Dual control of avirulence in Leptosphaeria maculans towards a Brassica napus cultivar with ‘sylvestris‐derived’ resistance suggests involvement of two resistance genes

Wouw, Angela P. Van de; Marcroft, S. J.; Barbetti, Martin J.; Hua, Li; Salisbury, P. A.; Gout, Lilian; Rouxel, Thierry; Howlett, Barbara J.; Balesdent, Marie‐Hélène

doi:10.1111/j.1365-3059.2008.01982.x

Cited by 79 publications

(83 citation statements)

References 33 publications

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“…Similarly, AvrLm6 was confirmed in 94 isolates, but not in two of the 96 isolates. Since 'Surpass 400' is believed to carry both Rlm1 and LepR3 (Van de Wouw et al, 2008), the presence or absence of AvrLepR3 could be confirmed in only 47 of the 96 isolates.…”

Section: Resultsmentioning

confidence: 99%

Frequency of avirulence genes inLeptosphaeria maculansin western Canada

Kutcher

Balesdent²,

Rimmer

et al. 2010

Canadian Journal of Plant Pathology

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Changes in pathogenicity of populations of Leptosphaeria maculans, the cause of blackleg disease of canola and other Brassica spp., have been observed in western Canada. These changes in the population are believed to have resulted from the use of specific resistance (Rlm) genes in Brassica spp., many of which have only recently been identified. We determined the frequency of 10 avirulence alleles for 96 isolates of L. maculans collected between 1997 and 2005 from Alberta, Saskatchewan and Manitoba, Canada from infested canola stubble in field plots or farmers' fields. Cotyledon interaction phenotypes were scored after inoculation of each isolate on a differential set of Brassica varieties or lines carrying the known resistance genes LepR3 and Rlm1 to Rlm10, except for Rlm8. The avirulence (AvrLm) alleles present in each isolate were inferred from the data. Due to the presence of confounding resistance genes in the host differentials, AvrLm1 and AvrLm2 could not be determined in nine of the isolates, AvrLm6 in two isolates and AvrLepR3 in 49. Based on the number of isolates in which the avirulence genes were confirmed, AvrLm1 was detected in 46.0% and AvrLm9 in 60.4% of the isolates in this collection. A high proportion of isolates carried AvrLm2 (96.6%) and AvrLepR3 (97.9%), and all isolates carried AvrLm6 and AvrLm10. The proportion of L. maculans isolates carrying AvrLm3, AvrLm4, AvrLm5 and AvrLm7 was much lower and varied between 10.4 and 29.2%. In total, 16 races of L. maculans were identified based on 10 avirulence alleles, with seven races accounting for 89.7% of the isolates. Information on the avirulence frequency in the pathogen population will be useful for development of resistance management strategies to control blackleg disease in B. napus oilseed rape in western Canada.Résumé: Des changements dans la pathogénicité des populations de Leptosphaeria maculans, l'agent responsable de la maladie de la Nécrosse du collect chez le canola ainsi que chez d'autres Brassica spp., ont été observés dans l'Ouest canadien. On croit que ces changements résultent de l'utilisation de gènes spécifiques de résistance (Rlm) chez Brassica spp., dont plusieurs n'ont été que récemment identifiés. Nous avons déterminé la fréquence de 10 allèles d'avirulence pour 96 isolats de L. maculans collectés, de 1997 à 2005, en Alberta, en Saskatchewan et au Manitoba, sur du chaume de canola infecté provenant de parcelles expérimentales et de champs cultivés. Les phénotypes d'interaction ont été notés sur cotyiédons après inoculation de chaque isolat sur un groupe différentiel de variétés de Brassica ou de lignées portant les gènes de résistance connus LepR3 et Rlm1 à Rlm10, sauf Rlm8. Les allèles d'avirulence (AvrLm) présents dans chaque isolat ont été déduits des données. Étant donnée la présence simultanèe de gènes de résistance dans certains hôtes différentiels, AvrLm1 et AveLm2 n'ont pu être confirmés dans neuf des isolats, AvrLm6, dans deux et AvrLepR3, dans 49. En se basant sur le nombre d'isolats dans lesquels la présence de...

