Genetic mapping of the Leptosphaeria maculans avirulence gene corresponding to the LepR1 resistance gene of Brassica napus

• Published in: Theoretical and applied genetics 2012-02, Vol.124 (3), p.505-513
• Main Authors: Ghanbarnia, Kaveh, Lydiate, Derek J., Rimmer, S. Roger, Li, Genyi, Kutcher, H. Randy, Larkan, Nicholas J., McVetty, Peter B. E., Fernando, W. G. Dilantha
• Format: Article
• Language: English
• Subjects: Agriculture; Analysis; Ascomycota; Ascomycota - genetics; Ascomycota - pathogenicity; Biochemistry; Biomedical and Life Sciences; Biotechnology; Brassica napus; Brassica napus - genetics; Brassica napus - microbiology; Chromosome Mapping; Crosses, Genetic; Disease Resistance - genetics; DNA Primers - genetics; Fungi; Genes; Genes, Fungal - genetics; Genes, Plant - genetics; Genetic aspects; Genetic Markers - genetics; Genetics; Genomics; Leptosphaeria maculans; Life Sciences; Original Paper; Physiological aspects; Plant Biochemistry; Plant Breeding/Biotechnology; Plant Diseases - microbiology; Plant Genetics and Genomics; Plant immunology; Rape (Plant); Segregation; Virulence - genetics
• ISSN: 0040-5752; 1432-2242
• DOI: 10.1007/s00122-011-1724-3

AvrLepR1 of the fungal pathogen Leptosphaeria maculans is the avirulence gene that corresponds to Brassica LepR1 , a plant gene controlling dominant, race-specific resistance to this pathogen. An in vitro cross between the virulent L. maculans isolate, 87-41, and the avirulent isolate, 99-56, was performed in order to map the AvrLepR1 gene. The disease reactions of the 94 of the resulting F 1 progenies were tested on the canola line ddm-12-6s-1, which carries LepR1 . There were 44 avirulent progenies and 50 virulent progenies suggesting a 1:1 segregation ratio and that the avirulence of 99-56 on ddm-12-6s-1 is controlled by a single gene. Tetrad analysis also indicated a 1:1 segregation ratio. The AvrLepR1 gene was positioned on a genetic map of L. maculans relative to 259 sequence-related amplified polymorphism (SRAP) markers, two cloned avirulence genes ( AvrLm1 and AvrLm4 - 7 ) and the mating type locus ( MAT1 ). The genetic map consisted of 36 linkage groups, ranging in size from 13.1 to 163.7 cM, and spanned a total of 2,076.4 cM. The AvrLepR1 locus was mapped to linkage group 4, in the 13.1 cM interval flanked by the SRAP markers SBG49-110 and FT161-223. The AvrLm4 - 7 locus was also positioned on linkage group 4, close to but distinct from the AvrLepR1 locus, in the 5.4 cM interval flanked by FT161-223 and P1314-300. This work will make possible the further characterization and map-based cloning of AvrLepR1 . A combination of genetic mapping and pathogenicity tests demonstrated that AvrLepR1 is different from each of the L. maculans avirulence genes that have been characterized previously.