Climate change and plant disease

Transcription

1 Climate change and plant disease Karen A. Garrett Kansas State University Photos: Gordon, UCD

2 Outline Plant disease and ecosystem The usual challenges for managing plant disease Implications of climate change Potential interactions and thresholds Responding to climate change

3 Ecosystem : Services provided to humans by ecosystems, including provided by plants and their pathogens (see Millennium Ecosystem Assessment 2005) Provisioning Food Fiber Fuel Fresh water Genetic resources Photo: CIP

4 Other forms of include: Supporting Soil formation Nutrient cycling Primary production Provisioning Food Fiber Fuel Fresh water Genetic resources

5 Provisioning Food Fiber Fuel Fresh water Genetic resources Regulating Climate Disease Water Water purification Supporting Soil formation Nutrient cycling Primary production

6 Provisioning Food Fiber Fuel Fresh water Genetic resources Supporting Soil formation Nutrient cycling Primary production Cultural Ecotourism Agrotourism Aesthetics Education Recreation Inspiration Regulating Climate Disease Water Water purification

7 Damage by disease and insect pests results in approx. 42% loss in the eight most important food and cash crops (Oerke et al. 1994) This is a loss of > $300 billion Plant disease pressure Provisioning Food Fiber Fuel Fresh water Genetic resources Supporting Soil formation Nutrient cycling Primary production Regulating Climate Disease Water Water purification A broader definition of successful management: Plant disease and ecosystem Cheatham et al., in preparation Cultural Ecotourism Agrotourism Aesthetics Education Recreation Inspiration

8 Provisioning Food Fiber Fuel Fresh water Genetic resources Methods for disease management Supporting Soil formation Nutrient cycling Primary production Plant disease pressure Tillage for disease management Need for resistant varieties (with potentially lower value) Application of pesticides Regulating Climate Disease Water Water purification Cultural Ecotourism Agrotourism Aesthetics Education Recreation Inspiration

9 Plant biodiversity Alternate hosts Non-hosts Insect biodiversity Pathogen vectors Natural enemies of vectors Microbial biodiversity Pathogens Biocontrol organisms/ Disease suppressive soils Plant disease pressure Methods for disease management Tillage for disease management Need for resistant varieties (with potentially lower value) Application of pesticides Provisioning Food Fiber Fuel Fresh water Genetic resources Supporting Soil formation Nutrient cycling Primary production Regulating Climate Disease Water Water purification Cultural Ecotourism Agrotourism Aesthetics Education Recreation Inspiration

10 Provisioning Food Fiber Fuel Fresh water Genetic resources Supporting Soil formation Nutrient cycling Primary production Plant biodiversity Alternate hosts Non-hosts Microbial biodiversity Pathogens Biocontrol organisms/disease suppressive soils Insect biodiversity Pathogen vectors Natural enemies of vectors Plant disease pressure Methods for disease management Tillage for disease management Need for resistant varieties (with potentially lower value) Application of pesticides Regulating Climate Disease Water Water purification Cultural Ecotourism Agrotourism Aesthetics Education Recreation Inspiration

11 Biological impacts from beyond target region Global genetic resources: Provisioned by many different ecosystems Disease resistance genes in crops New invasive pathogens Provisioning Food Fiber Fuel Fresh water Genetic resources Supporting Soil formation Nutrient cycling Primary production Plant biodiversity Alternate hosts Non-hosts Microbial biodiversity Pathogens Biocontrol organisms/disease suppressive soils Insect biodiversity Pathogen vectors Natural enemies of vectors Plant disease pressure Methods for disease management Tillage for disease management Need for resistant varieties (with potentially lower value) Application of pesticides Regulating Climate Disease Water Water purification Cultural Ecotourism Agrotourism Aesthetics Education Recreation Inspiration

