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SECURE (QLK5-CT-2002-01813) SECURE QLK5-CT-2002-01813.

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Presentation on theme: "SECURE (QLK5-CT-2002-01813) SECURE QLK5-CT-2002-01813."— Presentation transcript:

1 SECURE (QLK5-CT-2002-01813) SECURE QLK5-CT-2002-01813

2 SECURE StEm Canker of oilseed rape: molecular tools and mathematical modelling to deploy dUrable REsistance.

3 SECURE (QLK5-CT-2002-01813) SECURE What is Oilseed rape? What is stem canker? Current methods of control? The need for durable resistance Project aims? Who benefits from SECURE?

4 SECURE (QLK5-CT-2002-01813) What is oilseed rape (OSR)? Agricultural crop grown throughout most of Europe, SE and W Australia and in Canada and the USA. OSR typically grown in Europe is a Winter type - sown in autumn and harvested the following summer. Crop is grown primarily for seed production – seeds are crushed to produce oil (edible, industrial)

5 SECURE (QLK5-CT-2002-01813) What is stem canker? Globally important disease of oilseed rape Caused by fungus called Leptosphaeria maculans Infects in autumn Major damage at harvest Basal stem canker at end of the growing season

6 SECURE (QLK5-CT-2002-01813) What is stem canker? 1. Airborne spores land on young crop in autumn 2. Spores infect to cause leaf lesions 3. Fungus grows down through leaf to… 4. infect the base of the stem 5. Cankers grow during late spring/early summer and can girdle stem

7 SECURE (QLK5-CT-2002-01813) Current methods of control Fungicide (Chemical control) Environmentally unfriendly Environmentally unfriendly Expensive for the farmer (time/money) Expensive for the farmer (time/money) Cultivation techniques Limited in usefulness Limited in usefulness Host resistance? SECURE aimed to increase our understanding of host resistance and the best way to use this resource.

8 SECURE (QLK5-CT-2002-01813) What is host resistance? Like us, plants and fungi have genes Genes control all processes of living things Genes control all processes of living things Some of these genes (resistance genes) help fight attack by diseases – fungi, viruses, bacteria. However, diseases also have genes (avirulence genes) which correspond and interact with those in the plant

9 SECURE (QLK5-CT-2002-01813) What is host resistance? - continued Interaction between specific corresponding resistance and avirulence genes, good for the plant: Plant recognises presence of fungus Plant recognises presence of fungus Resistance mechanisms prevent infection Resistance mechanisms prevent infection However, in the war of the genes, sometimes the plant resistance genes are overcome!

10 SECURE (QLK5-CT-2002-01813) What is host resistance? - continued The fungus mutates to loose the function of the avirulence gene No interaction with the plant resistance gene No interaction with the plant resistance gene The plant no longer recognises the presence of the fungus The plant no longer recognises the presence of the fungus No resistance response No resistance response Infection of the plant!! Infection of the plant!!

11 SECURE (QLK5-CT-2002-01813) The need for durable resistance Limited number of plant resistance genes can be used in breeding programmes Most are overcome in 3-5 years However, some resistance genes remain effective for 5-10 years – why? Durable resistance

12 SECURE (QLK5-CT-2002-01813) The need for durable resistance – contd Better understanding of interactions allows smart use of available resistance Allows development of breeding strategies to maximise durability of resistance. Oilseed rape flowers in springtime

13 SECURE (QLK5-CT-2002-01813) Aims of SECURE Develop a mechanistic model of the life cycle of Leptosphaeria maculans (pathogen) Study molecular mechanisms which generate virulent isolates of the pathogen Analyse effects of genetic background and environment on resistance durability Construct models and disseminate strategies for deployment of durable resistance

14 SECURE (QLK5-CT-2002-01813) Who benefits from SECURE People within the European Union Reduced pesticide input Reduced pesticide input Reduced environmental impact Reduced environmental impact Global agricultural industry Breeding of improved types of oilseed rape Breeding of improved types of oilseed rape Sustainable oilseed rape production Sustainable oilseed rape production Global scientific community Increased knowledge Increased knowledge Modelling of novel system Modelling of novel system

