nigel Hardwick, BSPP President 1997

Photo Gallery

Abstracts and selected talk downloads from the 25th Anniversary Meeting

The global impact of plant diseases

Peter Scott

BSPP was born 25 years ago because Britain had no professional society devoted to plant diseases and their impact. In fact BSPP had to be born, because the societies closest to plant pathology couldn’t agree on who should manage the journal Plant Pathology, with its practical emphasis on mechanism, impact and management of plant disease. The impact of plant disease is everywhere, and is inadequately appreciated by policy makers – something which immediately suggests a role for BSPP. Considering food crops alone, the 14 staples are subject to more than 100 principal diseases, and to a total of thousands. At least 10% of global food production is thought to be lost to plant disease. Though this estimate lacks a strong base, such losses must make a huge global impact when, according to the World Bank, more than 800 million people do not have adequate food, and more than 1 billion live on less than $1 a day.

The most serious impacts in human terms occur in developing countries, which provide innumerable examples of damaging pathogens of crops and forests, with serious impacts on food security. Impacts in industrial countries may be less obvious, because of better management and because there may be food surpluses, but substantial costs are still incurred. Plant diseases have shaped history: the impact of potato blight in Ireland in the 1840s was starvation for around 1 million people, while more than 1 million attempted to emigrate. In the US, the southern corn leaf blight epidemic of 1970-1 did not cause starvation but threatened the whole corn industry, through its dependence on a narrow genetic base. Equally serious is the poorly quantified ongoing impact of the thousands of species of fungi, bacteria, viruses and oomycetes on crops, forests and wild plants that we plant pathologists live by. It would be a mistake for the discipline of plant pathology to thrive primarily as a field of study for molecular biology, powerful though this is in understanding plant disease. The BSPP recognizes also that plant disease has economic and environmental impact that truly matter in social and economic terms. The International Society for Plant Pathology (ISPP) has a Task Force on Global Food Security with a small programme aimed at influencing public opinion and policy. It is exploring the development of a new journal, which may be called the Journal of Food Security.

Plant diseases are here to stay. We can dream of a world without them, but natural selection will ensure that it remains a dream. BSPP, from its position of authority as a science-based organization, will have much to attend to during its next 25 years. Raising awareness of the impact of plant disease is a critical – and challenging – place to start.

Epidemiology: from individuals to populations

Christopher A. Gilligan, University of Cambridge

J.E. Van der Plank wrote in 1963 that “Chemical industry and plant breeders forge fine tactical weapons but only epidemiology sets the strategy”. This is still true, more than forty years later. It underlines the continued quest for sustainable disease control, which, itself, rests on a paradox. Since most plants are self-evidently resistant to most pathogens, it seems perfectly reasonable to assume that advancing knowledge of the genetical, molecular, and cellular bases of host-pathogen interaction will identify the means not only to engineer or to select durable resistance but also to produce effective and environmentally neutral forms of chemical control. Yet failures still occur and the problems are exacerbated by escalating costs for release of new varieties and for the development and registration of new chemicals. These problems partly reflect differences in scales between screening and deployment underlining the need to integrate epidemiology – ‘the science of disease in populations’ – with molecular biology, and host-pathogen genetics and physiology. Most novel forms of disease control are screened for effectiveness at the small scale. Often this is done at scales as small as the single plant for initial screening, though more usually it involves multiple field plots and ultimately fields. Yet successful deployment – and the risk of failure – occurs at scales much larger than this, at the regional, national or even international scales. The epidemiological challenges are not all technologically driven: agriculture and natural vegetation continue to be confronted by new and recurrent epidemics. The problems in minimising the risks of failures of control and in managing emerging epidemics demand a common epidemiological approach that considers invasion, persistence, scaling and chance.

Having reviewed briefly the progress in epidemiology during the past 25 years, I shall illustrate likely future developments in constructing an epidemiological framework to model invasion, persistence and variability of epidemics that encompasses a wide range of scales and topologies through which disease spreads. By considering how to map control methods onto epidemiological parameters and variables, some new approaches towards optimising the efficiency of control at the landscape scale will be described. Some epidemiological strategies to minimise the risks of failure of chemical and genetical control will be presented and, if time permits, some consequences of heterogeneous selection pressures in time and space on the persistence and evolutionary changes of pathogen populations discussed. Finally, brief mention will be made of how we might embed epidemiological models in an economically-plausible framework for the deployment of control.