12 Biological impacts from beyond target region Global genetic resources: Provisioned by many different ecosystems Disease resistance genes in crops New invasive pathogens Provisioning Food Fiber Fuel Fresh water Genetic resources Supporting Soil formation Nutrient cycling Primary production Plant biodiversity Alternate hosts Non-hosts Microbial biodiversity Pathogens Biocontrol organisms/disease suppressive soils Insect biodiversity Pathogen vectors Natural enemies of vectors Plant disease pressure Methods for disease management Tillage for disease management Need for resistant varieties (with potentially lower value) Application of pesticides Regulating Climate Disease Water Water purification Cultural Ecotourism Agrotourism Aesthetics Education Recreation Inspiration

13 Policy Support for conserving and utilizing genetic resources Policies to control movement of plant materials Plant biodiversity Alternate hosts Non-hosts Microbial biodiversity Pathogens Biocontrol organisms/disease suppressive soils Insect biodiversity Pathogen vectors Natural enemies of vectors Biological impacts from beyond target region Global genetic resources: Provisioned by many different ecosystems Disease resistance genes in crops New invasive pathogens Plant disease pressure Methods for disease management Tillage for disease management Need for resistant varieties (with potentially lower value) Application of pesticides Provisioning Food Fiber Fuel Fresh water Genetic resources Supporting Soil formation Nutrient cycling Primary production Regulating Climate Disease Water Water purification Cultural Ecotourism Agrotourism Aesthetics Education Recreation Inspiration

14 Policy Support for conserving and utilizing genetic resources Policies to control movement of plant materials Biological impacts from beyond target region Global genetic resources: Provisioned by many different ecosystems Disease resistance genes in crops New invasive pathogens Provisioning Food Fiber Fuel Fresh water Genetic resources Supporting Soil formation Nutrient cycling Primary production Plant biodiversity Alternate hosts Non-hosts Microbial biodiversity Pathogens Biocontrol organisms/disease suppressive soils Insect biodiversity Pathogen vectors Natural enemies of vectors Plant disease pressure Methods for disease management Tillage for disease management Need for resistant varieties (with potentially lower value) Application of pesticides Regulating Climate Disease Water Water purification Cultural Ecotourism Agrotourism Aesthetics Education Recreation Inspiration

15 Policy Farm Bill: in US, subsidies provide Support for conserving pressure and for great utilizing genetic resources abundance of a few crop Policies to control species movement of plant materials Payment for ecosystem : e.g., US Conservation Reserve Program Plant biodiversity Alternate hosts Non-hosts Microbial biodiversity Pathogens Biocontrol organisms/disease suppressive soils Insect biodiversity Pathogen vectors Natural enemies of vectors Biological impacts from beyond target region Global genetic resources: Provisioned by many different ecosystems Disease resistance genes in crops New invasive pathogens Plant disease pressure Methods for disease management Tillage for disease management Need for resistant varieties (with potentially lower value) Application of pesticides Provisioning Food Fiber Fuel Fresh water Genetic resources Supporting Soil formation Nutrient cycling Primary production Regulating Climate Disease Water Water purification Cultural Ecotourism Agrotourism Aesthetics Education Recreation Inspiration

16 Policy Support for conserving and utilizing genetic resources Policies to control movement of plant materials Biological impacts from beyond target region Global genetic resources: Provisioned by many different ecosystems Disease resistance genes in crops Provisioning Food Fiber Fuel Fresh water Genetic resources Farm Bill: in US, subsidies provide pressure for great abundance of a few crop species Plant biodiversity Alternate hosts Non-hosts Payment for ecosystem : e.g., US Conservation Reserve Program Microbial biodiversity Pathogens Biocontrol organisms/disease suppressive soils Insect biodiversity Pathogen vectors Natural enemies of vectors New invasive pathogens Plant disease pressure Methods for disease management Tillage for disease management Need for resistant varieties (with potentially lower value) Application of pesticides Supporting Soil formation Nutrient cycling Primary production Regulating Climate Disease Water Water purification Cultural Ecotourism Agrotourism Aesthetics Education Recreation Inspiration