15 SECURE (QLK5-CT-2002-01813) Visit the website www.secure.rothamsted.ac.uk/

16 SECURE (QLK5-CT-2002-01813) Methods developed during SECURE Ascospore shower inoculation protocol

17 SECURE (QLK5-CT-2002-01813) Methods developed during SECURE Green-Fluorescent Protein expressing isolates of L. maculans developed a.Stem of oilseed rape cv. Darmor viewed under white light with visible necrosis at leaf scars of inoculated leaves. b.The same stem viewed under fluorescent light, showing hyphae of GFP-expressing transformed L. maculans isolate ME24 indicating initial infection of stem through the petiole

18 SECURE (QLK5-CT-2002-01813) Results from Workpackage 1 Development of a life cycle model for Leptosphaeria maculans Developed during the first two years (2003-04) Stepwise model Validated with data collected during SECURE Published in: Evans et al. (2007). Development and validation of a model to describe the progress phoma stem canker epidemics in England and France. Proceedings of the 12 th International Rapeseed Congress, Wuhan, China, 26-30 March 2007, 4: 161-164. Ascopores Latent period Petiole Canker development Phoma spot visible Canker severity

19 SECURE (QLK5-CT-2002-01813) Results from Workpackage 2 Effects of pathogen variation at Avr loci on durability of resistance Cloning and functional analysis studies done on effector genes AvrLm1 and AvrLm6 Three publications to date with more to come: Fudal I, Ross S, Gout L, Blaise F, Kuhn ML, Eckert MR, Cattolico L, Bernard- Samain S, Balesdent MH, Rouxel T (2007) Heterochromatin-like regions as ecological niches for avirulence genes in the Leptosphaeria maculans genome: Map-based cloning of AvrLm6. Molecular Plant-Microbe Interactions 20:459-470 Fudal I, Ross S, Gout L, Blaise F, Kuhn ML, Eckert MR, Cattolico L, Bernard- Samain S, Balesdent MH, Rouxel T (2007) Heterochromatin-like regions as ecological niches for avirulence genes in the Leptosphaeria maculans genome: Map-based cloning of AvrLm6. Molecular Plant-Microbe Interactions 20:459-470 Gout L, Fudal I, Kuhn ML, Blaise F, Eckert M, Cattolico L, Balesdent MH, Rouxel T (2006) Lost in the middle of nowhere: the AvrLm1 avirulence gene of the Dothideomycete Leptosphaeria maculans. Molecular Microbiology 60:67-80 Gout L, Fudal I, Kuhn ML, Blaise F, Eckert M, Cattolico L, Balesdent MH, Rouxel T (2006) Lost in the middle of nowhere: the AvrLm1 avirulence gene of the Dothideomycete Leptosphaeria maculans. Molecular Microbiology 60:67-80 Gout L, Kuhn ML, Vincenot L, Bernard-Samain S, Cattolico L, Barbetti M, Moreno- Rico O, Balesdent MH, Rouxel T (2007) Genome structure impacts molecular evolution at the AvrLm1 avirulence locus of the plant pathogen Leptosphaeria maculans. Environmental Microbiology 9:2978-2992 Gout L, Kuhn ML, Vincenot L, Bernard-Samain S, Cattolico L, Barbetti M, Moreno- Rico O, Balesdent MH, Rouxel T (2007) Genome structure impacts molecular evolution at the AvrLm1 avirulence locus of the plant pathogen Leptosphaeria maculans. Environmental Microbiology 9:2978-2992

20 SECURE (QLK5-CT-2002-01813) Results from Workpackage 2 continued Effects of pathogen variation at Avr loci on durability of resistance Fitness studies using Near Isogenic Isolates (NIIs) for AvrLm1/avrLm1, AvrLm4/avrLm4, AvrLm6/avrLm6 Ascospore shower inoculation method used Results suggested a fitness cost was associated with evolution from avirulence to virulence at both AvrLm1 and AvrLm4 loci. There was a difference in the strength of the effect Results for AvrLm4 work published in: Huang Y-J, Li Z-Q, Evans N, Rouxel T, Fitt BDL, Balesdent M-H (2006). Fitness cost associated with loss of the AvrLm4 avirulence function in Leptosphaeria maculans (phoma stem canker of oilseed rape). European Journal of Plant Pathology, 114: 77-89 Huang Y-J, Li Z-Q, Evans N, Rouxel T, Fitt BDL, Balesdent M-H (2006). Fitness cost associated with loss of the AvrLm4 avirulence function in Leptosphaeria maculans (phoma stem canker of oilseed rape). European Journal of Plant Pathology, 114: 77-89

21 SECURE (QLK5-CT-2002-01813) Results from Workpackage 3 Race structure of Leptosphaeria maculans population characterised across Europe Stachowiak et al., 2006. Frequency of Avirulence Alleles in Field Populations of Leptosphaeria maculans in Europe. European Journal of Plant Pathology 114: 67-75.

