Genetic Control and Host Range of Avirulence Toward <i>Brassica napus</i> Cultivars Quinta and Jet Neuf in <i>Leptosphaeria maculans</i>

Mh, Balesdent; Attard, Agnès; Da, Ansan-Melayah; Delourme, Régine; Renard, Michel; Rouxel, Thierry

doi:10.1094/phyto.2001.91.1.70

Cited by 152 publications

(170 citation statements)

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“…There are two types of disease resistance in B. napus: polygenic quantitative resistance (29,30) or specific resistance, which involves major resistance gene(s) (19,39). Nine avirulence genes (AvrLm genes), namely, AvrLm1 to AvrLm9, have been identified in L. maculans (2,(6)(7)(8), and the corresponding nine major resistance genes (Rlm1 to Rlm9) have been described in Brassica sp. (13), as expected in a host-pathogen system with gene-for-gene interactions (17).…”

mentioning

confidence: 99%

Genetic Variability and Distribution of Mating Type Alleles in Field Populations of Leptosphaeria maculans from France

Gout¹,

Eckert

Rouxel³

et al. 2006

Appl Environ Microbiol

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Leptosphaeria maculans is the most ubiquitous fungal pathogen of Brassica crops and causes the devastating stem canker disease of oilseed rape worldwide. We used minisatellite markers to determine the genetic structure of L. maculans in four field populations from France. Isolates were collected at three different spatial scales (leaf, 2-m 2 field plot, and field) enabling the evaluation of spatial distribution of the mating type alleles and of genetic variability within and among field populations. Within each field population, no gametic disequilibrium between the minisatellite loci was detected and the mating type alleles were present at equal frequencies. Both sexual and asexual reproduction occur in the field, but the genetic structure of these populations is consistent with annual cycles of randomly mating sexual reproduction. All L. maculans field populations had a high level of gene diversity (H ‫؍‬ 0.68 to 0.75) and genotypic diversity. Within each field population, the number of genotypes often was very close to the number of isolates. Analysis of molecular variance indicated that >99.5% of the total genetic variability was distributed at a small spatial scale, i.e., within 2-m 2 field plots. Population differentiation among the four field populations was low (G ST < 0.02), suggesting a high degree of gene exchange between these populations. The high gene flow evidenced here in French populations of L. maculans suggests a rapid countrywide diffusion of novel virulence alleles whenever novel resistance sources are used.

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confidence: 99%

Genetic Variability and Distribution of Mating Type Alleles in Field Populations of Leptosphaeria maculans from France

Gout¹,

Eckert

Rouxel³

et al. 2006

Appl Environ Microbiol

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“…by Leptosphaeria maculans, has been shown to involve both qualitative and quantitative resistance (Balesdent et al, 2001;Balesdent et al, 2002). Qualitative resistance is racespecific and depends on the presence of a single resistance (R) gene in the plant corresponding to an avirulence (Avr) gene in the pathogen (Ansan-Melayah et al, 1998).…”

Section: Brassica Resistance Genesmentioning

confidence: 99%

Understanding the structure and variation within the genome of the pathogenic ascomycete fungus Leptosphaeria maculans

Zander¹

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The ascomycete fungus Leptosphaeria maculans is a major pathogen of Brassica species, particularly canola (Brassica napus; rapeseed; oil-seed rape), and the primary cause of crop losses of canola in Australia, causing blackleg disease. L. maculans, a filamentous ascomycete, is the causal agent of phoma stem canker, commonly referred to as blackleg.In late stages of infection, it spreads through the stem vasculature causing lesions, leading to poor growth, lodging and eventually plant death. This fungus is found in canola-growing regions worldwide such as Australia, Canada and Europe. Increased production of canola in these regions has led to a rise in the severity of the disease. In Australia alone, L. maculans infection is responsible for an estimated Australian $100 million in crop losses each year, with average losses ranging from 15-48 % and significant efforts are underway to improve resistance to this disease.Understanding the characteristics of L. maculans is vital for developing an effective and sustainable approach to the management of blackleg disease on Brassica species. The completion of the L. maculans genome sequence was a significant development in the study of this fungal pathogen and provides a reference genome to which molecular markers can be physically mapped. This has been highly useful in other plant pathogens with sequenced genomes, such as the wheat pathogen Parastagonospora nodorum and the cereal pathogen Fusarium graminearum. Importantly, a reference genome also allows mapping of whole genome re-sequencing data, which is becoming a high-throughput, costeffective method to study genome-wide diversity, particularly for the relatively small, lower complexity genomes of many fungal species. By re-sequencing the genome of different L. maculans isolates, variations in genome sequence and structure can be elucidated.Advances in genome sequencing technologies have revolutionised plant and fungal genomics. They have made genome sequencing, re-sequencing and Single Nucleotide Polymorphism (SNP) discovery highly accessible, high-throughput and cost-effective. The process of whole genome re-sequencing involves aligning millions of short sequence reads to a reference genome sequence. Once this has been achieved, it is possible to identify genetic variation between individuals, which can be linked to variation in phenotype to provide molecular genetic markers and insights into gene function.Sequence variation can have a major impact on how an organism develops and responds to the environment. III | P a g eThis thesis describes the implementation of several approaches to elucidating the genome structure and variation of a number of L. maculans isolates, including SNPs and presence/absence variations (PAVs).Initially, the re-sequencing of two L. maculans isolates for the identification of 21,814 SNPs was performed. I demonstrated the application of a novel SNP calling method, SGSautoSNP and its robustness and sensitivity in identifying polymorphisms in L.maculans. I described the use of these S...

