Authors: Yu, Fengqun; Lydiate, Derek J.; Rimmer, S. R.

Source: Genome, Volume 51, Number 1, January 2008 , pp. 64-72(9)

Publisher: NRC Research Press

Abstract:

The spectrum of resistance to isolates of Leptosphaeria maculans and the map location of a new blackleg resistance gene found in the canola cultivar Brassica napus `Surpass 400' are described. Two blackleg resistance genes, LepR1 and LepR2, from B. rapa subsp. sylvestris and introgressed in B. napus were identified previously. `Surpass 400' also has blackleg resistance introgressed from B. rapa subsp. sylvestris. Using 31 diverse isolates of L. maculans, the disease reaction of `Surpass 400' was compared with those of the resistant breeding lines AD9 (which contains LepR1), AD49 (which contains LepR2), and MC1-8 (which contains both LepR1 and LepR2). The disease reaction on `Surpass 400' was different from those observed on AD9 and MC1-8, indicating that `Surpass 400' carries neither LepR1 nor both LepR1 and LepR2 in combination. Disease reactions of `Surpass 400' to most of the isolates tested were indistinguishable from those of AD49, which suggested `Surpass 400' might contain LepR2 or a similar resistance gene. Classical genetic analysis of F<sub>1</sub> and BC<sub>1</sub> plants showed that a dominant allele conferred resistance to isolates of L. maculans in `Surpass 400'. The resistance gene, which mapped to B. napus linkage group N10 in an interval of 2.9 cM flanked by microsatellite markers sR12281a and sN2428Rb and 11.7 cM below LepR2, was designated LepR3. A 9 cM region of the B. napus genome containing LepR3 was found to be syntenic with a segment of Arabidopsis chromosome 5.

Le spectre de résistance à divers isolats du Leptosphaeria maculans et l'emplacement chromosomique d'un nouveau gène de résistance à la jambe noire, identifié chez le Brassica napus `Surpass 400', sont décrits. Deux gènes de résistance, LepR1 et LepR2, provenant du B. rapa subsp. sylvestris et introgressés chez le B. napus ont été identifiés précédemment. Le cultivar `Surpass 400' possède également une résistance introduite à partir du B. rapa subsp. sylvestris. À l'aide de 31 isolats du L. maculans, la réaction de `Surpass 400' a été comparée avec celle des lignées résistantes AD9 (possédant le gène LepR1), AD49 (possédant le gène LepR2) et MC1-8 (contenant les gènes LepR1 et LepR2). La résistance observée chez `Surpass 400' différait de celle observée tant chez AD9 que chez MC1-8, ce qui suggère que ce cultivar ne porte ni LepR1 seul, ni LepR1 et LepR2 ensemble. Les symptômes chez `Surpass 400' vis-à-vis la majorité des isolats étaient identiques à ceux observés chez AD49, ce qui suggère que `Surpass 400' pourrait posséder LepR2 ou un gène de résistance semblable. Une analyse génétique classique sur des plantes F₁ et BC₁ a montré qu'un allèle dominant conférait la résistance aux isolats du L. maculans chez `Surpass 400'. Ce gène de résistance qui a été assigné au groupe de liaison N10 du B. napus, dans un intervalle de 2,9 cM (entre les microsatellites sR12281a et sN2428Rb) et 11,7 cM sous la position de LepR2, a été nommé LepR3. Une région de 9 cM du génome du B. napus contenant LepR3 s'est avérée synténique avec un segment du chromosome 5 chez Arabidopsis.

Document Type: Research article

Publication date: 2008-01-01

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• From its inception in 1957, this international cytogenetics journal has catered to the research areas of the members of the Genetics Society of Canada; traditionally, these have included agriculture, entomology, genetics/cytogenetics, and evolutionary mechanisms. The contents of the journal have evolved as contributors developed new technologies and interests. A 20-member Editorial Board is composed of scientists from around the world. Reviews and commentary from respected experts are often featured.
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