17 Outline Plant disease and ecosystem The usual challenges for managing plant disease Implications of climate change Potential interactions and thresholds Responding to climate change

18 Management options Disease resistance is generally the best option, if available Pesticides are often an option, sometimes with associated health and environmental risks, not to mention economic costs Particular diseases may have other options, such as sanitation, biocontrol, tillage, and use of certified seed

19 For rice blast, single R genes have not offered long-lasting protection Blast R gene Release Breakdown Adapted from Lee and Cho, International Rice Research Conference, Seoul, 1991

20 Connected regions for pathogen types with different tolerances to the cost of limited host availability Margosian, Garrett, Hutchinson, and With Farm policies that support vast acreages of a single crop species increase the risk of rapid pathogen movement throughout the highly connected plantings

21 Rice blast management through genotype mixtures (Yunnan Province) - Zhu et al Nature The rice variety mixtures are now used on over 1 million hectares in China More recently, studies indicate that microclimate changes from mixing varieties play an important role in reduced disease in this system Strategically selected intraspecific plant diversity can be effective for disease management, especially as a component in an integrated disease management plan

22 Potato late blight can only be managed in some regions with more than 10 pesticide applications a season Image c/o CIP and CARE farmer field schools and collaborators

23 Fungicide applications as a function of climate For well-known diseases, we can make rough predictions about the demands for management as temperature and precipitation change Estimates of regional reliance on fungicides for management of potato late blight around Lake Titicaca Using late blight forecasting models based on meteorological variables Forbes, Raymundo, Garrett

24 Outline Plant disease and ecosystem The usual challenges for managing plant disease Implications of climate change Potential interactions and thresholds Responding to climate change

25 Garrett et al. 2006

26 ECOLOGY GENETICS Ecogen KSU Conceptual Model ECOSYSTEM RESPONSE GENOTYPIC CONTRAINTS ORGANISMAL RESPONSE GENE EXPRESSION POPULATION AND COMMUNITY RESPONSE PHENOTYPIC EFFECT ON DEVELOPMENT/PHYSIOLOGY ECOLOGICAL GENOMICS

27 ECOLOGY GENETICS Ecogen KSU Conceptual Model ECOSYSTEM RESPONSE GENOTYPIC CONTRAINTS GENE EXPRESSION POPULATION AND COMMUNITY RESPONSE In the long run, understanding the genetic constraints for pathogen ORGANISMAL RESPONSE and plant adaptation will allow better mechanistic models of responses to climate change PHENOTYPIC EFFECT ON DEVELOPMENT/PHYSIOLOGY ECOLOGICAL GENOMICS

28 Lower expression of HR and other genes associated with disease resistance in big bluestem in response to simulated precipitation change Travers et al Steve Travers

29 Phytohormone responses to disease and drought stress in big bluestem Erin Frank Jasmonic acid and salicylic acid increase in response to rust infection in plants without drought stress Under drought stress, plants don t respond in this way Drought stress doubles disease severity in this system

30 Xa resistance genes, except Xa7, are less effective at higher temperatures Lesion length (cm) a b a b a b 35 C day/29 C night 29 C day/21 C night b a a a c/o Jan Leach Xa3 Xa4 xa5 Xa7 Xa10 Rice bacterial blight resistance gene Webb et al., unpubl.