Past, current and future disease threats to plants in the United Kingdom

Ian M. Smith, formerly Director-General, EPPO

As an island, the United Kingdom has been particularly concerned to protect itself from the threat presented by the introduction of non-native pests (including plant pathogens). It has taken particular care to develop effective plant quarantine. Twenty five years ago, the British phytosanitary system was still more or less that inherited from the period before EU membership, with an approach akin to that of many island countries around the world, with prohibitions or severe restrictions of plant imports from most other countries. EU membership changed the system, so that by 1993 imports from other EU countries were able to enter relatively freely under the plant passport system, and imports from the rest of the world were regulated by the EU system, which applies prohibitions and restrictions in reaction to specifically identified risks. Through the 1990s, this more specific approach was reinforced by the development of the Sanitary and Phytosanitary (SPS) Agreement of the World Trade Organization, which requires members to provide, if challenged, technical justification of phytosanitary measures. Plant quarantine thus entered the world of “risk analysis”, which primarily allows new pest risks to be evaluated and countered, but secondarily (and more politically) seeks to avoid trade disputes. The major problems which have arisen with the risks from animal diseases (BSE) and LMOs have also had their effects on plant quarantine, which has become more laboriously administrative and “riskaverse”.

Another major development of the 1990s has been the improvement of diagnostics. Plant pathogens can be identified more readily, which is a direct advantage, but disputes about diagnosis, and the distinction between specified risky species and others, become more probable. New diagnostic techniques also make it easier to produce disease-free planting material, which in principle could move with little restriction in international trade. However, international standards are needed to back this development.

The Convention on Biological Diversity (CBD) has recently developed new agreements on the movement of alien species, which overlap to a certain extent with plant quarantine. This has led to a greater focus on risks to plants in native ecosystems, rather than in agriculture or forestry. With a greater political emphasis of the protection of the consumer and the environment, and a lesser emphasis on support for agriculture, these aspects are likely to take on more importance (though in practice risks from invasive alien plants and animals have received most attention).

These various developments over the last 25 years are illustrated by reference to individual cases of plant diseases of phytosanitary importance.

From genetics to plant breeding: what do we know and what do we need to know?

James Brown, John Innes Centre, Norwich

Plant breeding is one of the most revolutionary, life-changing technologies developed in the 20th century. Yet despite the proven success of this technology, the last 25 years have been marked by a severe decline in the teaching of plant breeding in universities and in research on genetics to underpin breeding. Meanwhile, expenditure has flourished on genetic manipulation, a technology which has promised far more than it has delivered. The situation in academia contrasts sharply with the continuing success of the largely private plant breeding industry. A chasm has therefore opened up between research on plant genetics and commercial plant improvement. I will argue that likely changes in the severity of different plant diseases over the next 25 years means that it is now more important than ever to use successful, trustworthy technology to combat them. I will discuss (1) reasons for the decline of plant breeding as an academic subject, (2) what we do (and don’t) need to know about plant genetics, pathogen evolution and pathogenesis to support breeding for disease resistance, (3) how technological developments over the last 25 years have (and haven’t) improved resistance breeding and (4) how the genuine benefits of GM can be integrated with the proven technology of breeding to control disease. Examples will be taken from fungal diseases of cereals.

Agrochemical control: Screening, costs, efficacy and environment

Naomi Pain, Syngenta, Jealotts Hill Research Centre

The last 25 years have seen significant changes in the structure of the agrochemical industry, and the pressures it faces. In agriculture, the need for novel fungicides has persisted. More sophisticated, potent chemistries with novel modes of action and effects have been introduced to the market place. Different properties have required growers to understand the products to use them to best effect, and agribusinesses, advisors and grower groups have provided education and recommendations for improved disease control. However, increasing regulatory requirements and hence development costs of novel products have necessitated an increase in efficiency and cost-effectiveness within the industry.

