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Co-localisation of the blackleg resistance genes Rlm2 and LepR3 on Brassica napus chromosome A10.

Larkan NJ, Lydiate DJ, Yu F, Rimmer SR, Borhan MH - BMC Plant Biol. (2014)

Bottom Line: Molecular markers tightly linked to the gene were developed for use in mapping the resistance locus and defining the physical interval in B. napus.Rlm2 was localised to a 5.8 cM interval corresponding to approximately 873 kb of the B. napus chromosome A10.The recently-cloned B. napus R-gene, LepR3, occupies the same region of A10 as Rlm2 and analysis of the putative B. napus and B. rapa genes in the homologous region identified several additional candidate defense-related genes that may control Rlm2 function.

View Article: PubMed Central - PubMed

ABSTRACT

Background: The protection of canola (Brassica napus) crops against blackleg disease, caused by the fungal pathogen Leptosphaeria maculans, is largely mediated by race-specific resistance genes (R-genes). While many R-genes effective against blackleg disease have been identified in Brassica species, information of the precise genomic locations of the genes is limited.

Results: In this study, the Rlm2 gene for resistance to blackleg, located on chromosome A10 of the B. napus cultivar 'Glacier', was targeted for fine mapping. Molecular markers tightly linked to the gene were developed for use in mapping the resistance locus and defining the physical interval in B. napus. Rlm2 was localised to a 5.8 cM interval corresponding to approximately 873 kb of the B. napus chromosome A10.

Conclusion: The recently-cloned B. napus R-gene, LepR3, occupies the same region of A10 as Rlm2 and analysis of the putative B. napus and B. rapa genes in the homologous region identified several additional candidate defense-related genes that may control Rlm2 function.

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Related in: MedlinePlus

Interaction ofL. maculansisolate ‘165’ with differential lines ofB. napus. Cotyledons of seven B. napus lines pictured at 14-day post-inoculation. Lines containing Rlm2 (‘Glacier DH24287’ – Rlm2, Rlm3; ‘Tapidor DH’ – Rlm2) showed typical hypersensitive response and restriction of lesions while lines absent Rlm2 (‘Topas’ and ‘Topas DH16516’ – no blackleg resistance; ‘Quantum’- Rlm3; ‘Columbus’ – Rlm1, Rlm3; ‘NLA8-2’ – LepR3) were fully susceptible to infection.
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Fig1: Interaction ofL. maculansisolate ‘165’ with differential lines ofB. napus. Cotyledons of seven B. napus lines pictured at 14-day post-inoculation. Lines containing Rlm2 (‘Glacier DH24287’ – Rlm2, Rlm3; ‘Tapidor DH’ – Rlm2) showed typical hypersensitive response and restriction of lesions while lines absent Rlm2 (‘Topas’ and ‘Topas DH16516’ – no blackleg resistance; ‘Quantum’- Rlm3; ‘Columbus’ – Rlm1, Rlm3; ‘NLA8-2’ – LepR3) were fully susceptible to infection.

Mentions: The L. maculans isolate ‘165’ was used to inoculate 12 seedlings of each parental line used to construct the BC1F1 population. Infection with the isolate resulted in test scores between 7 and 9 on ‘Topas’ (average score 7.7) and scores of 2 to 5 on ‘Glacier DH24287’ (average score 2.5). Further tests using additional control B. napus lines showed ‘165’ was avirulent on the Rlm2 line ‘Tapidor DH’ (2.1) and virulent on the Rlm3 variety ‘Quantum’ (9.0), the Rlm1/Rlm3 variety ‘Columbus’ (8.9), ‘Topas DH16516’ (9.0) and the Topas DH16516:LepR3 transgenic line ‘NLA8-2’ (9.0). These results confirmed the “avrLm1, AvrLm2, avrLm3” pathotype of the isolate (Figure 1).Figure 1


Co-localisation of the blackleg resistance genes Rlm2 and LepR3 on Brassica napus chromosome A10.

Larkan NJ, Lydiate DJ, Yu F, Rimmer SR, Borhan MH - BMC Plant Biol. (2014)

Interaction ofL. maculansisolate ‘165’ with differential lines ofB. napus. Cotyledons of seven B. napus lines pictured at 14-day post-inoculation. Lines containing Rlm2 (‘Glacier DH24287’ – Rlm2, Rlm3; ‘Tapidor DH’ – Rlm2) showed typical hypersensitive response and restriction of lesions while lines absent Rlm2 (‘Topas’ and ‘Topas DH16516’ – no blackleg resistance; ‘Quantum’- Rlm3; ‘Columbus’ – Rlm1, Rlm3; ‘NLA8-2’ – LepR3) were fully susceptible to infection.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4302512&req=5

Fig1: Interaction ofL. maculansisolate ‘165’ with differential lines ofB. napus. Cotyledons of seven B. napus lines pictured at 14-day post-inoculation. Lines containing Rlm2 (‘Glacier DH24287’ – Rlm2, Rlm3; ‘Tapidor DH’ – Rlm2) showed typical hypersensitive response and restriction of lesions while lines absent Rlm2 (‘Topas’ and ‘Topas DH16516’ – no blackleg resistance; ‘Quantum’- Rlm3; ‘Columbus’ – Rlm1, Rlm3; ‘NLA8-2’ – LepR3) were fully susceptible to infection.
Mentions: The L. maculans isolate ‘165’ was used to inoculate 12 seedlings of each parental line used to construct the BC1F1 population. Infection with the isolate resulted in test scores between 7 and 9 on ‘Topas’ (average score 7.7) and scores of 2 to 5 on ‘Glacier DH24287’ (average score 2.5). Further tests using additional control B. napus lines showed ‘165’ was avirulent on the Rlm2 line ‘Tapidor DH’ (2.1) and virulent on the Rlm3 variety ‘Quantum’ (9.0), the Rlm1/Rlm3 variety ‘Columbus’ (8.9), ‘Topas DH16516’ (9.0) and the Topas DH16516:LepR3 transgenic line ‘NLA8-2’ (9.0). These results confirmed the “avrLm1, AvrLm2, avrLm3” pathotype of the isolate (Figure 1).Figure 1

Bottom Line: Molecular markers tightly linked to the gene were developed for use in mapping the resistance locus and defining the physical interval in B. napus.Rlm2 was localised to a 5.8 cM interval corresponding to approximately 873 kb of the B. napus chromosome A10.The recently-cloned B. napus R-gene, LepR3, occupies the same region of A10 as Rlm2 and analysis of the putative B. napus and B. rapa genes in the homologous region identified several additional candidate defense-related genes that may control Rlm2 function.

View Article: PubMed Central - PubMed

ABSTRACT

Background: The protection of canola (Brassica napus) crops against blackleg disease, caused by the fungal pathogen Leptosphaeria maculans, is largely mediated by race-specific resistance genes (R-genes). While many R-genes effective against blackleg disease have been identified in Brassica species, information of the precise genomic locations of the genes is limited.

Results: In this study, the Rlm2 gene for resistance to blackleg, located on chromosome A10 of the B. napus cultivar 'Glacier', was targeted for fine mapping. Molecular markers tightly linked to the gene were developed for use in mapping the resistance locus and defining the physical interval in B. napus. Rlm2 was localised to a 5.8 cM interval corresponding to approximately 873 kb of the B. napus chromosome A10.

Conclusion: The recently-cloned B. napus R-gene, LepR3, occupies the same region of A10 as Rlm2 and analysis of the putative B. napus and B. rapa genes in the homologous region identified several additional candidate defense-related genes that may control Rlm2 function.

Show MeSH
Related in: MedlinePlus