31 Stomatal closure and leaf growth inhibition during drought (e.g., Chaves et al. 2003) Plant structural changes in response to CO 2 (Pritchard et al. 1999) Higher fecundity of Colletotrichum gloeosporioides under increased CO2 (Chakraborty and Datta 2003)

32 Garrett et al. 2006

33 Increased CO 2 increased fungal pathogen load in tallgrass prairie (Mitchell et al. 2003) Heating of montane prairie had mixed effects on pathogens (Roy et al. 2004)

34 Needle blight moving northward in North America as temperature and precipitation patterns change (Woods et al. 2005)

35 Phytophthora cinnamomi predicted expansion in Europe due to temperature change from General Circulation Models (Bergot et al. 2004)

36 Soybean rust pathogen immigration to US potentially via Hurricane Ivan Invasive species Kudzu will probably play important role in epidemiology Dry conditions have probably slowed movement through the US

37 Factors for prediction of disease effects on ecosystems (Eviner and Likens, in press) Pathogen effect on host survival, physiology, behavior, and/or reproduction Life stages of a host vulnerable to a pathogen Proportion of individuals/biomass infected at a site Spatial extent and distribution of infection Rate of pathogen effects on hosts in relation to rate of response/recovery by hosts of individuals replacing hosts Frequency and duration of pathogen impact Functional similarity of infected individuals versus replacements

38 Outline Plant disease and ecosystem The usual challenges for managing plant disease Implications of climate change Potential interactions and thresholds Responding to climate change

39 Policy supporting extensive plowing + drought = dustbowl

40 Plant disease triangle Susceptible host Generalization: Virulent pathogen Fungal pathogens benefit from more precipitation Conducive environment

41 Plant disease triangle Susceptible host An environment that is not conducive may obscure the fact that a susceptible host and virulent pathogen are both present Virulent pathogen Conducive environment

42 For potato late Susceptible blight, the potatoes effects of climatic variables for a particular pathogen genotype and host genotype, within a field, are fairly well understood Phytophthora infestans Conducive environment + reliance on potatoes as primary food = Irish potato famine

43 The local inoculum load builds during the period of conducive weather Percentage inoculum saturation Because plant disease pressure often increases following a compound interest model, increasing the length of the growing season slightly can have a very large impact on inoculum load Month 1 Month 2 Month 3 Month 4 Month 5 Month 6 Month 7

44 A conceptual model of the relationship between season length and local potato late blight severity Local processes (Field) Pathogen: Local inoculum load Local disease severity Environment: Local environmental conduciveness to disease during season Host: Local host susceptibility Garrett, Zuniga, Roncal, Mundt, Forbes, Su, and Nelson

45 Regional processes (Valley) Environment: Regional environmental conduciveness to disease during season Pathogen: Regional inoculum load Host: Regional host susceptibility Regional disease severity Local processes (Field) Pathogen: Local inoculum load Local disease severity Environment: Local environmental conduciveness to disease during season Host: Local host susceptibility Garrett, Zuniga, Roncal, Mundt, Forbes, Su, and Nelson

46 Regional processes (Valley) Length of season Local processes (Field) Environment: Regional environmental conduciveness to disease during season Pathogen: Regional inoculum load Pathogen: Local inoculum load Host: Regional host susceptibility Regional disease severity Local disease severity Environment: Local environmental conduciveness to disease during season Host: Local host susceptibility Garrett, Zuniga, Roncal, Mundt, Forbes, Su, and Nelson

47 Regional processes (Valley) Length of season Environment: Regional environmental conduciveness to disease during season Pathogen: Regional inoculum load Host: Regional host susceptibility Effect of regional host diversity Regional disease severity Local processes (Field) Pathogen: Local inoculum load Environment: Local environmental conduciveness to disease during season Host: Local host susceptibility Local disease severity Effect of local host diversity Garrett, Zuniga, Roncal, Mundt, Forbes, Su, and Nelson

48 Regional processes (Valley) Length of season Local processes (Field) Environment: Regional environmental conduciveness to disease during season Environment: Local environmental conduciveness to disease during season Host: Regional host susceptibility Changes in season length may affect Pathogen: the utility of management practices Regional that depend on inoculum load reducing inoculum load at a local level Pathogen: Local inoculum load Host: Local host susceptibility Effect of regional host diversity Regional disease severity Local disease severity Effect of local host diversity Garrett, Zuniga, Roncal, Mundt, Forbes, Su, and Nelson