One result of this has been extensive consolidation. Within research and development, further changes have been made to improve cost savings. Novel technologies (miniaturisation, automated liquid handling, combinatorial chemistry, data analysis systems etc) have enabled the implementation of in vivo (living target based) and in vitro (biochemical target-based) high throughput assays. Success of these approaches is closely scrutinised, and the failure for the industry to deliver on expectations has seen a re-focussing of priorities. We are now seeing the focus shifting towards balance between through put and data quality to meet the business needs of delivery of “blockbuster” products.

Looking forward, in a relatively static agricultural market, the fungicide sector is showing growth. This can be attributed to a number of factors: the emergence of new diseases, increased significance of others, occurrence of resistance to existing products, increasing consumer and processor demand for high quality, consistent food. These areas will be explored further, and a view of the future of crop protection alongside other disease control approaches (biotech, native traits etc.) will be presented.

Alternative control methods

John M Whipps, Warwick HRI, University of Warwick, Wellesbourne

Disease control has traditionally relied heavily on the use of chemicals and disease resistant varieties of plants. However, with increasing resistance of pathogens to chemicals, pressure to decrease chemical use in the environment, and reduced availability of active ingredients for disease control, the need for alternative means of disease control has now become even more important. This is especially so for soil-borne pathogens with the loss of the soil sterilant, methyl bromide. Traditional cultural and environmental procedures are still of value and are being adapted to the current situation. These commonly include quarantine, basic hygiene measures, use of crop rotations, soil steaming, solarization, and organic amendments.

Other more specialised techniques such as micropropagation for virus-free stock, thermotherapy for controlling seed-borne pathogens and vector control are also options. In the glasshouse, where environmental control is possible, other techniques such as humidity, temperature and fertigation control can be utilised as well. In addition, microbial inoculants (biological disease control agents) are gradually entering the market with at least 3 viral products, over 30 bacterial products and 50 fungal products available worldwide, including some recently available in the UK. The potential also exists to integrate some of these alternative disease control methods to enhance disease control further. Some specific examples based on the use of Coniothyrium minitans, Pythium oligandrum and Trichoderma viride will be discussed.

The pathogen; mechanisms of attack and novel targets

John Mansfield, Marta de Torres, Ian Brown and Murray Grant, Division of Biology, Imperial College London

Perhaps the most remarkable discovery in recent years has been that bacteria are able to inject proteins into plant cells. Unravelling the role of the type three secretion system (T3SS) has allowed new perspectives to be developed on mechanisms of innate immunity and their suppression by pathogens. A clear link has been forged between plant and animal pathosystems. The role of effector proteins delivered through the T3SS in the induction of disease and activation of the hypersensitive reaction has provided new insights into the regulation of plant defences.

We have used delivery of proteins through a non-pathogen and also in planta expression to examine the impact of potential effectors on plant defence in Arabidopsis. Our focus is on the HopAB family including AvrPtoB. Using the RW60 strain of Pseudomonas syringae pv. phaseolicola we found that AvrPtoB suppresses basal resistance particularly in the absence of the flagellin (flg22) receptor FLS2. Expression of AvrPtoB in the plant suppressed defences induced by flg22 and also the elf20 peptide, but only if the effector was induced one or two hours before elicitor challenge. The timing of exposure of plant cells to elicitors and effectors has a clear influence on the outcome of interactions. Reduction in callose accumulation was observed and also a reprogramming of the defence transcriptome characterising basal resistance. Disease development and AvrPtoB-induced susceptibility, were associated with increases in abscisic acid (ABA) concentrations and ABA-induced gene expression. The potential and rather unexpected role of plant hormones such as ABA in rapidly modulating the leaf environment to favour pathogenesis will be discussed.

The host: Resistance gene isolation and realising the potential

Kim Hammond-Kosack, Rothamsted Research

Most plants are resistant to most pathogens. This is because plants have evolved sophisticated systems for the recognition of non-self that in turn leads to the activation of both local and systemic plant defence responses. Over the past twelve years many novel genes, proteins and molecules have been discovered as a result of investigating both compatible and incompatible plant-pathogen interactions. We now recognise that both interaction outcomes involve dramatic cellular reprogramming events in plant tissues and that some parallels exist between plant defence and the animal innate immune response.

