Identification and mapping of a novel blackleg resistance locus LepR4 in the progenies from Brassica napus×B.rapa subsp. sylvestris

摘要

Two blackleg resistant lines, 16S and 61446, were developed though inter-specific hybridization between Brassica napus and B. rapa subsp. sylvestris and backcrossing to B. napus. Classical genetic analysis showed that a single recessive gene in each line contributed to resistance to L. maculans and the resistance genes were either allelic or the same. This locus was mapped to B.napus linkage group N6, flanked by microsatellite markers sN2189b and sR9571a using a total of 147 plants in BC1 populations from crosses 61446×(61446×PSA12) and 16S×(16S×PSA12). This new resistance gene locus was designated LepR4. The two lines were tested for cotyledon resistance to a wide range of isolates and evaluated for stem canker resistance in blackleg nurseries. Results indicated that 16S was highly resistant to most isolates tested and showed a high level of stem canker resistance in the blackleg nurseries. The line 61446 was only resistant to a few isolates and was susceptible in the blackleg nurseries,indicating that these two lines probably carry different resistance alleles at the LepR4 locus.