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

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.