This presentation will focus on the different classes of resistance genes, how they were isolated, how they are thought to function in pathogen perception and defence activation and how novel functionalities may be evolving at resistance gene loci. Many fundamental questions remain stubbornly unanswered. Where research breakthroughs are urgently required these will be pin-pointed and the value of post-genomics approaches reviewed.

Most of the knowledge gained on resistance genes / proteins and the defence responses activated arose from investigations on model plant-pathogen interactions. Unfortunately most attempts to harness this new knowledge to engineer improved disease resistance in crops have so far failed even though good gene efficacy has been shown. Currently underway is a shift in emphasis towards strategies to enhance marker-assisted breeding and the use of vectors containing highly regulated transgenes that confer resistance in several distinct ways.

Public understanding of plant pathology; what do the public know and what shapes what they know?

Tony Gilland, Institute of Ideas, London

“As the earth’s population expands, and global climate changes, increasing demands are made on our limited cropping area. Ever present pest and pathogen populations continue to cause serious crop losses and, on a world scale, crop protection remains one of man’s principal challenges.” The BSPP and Education, A Career in Plant Pathology?, The British Society for Plant Pathology web site.

However important the work of plant pathologists may be it seems fair to say that the intricacies of plant pathology are not high in the public’s mind. Whilst many a keen gardener may be familiar with some of the challenges posed by an array of plant pathogens, and some of the options available to combat them, the science of plant pathology is simply not a major issue of public concern. That said, what has become a far greater issue of public concern is the way we farm our food. From pesticide residues to genetic modification and organic
farming, debates have raged across the media and elsewhere about this issue and have undeniably had an impact on public perceptions of what science has to contribute to improving the way we grow our crops. How plant pathologists should respond to this situation is an important question for debate.

In addressing this question this paper will focus on two key problems. First, the drawbacks of our media dominated society where whatever does or does not get reported in the pages of the national papers is seen to have a defining impact on public life. Whilst the power of the media is important to recognise there is a real danger of underestimating the wide range of factors that shape public debate – not least of which is the clarity and sense of purpose that any community of professionals has about their work. This leads to the second key problem, defensiveness. Scientists are constantly being berated about the need to engage the public with evermore prescriptive guidance about the best way to do this. But the bigger problem is not so much how to communicate but what. Science has been on the back foot for far too long. The way to address this is not to worry about what the public does or does not know or think, but to insist firmly on the significant contribution science has to make to society and to alter the terms of the debate – at least that way ‘the public’ stand a fair chance of hearing more balanced and genuine debates about the issues from which they can make up their own minds.

Foresight: plant pathology in a global disease context

Jeff Waage, Imperial College, London

The UK Office of Science and Innovation has completed this year a Foresight project on Detection and Identification of Infectious Diseases. This 18 month study considered the future risks of infectious disease across human, animal and plant sectors. The study was focused on both the UK and sub-Saharan Africa. Across these sectors and regions, experts identified the same three future risks as priorities: new pathogens/strains arising through natural genetic change, geographical extension of pathogen range and increased pathogen resistance to microbiocides.

Parallel to risk studies, the project considered future scientific advances affecting
our capacity to detect, identify and monitor infectious diseases. Four areas of technology were seen to converge in future on systems for rapid, pre-symptomatic disease monitoring: gene technology, sensing technology, electronic miniaturization and information technology. In UK and Africa, these future visions of risk and technology were put to practitioners responsible for disease prevention and management, and four “systems” emerged for future development: novel information technology for capture and analysis of disease-related data; tools to detect and characterize new diseases based on genomics and postgenomics; hand held point-of-care devices for rapid disease diagnosis; and high throughput, non-invasive disease detection systems for use in ports, airports. Throughout this project, plant disease perspectives were integrated with those on animal and human diseases. As plant diseases hold a comparatively lesser place in political priorities for infectious disease, such engagement with advances in human and animal disease diagnosis and prevention should be of future value.