49 An Allee effect may produce thresholds for pathogen reproduction Results for Tilletia indica, causing Karnal bunt of wheat (Garrett and Bowden 2002; Garrett, Sharma, Tang, Yang and Bowden, in preparation) 1.2 Infected kernels (Proportion of maximum) b a a c b a d Inoculum concentration spray syringe c e

50 An Allee effect may produce thresholds for pathogen reproduction Results for Tilletia indica, causing Karnal bunt of wheat (Garrett and Bowden 2002; Garrett, Sharma, Tang, Yang and Bowden, in preparation) 1.2 Infected kernels (Proportion of maximum) b a a c b Inoculum concentration spray syringe Changes in processes at small c a d pathogen population sizes may have major effects on pathogen dispersal and establishment e

51 Outline Plant disease and ecosystem The usual challenges for managing plant disease Implications of climate change Potential interactions and thresholds Responding to climate change

52 Consistent support for plant disease research spanning from basic to applied is needed in order to manage plant disease well - with or without new challenges from climate change

53 Research needs I Better understanding of gene expression in plants and pathogens in response to climatic factors Integrated omic studies of host and pathogen responses, as well as communities of soil and plantassociated microbes Multifactor studies of climate change effects

54 Research needs II Better models of adaptation rates Better data and models related to dispersal, current levels of intraspecific diversity, strength of selection under different climate change scenarios, and heritability of traits

55 Research needs III Long-term large-scale records of pathogen and host distributions Models of regional processes that incorporate disease Data and models describing dispersal of propagules and vectors Integrated multi-disciplinary international networks for data collection and synthesis

56 US National Plant Diagnostic Network Implemented in part in response to concerns about bioterrorism Will enhance our ability to respond to plant disease Needs to be linked with global networks

57 Need for genetic resources to respond to changing climates International institutions such as the CGIAR center network, with responsibility for maintaining and characterizing plant genetic resources, generally have shoestring budgets

58 Orphan crops such as quinoa, cassava, sweet potato, millets, and teff are of particular regional importance but receive relatively little research attention (Nelson et al., 2004). Quinoa variety trial in Bolivia In tropical regions where food security is a particular concern, there may be greater climate variability and uncertainty combined with less investment in technologies to support crop production. Photo: P. Motavalli

59 Conclusions Plant disease has a major impact on agricultural and natural systems Current strategies for management need to be maintained and improved, even if the climate did not change Climate change will increase some disease risks and decrease others The effects of climate change will be most important when thresholds and interactions occur to produce unanticipated large responses Systems may change more rapidly than in the past, requiring more research and policy attention

60 Acknowledgements US-NSF, USDA, US-DOE, USAID- SANREM, USAID- IPM, NCEAS Ecological Genomics Jianfa Bai Erin Frank Mike Herman Scot Hulbert Loretta Johnson Alan Knapp Jan Leach George Milliken Amgad Saleh Pat Schnable Mendy Smith Steve Travers NCEAS Plant Disease & Ecosystem Services Group Melissa Cheatham Severo Cardenas I. Greg Forbes Tom Gordon Willy Pradel Rubi Raymundo Matthew Rouse Adam Sparks And many other collaborators Disease Ecology Helen Alexander Bob Bowden Shauna Dendy Phil Fay Greg Forbes Greg Gilbert Shaun Hutchinson Peg Margosian Chris Mundt Rebecca Nelson Sunny Power Rubi Raymundo Erminia Roncal Indu Sharma Zhaohui Su Zhongwen Tang Corinne Valdivia Nollie Vera Cruz Cam Webb Kim With Noemi Zuniga

61 Postdoc position

62 Mean proportion plants diseased at Konza Prairie Biological Station Upland Lowland Proportion of (39, 116) (24, 37, 55, 69) (30, 50, 71) (50) Days After June 1 of Each Year