Marker-Assisted Breeding for Fusarium Wilt ... - SaskCanola

Marker-Assisted Breeding for Fusarium Wilt Resistance in Canola
Mr. Ralph Lange, Alberta Research Council, Vegreville, AB,
S. Kuzmiez, Agriculture and Agri-Food Canada, Saskatoon, SK,
S. Rimmer, Agriculture and Agri-Food Canada, Saskatoon, SK
Project Code: CARP 2005-10
Final Report: June 2009
Fusarium wilt resistance in Brassica napus was found to be conferred by a single
dominant gene, the A-genome. This means that B. rapa and B. oleracea may be
sources of resistance to fusarium wilt available to B. napus breeders. Combining
resistances could be used to increase the longevity of resistance to Fusarium wilt in B.
napus.
Fusarium wilt (FW) of canola, caused by the pathogen Fusarium oxysporum, results in
severe yield losses of canola. However, yield losses due to FW can be eliminated through
the use of resistant cultivars. Genetic resistance is the most cost-effective and probably
the only effective method of controlling FW. Plant breeders could theoretically eliminate
susceptible genotypes from their current and future simply by screening out susceptibility
to FW early in crossing programs.
In comparisons of susceptible and resistant Brassica napus genotypes in field trials at
nine locations in western Canada, the mean yield of the least-affected cultivar was 16 %
higher than the most severely affected cultivar. Yield improvement due to disease
resistance increased to 75% when the least and most severely affected cultivars were
compared at the site with the greatest disease pressure. FW-susceptible cultivars or
breeding lines can be identified using growth chamber and field screening techniques.
Use of these techniques has allowed plant breeders to identify susceptible germplasm in
breeding programs.
A fusarium-wilt infected field planted to a susceptible variety
near Viking.
Source: AITF
Genetic markers can be used to
differentiate plants that carry a desired trait
(such as FW resistance) from those that do
not. Resistance to FW has not been
associated to molecular markers in B.
napus, although this has been done for
vascular FW of other crop species.
Knowledge of the mode of inheritance
would improve the ability of plant breeders
to manipulate the FW-resistance trait.
Ideally, FW resistance would be linked to
DNA-based genetic markers. Markerassisted
selection would allow breeders to

directly infer the genotype of very young plants, and avoid time delays caused by
phenotype testing, and simultaneously avoid confounding effects of genotype x
environment interactions.
The objectives of this project were to identify and characterize the mode of inheritance of
the FW-resistant phenotype in B. napus, to determine the number of genes associated
with resistance and to identify microsatellite markers that are linked with those genes.
Phenotype tests of the parental genotypes confirmed that SP Banner and DH12075 were
resistant, and Canterra 1604 was susceptible to FW, confirming that subsequently-derived
mapping populations were the progeny of crosses between resistant and susceptible
plants.
Segregation between F3 lines from
reciprocal matings fit 3:1
(Resistant:susceptible) segregation ratios
individually and when combined,
suggesting that resistance in B. napus cv.
DH12075 is controlled by a single
dominant gene for resistance to FW.
Assessment of the A-genome indicated that
microsatellite markers sR0404 and sR9448
were associated with the resistant
phenotype. On this basis, FW-resistance in
B. napus was associated with a single
locus mapping to A-3 linkage group.
Genetic analysis of FW resistance in B.
In comparison, a resistant variety field located immediately
adjacent to the affected field near Viking.
Source: AITF
napus has not been conducted previously, but resistance has been associated with B.
rapa, which is ancestral to B. napus. Resistance to F. oxysporum has been characterized
in B. oleracea, the other B. napus ancestor, suggesting that additional, as-yet unidentified
resistance to FW may be available on the B. napus C-genome. This means that multiple
sources of resistance may be available to canola breeders, either within B. napus or via
interspecific crosses between B. oleracea and B. rapa. Combining resistances could be
used to increase the longevity of resistance to FW.
The results of this study will allow member-organizations of the Microsatellite Marker
Consortium to screen accessions for resistance/susceptibility to FW. The consortium
includes most of the oilseed Brassica napus breeding organizations active in the North
American marketplace. Currently, breeding organizations either screen selections in
naturally-infested field nurseries, or test for resistance in controlled environment tests.
Use of the markers would allow these organizations to screen large numbers of
accessions, and also avoid much of the field or controlled environment screening
phenotype testing that is currently necessary.

Scientific Publications
Lange, R.; Rimmer, S. R.; Lydiate, D.; Kuzmicz, S.; Goßmann, M. ; Büttner, C. 2010.
Linkage of Resistance to Fusarium Wilt (Fusarium oxysporum) in Spring Rapeseed
(Brassica napus) with Microsatellite Markers. 57. Deutsche
Pflanzenschutztagung, Berlin, Germany, September 6 – 9, 2010