22 SECURE (QLK5-CT-2002-01813) Results from Workpackage 3 continued Multi-site evaluation of resistance (2002-2005):

23 SECURE (QLK5-CT-2002-01813) Results from Workpackage 3 continued Multi-site evaluation of resistance (2002-2005): CultivarPhom) stem canker %inc Phoma stem canker G2 index Phoma stem lesions %inc Phoma stem lesion G2 index Phoma leaf lesions %inc Phoma leaf lesion % area Apex64.62.9468.71.9564.52.09 Darmor59.52.1352.61.3460.02.02 Darmor-MX23.80.6950.81.457.30.16 Escort62.32.9367.51.8658.51.60 Eurol73.43.5469.62.6160.91.70 Eurol-MX31.21.1680.23.699.60.19 Falcon63.32.9066.32.1653.01.44 Samourai78.04.0674.22.7063.21.95 Shogun80.34.5648.91.4868.42.22 Capitol77.73.4987.33.95*63.01.50** Sed (average)2.080.1473.810.1952.720.218 F test<0.001 *2005 data only **2003 and 2005 data only

24 SECURE (QLK5-CT-2002-01813) Results from Workpackage 3 continued Darmor MX (containg the Rlm6 resistance gene used to investigate effect of temperature and leaf wetness on infection. Rlm6 resistance found to be temperature sensitive Results published in: Huang Y-J, Evans N, Li Z-Q, Eckert M, Chevre A-M, Renard M, Fitt BDL (2006). Temperature and leaf wetness duration affect phenotypic expression of Rlm6-mediated resistance to Leptosphaeria maculans in Brassica napus. New Phytologist, 170, 129-141 Symptoms on the leaves of Brassica napus Darmor (lacking Rlm6) and DarmorMX (carrying Rlm6) inoculated with ascospores (without wounding, a,b,c,d,e; with 48 h wetness) or conidia (after wounding, f,g; with 72 h wetness) of Leptosphaeria maculans carrying the effector gene AvrLm6. (a) Large grey lesions on Darmor 11 d after inoculation at 15°C; (b) no visible symptoms on DarmorMX 11 d after inoculation at 15°C; (c) small dark spots (black arrows) and green islands (white arrows) on DarmorMX 18 d after inoculation at 15°C; (d) small dark spots (arrows) on DarmorMX 11 d after inoculation at 20°C; (e) large grey lesions on DarmorMX 16 d after inoculation at 25°C; (f) large grey lesions on Darmor 16 d after inoculation at 25°C; (g) large grey lesions on DarmorMX 16 d after inoculation at 25°C. Bar, 5 mm

25 SECURE (QLK5-CT-2002-01813) Results from Workpackage 3 continued GFP (Green Fluorescent Protein) – expressing isolates of L. maculans developed GFP – expressing isolates used to These results were published in the following peer- reviewed publication: Huang et al., 2009. Quantitative resistance to symptomless growth of Leptosphaeria maculans (phoma stem canker) in Brassica napus (oilseed rape). Plant Pathology, 58, 314-323. a) Stem of oilseed rape cv. Darmor viewed under white light with visible necrosis at leaf scars of inoculated leaves. b) the same stem viewed under fluorescent light, showing hyphae of GFP-expressing transformed L. maculansisolate ME24 indicating initial infection of stem through the petiole.

26 SECURE (QLK5-CT-2002-01813) Results from Workpackage 4 Modelling investigated the merits of pyramiding vs. sequential deployment of resistance genes?

27 SECURE (QLK5-CT-2002-01813) Pyramiding vs. sequential deployment of resistance genes? Conclusions: Fitness cost of virulence high – Pyramid resistance genes Fitness cost of virulence low – Sequential deployment more beneficial

28 SECURE (QLK5-CT-2002-01813) SECURE For more details on the SECURE project, please see the website: www.secure.rothamsted.ac.uk

29 SECURE (QLK5-CT-2002-01813) SECURE consortium


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