New Clubroot Strains in Canola - AlbertaDepartment/deptdocs.nsf/all/crop15631/$FILE/... · Canola...
Transcript of New Clubroot Strains in Canola - AlbertaDepartment/deptdocs.nsf/all/crop15631/$FILE/... · Canola...
Clubroot Update
Jan 19/2016Red Deer
Photo courtesy of Dr. Ron Howard
J.P. Tewari
Lifecycle of Clubroot
• Strains of clubroot can overcome resistance. Over-reliance on resistant varieties in short rotationswill increase the risk of build up of various strains and should be avoided.
History teaches us but do we listen?
• Clubroot resistant cabbage in USA becomes susceptible (Seaman, U of Wisconsin,1960)
• Chinese cabbage clubroot resistance overcome in Australia (Donald et al., 2006)
• CR Chinese cabbage in Japan overcome about 10 years after introduction (Tanaka and Ito, 2013).
Canola Clubroot Resistance
• Most likely all western Canada current resistance in canola is from the European winter oilseed variety ‘Mendel’
Alberta Situation
Clubroot in Alberta 2003 to 2015
• First canola field reported in AB in 2003
• Over 2000 known fields infested in AB
• Fields in AB have been reported to have > 10m spores/gram in soil
• New strain of clubroot• 5x….
• This new strain was tested against all existing CR varieties• Most cases severity > 90%
2013 Situation
• Target survey on CR cultivars
• 16 fields of pathogen shift
• In addition to 5x, 9 distinct pathotypevariants
2014 Situation
Strelkov & Cao, unpublished
• Survey conducted on CR fields
• Found 32 new ‘suspicious’ fields in Central AB
• Samples to be pathotyped at UofA
2015 Survey
Classification of New Strains of Plasmodiophora brassicae: A Preliminary Assessment
S.E. Strelkov, S.F. Hwang, V.P. Manolii, and T. Cao
Pathogen
S S S R S
Pathogen isolates are grouped into strains based on the symptoms they
cause on a defined group of hosts
‘Pathotype 5x’Host variety Pathotype
3 5 5xJersey Queen (cabbage) + - -Badger Shipper (cabbage) - - -Laurentian (rutabaga) + - -Wilhemsburger (rutabaga) - - -Canadian ‘clubroot resistant’ canola
- - +
Pathotype designations as defined on system of Williams (1966)
Genotype
Field population
CDCN#2CDCN#4 CDCN#6 CDCS F1‐14 F175‐14 F3‐14
F183‐14
F184‐14
F185‐14
F186‐14
F187‐14
F188‐14
F189‐14 F331‐14 F41‐14
ECD 02 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐
ECD 05 + + + + + + + + + + + + + + + +
ECD 06 + + ‐ ‐ + + + + + + + + + + + +
ECD 08 + + + + + + + + + + + + + + + +
ECD 09 + + ‐ ‐ + + + + + + + + + + + +
ECD 10 ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐
ECD 11 ‐ ‐ ‐ ‐ ‐ ‐ ‐ + ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐
ECD 13 ‐ + ‐ + + + + + + + + ‐ ‐ + + +
Brutor + + + + + + + + + + + + + + + +
Laurentian ‐ + ‐ ‐ + ‐ + + + + + + + + + +
Mendel ‐ ‐ ‐ ‐ ‐ + + + + + + ‐ ‐ + + ‐
Westar + + + + + + + + + + + + + + + +
45H29 ‐ ‐ + + + + + + + + + + + + + ‐
Pathotype designation:CCD (temporary) A B C D E F G H G G G I I G G B
Williams, 1966 5 3 5 6 3 6 3 2 3 3 3 8 8 3 3 3
Some et al., 1996 P2 P2 P3 P3 P2 P2 P2 P2 P2 P2 P2 P2 P2 P2 P2 P2
Nine distinct virulence phenotypes detected
• One variant of pathotype 3 was most common: 6 of 16 populations
• One variant of pathotype 2 also highly virulent (11 of 13 differentials)
Words of Caution
• Novel strains tested are ‘field’ populations
• May represent mixture of pathotypes – Masking of rarer strains– Antagonistic/synergistic
interactions
• Analysis of single-spore will be important
Characterizing P5x populations with B. napus lines at AAFC, Saskatoon
B. napus LG-01 LG-02 LG-03
BN-E-06 R S R
BN-E-08 S S S
BN-E-09 R R R
BN-I-01 R S S
Differential reactions were found in a set of B. napus lines at AAFC.
There are at least 3 races in P5x populations.
LG-2 is the most aggressive one.
BN-E-09 is resistant to all.
Clubroot Severity in B-Tolerant Lines
0
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Seve
rity
(DSI
)
UntreatedTreated
A fungal endophyte that induces resistance to clubroot in canola
y = 24.3x2 - 66.8x + 52R2 = 0.86
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0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Clu
broo
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Colonization of canola roots by Hc (ng/g)
qPCR