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Section: Resultsmentioning

confidence: 99%

Frequency of avirulence genes inLeptosphaeria maculansin western Canada

Kutcher

Balesdent²,

Rimmer

et al. 2010

Canadian Journal of Plant Pathology

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“…Twelve of these R genes have been positioned in the A genome of B. napus or B. rapa ( Rlm1, Rlm2, Rlm3, Rlm4, Rlm7, Rlm9, LepR1, LepR2, LepR3, LepR4 ) or the B genome of B. juncea ( LmJR1, LmJR2 ) via linkage mapping (Delourme et al, 2004; Yu et al, 2005, 2007, 2012; Christianson et al, 2006; Long et al, 2011; Raman et al, 2012a,b; Larkan et al, 2013, 2014, 2016), while two more have been assigned to B genome chromosomes of B. juncea and/or B. nigra ( Rlm6, Rlm10 ) through marker-based assessment of recombinant or chromosome addition lines (Chèvre et al, 1996, 1997; Eber et al, 2011). RlmS , identified in the B. napus variety Surpass 400 (Van De Wouw et al, 2009) likely corresponds to the BlmR2 locus mapped to chromosome A10 (Long et al, 2011; Larkan et al, 2013). The remaining R genes ( Rlm5, Rlm8, Rlm11 , and RlmJ1 ) have yet to be genetically characterized in the host Brassica lines in which they reside.…”

Section: Introductionmentioning

confidence: 99%

Single R Gene Introgression Lines for Accurate Dissection of the Brassica - Leptosphaeria Pathosystem

Larkan

Lydiate

et al. 2016

Front. Plant Sci.

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Seven blackleg resistance (R) genes (Rlm1, Rlm2, Rlm3, Rlm4, LepR1, LepR2 & LepR3) were each introgressed into a common susceptible B. napus doubled-haploid (DH) line through reciprocal back-crossing, producing single-R gene introgression lines (ILs) for use in the pathological and molecular study of Brassica—Leptosphaeria interactions. The genomic positions of the R genes were defined through molecular mapping and analysis with transgenic L. maculans isolates was used to confirm the identity of the introgressed genes where possible. Using L. maculans isolates of contrasting avirulence gene (Avr) profiles, we preformed extensive differential pathology for phenotypic comparison of the ILs to other B. napus varieties, demonstrating the ILs can provide for the accurate assessment of Avr-R gene interactions by avoiding non-Avr dependant alterations to resistance responses which can occur in some commonly used B. napus varieties. Whole-genome SNP-based assessment allowed us to define the donor parent introgressions in each IL and provide a strong basis for comparative molecular dissection of the pathosystem.

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“…At least eleven R genes conferring resistance to L. maculans have been identified in Brassicas (Delourme et al 2006;Yu et al 2008;Van de Wouw et al 2009). At least nine corresponding L. maculans Avr genes have been genetically characterised (AvrLm1-AvrLm9) and AvrLm1, AvrLm4, AvrLm6 and AvrLm7 have now been cloned (Gout et al 2006;Fudal et al 2007;Parlange et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Fitness cost of virulence differs between the AvrLm1 and AvrLm4 loci in Leptosphaeria maculans (phoma stem canker of oilseed rape)

Huang

Balesdent

et al. 2009

Eur J Plant Pathol

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???The original publication is available at www.springerlink.com??? Copyright Springer [Full text of this article is not available in the UHRA]To investigate whether the reported fitness cost of virulence at the AvrLm4 locus in Leptosphaeria maculans is common to other loci, near-isogenic (NI) isolates differing at AvrLm1 locus were produced in vitro. Fitness of virulent (avrLm1) or avirulent (AvrLm1) isolates on Brassica napus without the corresponding R (resistance) gene Rlm1 was investigated in controlled environment (CE) and field experiments. Results indicate that there is a measurable fitness cost for avrLm1 compared to AvrLm1 isolates in terms of number of lesions, size of lesions, distance grown through leaf tissue towards the petiole in CE experiments and systemic growth from leaf lesions to stems in field experiments. There were differences in fitness cost between the AvrLm1 and AvrLm4 loci. There was a cultivar effect on fitness cost of virulence at the AvrLm1 locus but not at the AvrLm4 locus. In CE experiments, the optimal temperature for leaf infection was greater for AvrLm4 isolates than for AvrLm1 isolates. Field experiment results suggest that on the same host AvrLm4 isolates are more fit than AvrLm1 isolates in warmer seasons. The fitness cost at the AvrLm4 locus was generally greater than at the AvrLm1 locus, suggesting that the corresponding R gene Rlm4 may be more suitable than Rlm1 for redeployment in commercial cultivars after an interval of a few years

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Dual control of avirulence in Leptosphaeria maculans towards a Brassica napus cultivar with ‘sylvestris‐derived’ resistance suggests involvement of two resistance genes

Cited by 79 publications

References 33 publications

Frequency of avirulence genes inLeptosphaeria maculansin western Canada

Frequency of avirulence genes inLeptosphaeria maculansin western Canada

Single R Gene Introgression Lines for Accurate Dissection of the Brassica - Leptosphaeria Pathosystem

Fitness cost of virulence differs between the AvrLm1 and AvrLm4 loci in Leptosphaeria maculans (phoma stem canker of oilseed rape)

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