Elements of disease management: breeding for resistance and influence of cultivation methods Based on lecture presentations by Helge Skinnes and Morten Lillemo PJH300 2017 Tittel på presentasjon Norwegian University of Life Sciences 1 Elements of disease management: breeding for resistance and influence of cultivation methods: outline • ( list of Norwegian, English and scientific names of some major cereal fungi diseases) • The disease triangle • Types of disease resistance Principles • Examples of diseases in cereals Elements/major types – air-borne pathogens – residue-borne pathogens – seed-borne pathogens • Disease control strategies Mandatory for JPH300-2017 – Variety mixtures – Integrated control – Risk assessment 2 Diseases in Cereals SYKDOMMER – diseases in cereals. • • BIOTROFE- biotrophic • MJØLDOGG- Mildew (Blumeria graminis) • SVARTRUST – stem rust, black rust (Puccinia graminis) • GULRUST- Yellow rust (Puccinia striiformis) • NEKROTROFE- necrotrophic • AKSPRIKK- Glume blotch (Stagnospora nodorum) • BLADPRIKK- Leaf blotch (Mycosphaerella graminicola) (Mycosphaerella graminicola) • BYGG BRUNFLEKK- Net blotch (Pyrenophora teres (Drechslera Teres)) • HAVRE BRUNFLEKK- Leaf blotch (Drechslera avenae) • GRÅ ØYEFLEKK- Scald (Rynchosporium secalis) • FUSARIUM- (Fusarium spp.) Tittel på presentasjon Norwegian University of Life Sciences 3 SYKDOMMER – diseases in cereals. • • • FOTSYKE- foot rot disease • ROTDREPER- Take all (Gaumanomyces graminis) • STRÅKNEKKER- Eyespot/strawbreaker (Pseudocercosporella herpotrichoides) • • FRØ- OVERFØRTE – seed- borne • STRIPESYKE- Barley stripe (Drechslera graminea) • DEKKET SOT- Covered smut (Ustilago hordei) • NAKEN SOT- Loose smut (Ustilago nuda) • STINKSOT- Common bunt (Tilletia caries) • DVERGSTINKSOT- Dwarf bunt (Tilletia contraversa) • KARNAL BUNT- Carnal bunt (Tilletia indica) • • OVERVINTRINGS SOPPER – snow moulds • SNØMUGG- Pink snow mould (Microdocium nivale) • TRÅDKØLLE- Speckled snow mould (Typhula ishikariensis) • STORKNOLLET RÅTESOPP- Sclerotinia snow mould (Sclerotinia borealis). https://www.plantevernleksikonet.no/ Tittel på presentasjon Norwegian University of Life Sciences 4 Effect of cropping system on severity of cereal pathogens. Cropping system Dispersion by Epidemic Seed Plant pathogens debris Cereals after cereals and/ ??? or with reduced tillage Conventional with ??? rotation Conventional winter ??? wheat Ecological with rotation ??? Organic Cereals after ??? cereals The disease triangle Disease Favourable environment • Epidemic is the result of an interaction between a virulent pathogen on a susceptible host in an environment that favors the pathogen. 6 Diseases in Cereals Disease resistance • Most plants are resistant to most pathogens • Disease is an exception! • What causes this exception is the pathogen’s ability to overcome resistance mechanisms in the plant • Two types of resistance: –Race specific –Race non-specific 7 Diseases in Cereals Race specific resistance • Based on single genes • Gene-for-gene relationship • Often complete protection • Popular among plant breeders –Easy to select for –Simple genetics –Appealing phenotype 8 Diseases in Cereals Race specific resistance • However,… –Based on the plant’s ability to detect a single effector molecule from the pathogen –A single mutation in the pathogen can render the plants completely susceptible • Result: –Short durability 9 Diseases in Cereals Airborne pathogens with high evolutionary potential • Powdery mildew, Blumeria graminis • Stem rust, Puccinia graminis • Leaf rust (brown rust), P. triticina • Stripe rust (yellow rust), P. striiformis • Average lifetime of race-specific resistance genes: 3-5 years https://www.plantevernleksikonet.no/ https://www.plantevernleksikonet.no/l/oppslag/1235/ 10 Diseases in Cereals • Caused by Blumeria Powdery mildew graminis • Different formae speciales attack wheat, barley, oats and rye • Colonize epidermal cells of the leaf • Obligate biotrophic pathogen that only survives on living plant material 11 Diseases in Cereals Powdery mildew life cycle Diseases in Cereals 12 Cleistothecium: globose, completely closed ascocarp, filled with asci that contain 4 or 8 ascospores Powdery mildew on wheat in Norway Hamar area: – Stable snow cover – Sexual reproduction at the end of the season Hamar – Local adapted populations of B. graminis f.sp. tritici survive on winter wheat Oslo area: Oslo – Unstable snow cover – New inoculum from Southern Sweden and Denmark every year Short durability of race- specific resistance Wind direction Skinnes (2002) 13 Diseases in Cereals Recent spring wheat varieties in Norway • Polkka – Released 1992 – susceptible 1992 •Brakar – Released 1995 – susceptible 1996 •Avle – Released 1996 – susceptible 1999 • Zebra – Released 2001 – susceptible 2003 •Bjarne – Released 2002 – susceptible 2004 14 Diseases in Cereals Why short durability • Airborne pathogens – spores can be dispersed over hundreds of km • Short generation time (Polycycle) • Big population size • Sexual reproduction • Same resistance gene deployed in varieties over a large area • Survival of the pathogen between growing seasons 15 Diseases in Cereals Race non-specific resistance • Also called partial or horizontal resistance • Quantitative inheritance – based on several genes with additive effects • Equal effects against all races of the pathogen • Only partially effective, but retards disease development • High durability 16 Diseases in Cereals Genetics of partial resistance 100 Susceptible 1 to 2 minor genes % rust 2 to 3 minor genes 4 to 5 minor genes 0 Time 17 Diseases in Cereals Race specific vs partial resistance Severity (%) of powdery mildew in European spring wheat ringtest 2001: 30 Partial resistance can be highly effective 25 against powdery mildew in wheat Germany 20 France Norway 1 15 Norway 2 10 Finland Switzerland 5 0 NK98523 Naxos 18 Diseases in Cereals Partial resistance is based on different mechanisms Naxos Saar NK93602 19 Diseases in Cereals Stripe rust on wheat in UK Cultivar Genes Released Susceptible Rothwell Perdix Yr1, (Yr2, Yr6) 1964 1966 Maris Ranger Yr3a, Yr4a, Yr6 1968 1969 Talent Yr7 1973 (planned) 1972 Clement Yr2, Yr9 1975 1975 Stetson Yr1, Yr9 1983 1983 Hornet Yr2, Yr6, Yr9 1987 1988 Brigadier Yr9, Yr17 1993 1996 Boyd (2005) 20 Diseases in Cereals https://www.plantevernleksikonet.no/l/oppslag/1235/ http://www.cpm-magazine.co.uk/2017/01/07/yellow-rust-quest-quell-shapeshifter/ Last accessed 31/10/2017 Tittel på presentasjon Norwegian University of Life Sciences 21 http://www.cpm-magazine.co.uk/2017/01/07/yellow-rust-quest-quell-shapeshifter/ Last accessed 31/10/2017 Tittel på presentasjon Norwegian University of Life Sciences 22 Stem rust • Caused by Puccinia graminis • Historically the most important disease on wheat in terms of damage • Can also affect wheat, barley, oats, and rye • Barberry important as alternative host • Severe yield losses in Europe before the 1900s • Big epidemics in USA and Canada in 1916 and 1935 23 Diseases in Cereals Stem Rust 24 Diseases in Cereals Tittel på presentasjon Norwegian University of Life Sciences 25 Stem rust kept under control Erradication of Barberry (Berberis vulgaris) Breeding of resistant cultivars – partial resistance conferred by Sr2 and other genes – race-specific resistance – Sr31 on the 1B/1R translocation effective for several decades No serious outbreak in Europe and North America since the 1950s 26 Diseases in Cereals Ug99 – a new threat to global wheat production • Most wheat cultivars across the world have resistance based on a single gene – Sr31 • New virulence to this gene appeared in Uganda in 1999 and is now spreading rapidly An epidemic of stem rust on wheat caused by race TTKSK (e.g. isolate Ug99) is currently spreading across Africa, and the Middle East Wikipedia last assessed 24.10.2016 27 Diseases in Cereals https://en.wikipedia.org/wiki/Ug99 Dissemination of resistant cultivars is urgent! 28 Diseases in Cereals La Tittel på presentasjon Norwegian University of Life Sciences 29 Last accessed 31/1072017 Residue-borne diseases • All cereals: –Fusarium Head Blight, Fusarium spp. • Wheat: –Septoria Leaf Blotch, Septoria tritici –Stagonospora Glume Blotch, Stagonospora nodorum •Barley: –Barley scald, Rhynchosporioum secalis –Net blotch, Pyrenophora teres 30 Diseases in Cereals Fusarium Head Blight (FHB) • Caused by Fusarium graminearum, F. culmorum and other Fusarium spp. • A major disease problem in all cereals • Leads to accumulation of mycotoxins in the grain 31 DETTE ER TITTELEN PÅ PRESENTASJONEN Fusarium Head Blight (FHB) Mycotoxins 32 DETTE ER TITTELEN PÅ PRESENTASJONEN Fusarium Head Blight (FHB) • Has become a major disease worldwide since the 1990s. • Heavy epidemics in the Mid West of the USA (Minnesota, North Dakota) coincided with the introduction of reduced tillage –pathogen survives in the plant residues • Other factors that promote FHB –cultivation of susceptible wheat and barley varieties –crop rotation with maize –warm and humid weather –lodging https://www.plantevernleksikonet.no/l/oppslag/1239/ 33 DETTE ER TITTELEN PÅ PRESENTASJONEN FHB in Norway • Pathogen population has changed (I. S. Hofgaard, Bioforsk) –F. avenaceum and F. culmorum dominated in the 1990s –F. graminearum now the dominating species • Worst problems in wheat and oats 34 DETTE ER TITTELEN PÅ PRESENTASJONEN Resistance breeding for FHB • No complete resistance • Resistance is quantitative and pathogen non-specific • Field testing is expensive, labour-intensive and not very reliable • Marker-assisted selection