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“…This is supported by the absence of Rlm1, Rlm2 or Rlm4 in the diploid C genome species, B. oleracea when screened against L. maculans isolates harbouring AvrLm1, AvrLm2 and AvrLm4 alleles (Rouxel et al, 2003b (Balesdent et al, 2002), Rlm4 in the cultivars Jet Neuf (Balesdent et al, 2001) and Skipton (Raman et al, 2012), Rlm7 in non-commercial lines (Balesdent et al, 2002), and Rlm9 in the cultivar Darmor (Delourme et al, 2004).…”

Section: Genetic Mapping Of Blackleg Resistance Genes In Brassica Spementioning

confidence: 92%

“…ETI triggers a stronger resistance response and often causes localized cell death described as a hypersensitive response (HR) and prevents further infection (Collier andMoffett, 2009, Tsuda andKatagiri, 2010). In the Brassica-L. maculans pathosystem, a typical gene-for-gene interaction has been reported, where the outcome of the infection (resistance or susceptibility) depends on the presence of an R gene in the plant and one corresponding (Avr ) gene in the pathogen (Figure 1.5) (Ansan-Melayah et al, 1998, Balesdent et al, 2001, Balesdent et al, 2002. A set of differential interactions between Brassica species and L. maculans were utilized at the seedling stage using a cotyledon inoculation test (Williams and Delwiche, 1979).…”

Section: Molecular Interaction Between Brassica and L Maculansmentioning

confidence: 99%

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Genome wide identification of NBS-LRR genes in Brassica and their association with disease resistance in Brassica napus

Alamery¹

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Brassica napus (canola/rapeseed/oilseed rape) is an important commercial oilseed crop in Australia with an annual production of approximately 1.6 million tons of oil. Canola is an important source of edible vegetable oil and has a broad range of industrial purposes. Blackleg disease (stem canker) caused by the fungal pathogen Leptosphaeria maculans, is one of the most devastating diseases in B. napus. This disease causes significant yield losses with an annual average loss of 15 to 48 %, although losses can reach up to 80% worldwide, mainly in Europe, Australia and Canada.In order to develop an effective strategy to control the blackleg disease, there is a need to identify blackleg resistance genes in Brassica species and understand the genetic interaction between plant resistance genes and the pathogen avirulence genes. Thus, identification of Nucleotide Binding SiteLeucine Rich Repeat (NBS-LRR) resistance genes is one of the most important objectives of understanding resistance. NBS-LRR resistance genes have been extensively studied because they represent the largest class of disease resistance genes and play a critical role in defending plants from pathogens.The objective of this study was to perform comprehensive analysis on identification and characterization of NBS-LRR genes in the B. napus genome and to study the synteny and conservation of NBS-LRR genes between Brassica species. In this study, a total of 641, 249 and 443 NBS-LRR encoding genes in B. napus, B. rapa and B. oleracea, respectively, were identified.The comparative analysis between B. napus and its progenitor species indicated that NBS-LRR genes exhibited similar gene structure, genomic location, arrangement in clusters and syntenic relationships. The results provide evidence that there was a selective advantage to maintaining similar features of NBS-LRR genes in B. napus to both B. rapa and B. oleracea following polyploidization. More than 60% of NBS LRR genes from the progenitor species were conserved.The differences in NBS-LRR gene conservation could be attributed to gene losses or selection pressure to offer species-specific or cultivars-specific resistance.This study found that the NBS-LRR resistance genes are physically clustered and individual genes involved in clusters were more polymorphic and subject to evolutionary process than singleton genes. These clusters, which have been described in many other species, provide a reservoir of genetic variation influenced by tandem duplication and selection pressure. In addition, there was a significant correlation and co-localization between the number of NBS-LRR genes within the disease QTL intervals and the number of genes involved in gene clusters or duplication. This ii correlation provides evidence that NBS-LRR are distributed and clustered throughout the genome and tends to be linked and associated with disease QTL intervals. Chalhoub, B., Denoeud, F., Liu, S., Parkin, I. A. P., Tang, H., Wang, X., Chiquet, J., Belcram, H., Tong, C., Samans, B., Corréa, M., Da Silva, C., Just, ...

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Genetic Control and Host Range of Avirulence Toward Brassica napus Cultivars Quinta and Jet Neuf in Leptosphaeria maculans

Cited by 152 publications

References 24 publications

Genetic Variability and Distribution of Mating Type Alleles in Field Populations of Leptosphaeria maculans from France

Genetic Variability and Distribution of Mating Type Alleles in Field Populations of Leptosphaeria maculans from France

Understanding the structure and variation within the genome of the pathogenic ascomycete fungus Leptosphaeria maculans

Genome wide identification of NBS-LRR genes in Brassica and their association with disease resistance in Brassica napus

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