scholarly journals Brassica napus genes Rlm4 and Rlm7, conferring resistance to Leptosphaeria maculans, are alleles of the Rlm9 wall-associated kinase-like resistance locus

2021 ◽  
Author(s):  
Parham Haddadi ◽  
Nicholas J Larkan ◽  
Angela Van de Wouw ◽  
Yueqi Zhang ◽  
Ting Xiang Neik ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Genome Sequence ◽  
Leptosphaeria Maculans ◽  
Resistance Locus ◽  
R Genes ◽  
Blackleg Disease ◽  
Wild Type ◽  
Resistance Response ◽  
Induce Resistance ◽  
Gene Structures

Brassica napus (canola/rapeseed) race specific resistance genes against blackleg disease, caused by the ascomycete fungus Leptosphaeria maculans, have been commonly used in canola breeding. To date, LepR3, Rlm2 and Rlm9 R genes against L. maculans have been cloned from B. napus. LepR3 and Rlm2 are Receptor Like Proteins (RLP) and the recently reported Rlm9 is a Wall Associated Kinase-Like (WAKL) protein. Rlm9 located on chromosome A07 is closely linked with Rlm3, Rlm4, RLm7 genes. Recognition of AvrLm5-9 and AvrLm3 by their corresponding Rlm9 and Rlm3 proteins is masked in the presence of AvrLm4-7. Here we report cloning of Rlm4 and Rlm7 by generating genome sequence of the doubled haploid (DH) B. napus cv Topas DH16516 introgression lines Topas-Rlm4 and Topas-Rlm7. Candidate Rlm4 and Rlm7 genes were identified form the genome sequence and gene structures were determined by mapping RNA-sequence reads, generated from infected cotyledon tissues, to the genome of Topas-Rlm4 and Topas-Rlm7. Rlm4 and Rlm7 genomic constructs with their native promoters were transferred into the blackleg susceptible B. napus cv Westar. Complementation of resistance response in the transgenic Westar-Rlm4 and Westar-Rlm7 that were inoculated with L. maculans transgenic isolates 2367-AvrRlm4-7 or 2367-AvrLm7 confirmed the function of Rlm4 and Rlm7 genes. Wild type L. maculans isolate 2367 that does not contain AvrLm4-7 or AvrLm7, and transgenic 2367-AvrLm3 and 2367-AvrLm5-9 did not induce resistance proving the specificity of Rlm4 and Rlm7 response. Rlm4 and Rlm7 alleles are also allelic to Rlm9. Rlm4 and Rlm7 genes encode WAKL proteins. Comparison of highly-homologous sequences of Rlm4 and Rlm7 with each other and with the sequence of additional alleles identified a limited number of point mutation located within the predicted extracellular receptor domains.

scholarly journals Insights into fighting against blackleg disease of Brassica napus in Canada

2018 ◽  
Vol 69 (1) ◽  
pp. 40 ◽  
Author(s):  
Xuehua Zhang ◽  
W. G. Dilantha Fernando
Keyword(s):  
Brassica Napus ◽  
Disease Control ◽  
Resistance Genes ◽  
Leptosphaeria Maculans ◽  
Western Canada ◽  
R Genes ◽  
Blackleg Disease ◽  
Evolutionary Potential ◽  
Fungal Populations ◽  
Major Resistance Genes

Blackleg disease, caused by the ascomycete fungal pathogen Leptosphaeria maculans, is a devastating disease of canola (Brassica napus) in Australia, Canada and Europe. Although cultural strategies such as crop rotation, fungicide application, and tillage are adopted to control the disease, the most promising disease control strategy is the utilisation of resistant canola varieties. However, field populations of L. maculans display a high evolutionary potential and are able to overcome major resistance genes within a few years, making disease control relying on resistant varieties challenging. In the early 1990s, blackleg resistance gene Rlm3 was introduced into Canadian canola varieties and provided good resistance against the fungal populations until the early 2000s, when moderate to severe blackleg outbreaks were observed in some areas across western Canada. However, the breakdown of Rlm3 resistance was not reported until recently, based on studies on R genes present in Canadian canola varieties and the avirulence allele frequency in L. maculans populations in western Canada. The fact that Rlm3 was overcome by the evolution of fungal populations demands canola breeding programs in Canada to be prepared to develop canola varieties with diversified and efficient R genes. In addition, frequent monitoring of fungal populations can provide up-to-date guidance for proper resistance genes deployment. This literature review provides insights into the outbreaks and management of blackleg disease in Canada.

scholarly journals Effect of Leptosphaeria maculans Infection on Promoter DNA Methylation of Defence Genes in Brassica napus

Agronomy ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1072 ◽  
Author(s):  
Soodeh Tirnaz ◽  
Clementine Merce ◽  
Philipp E. Bayer ◽  
Anita A. Severn-Ellis ◽  
David Edwards ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Brassica Napus ◽  
Leptosphaeria Maculans ◽  
Methylation Pattern ◽  
Epigenetic Mark ◽  
Gene Promoters ◽  
Blackleg Disease ◽  
Crop Species ◽  
Resistance Response ◽  
Defence Genes

Canola (Brassica napus) is an important crop species grown worldwide for its seeds, which are crushed for edible oil. Canola production is threatened by blackleg disease, caused by the fungal pathogen Leptosphaeria maculans, which can lead up to 100% yield loss. A plant’s disease resistance response depends highly on the regulation of the expression of defence genes. DNA methylation, an epigenetic mark, is one of the most important regulatory mechanisms in a plant’s defence system. Here, the DNA methylation pattern of promoters of defence genes has been investigated between leaves from control and infected plants with L. maculans of resistant and susceptible cultivars of B. napus. In total, over 12,000 promoters were found to be differentially methylated between leaves from control and infected plants in the two cultivars, of which 225 promoters were related to defence genes and differentially methylated between the resistant and susceptible cultivars. The majority of defence gene promoters were hypo- or hyper-methylated in the first and second true leaves, but not in the third and fourth leaves. The outcomes will assist in developing an insight into genome-wide DNA methylation patterns in canola cultivars, and ultimately help breeders to optimise the breeding programmes for enhancing resistance against blackleg disease.

scholarly journals Genetic Analysis of a Horizontal Resistance Locus BLMR2 in Brassica napus

2021 ◽  
Vol 12 ◽  
Author(s):  
Qiang Zhang ◽  
Hanna Dandena ◽  
Madison McCausland ◽  
Huizhi Liu ◽  
Zheng Liu ◽  
...  
Keyword(s):  
Molecular Markers ◽  
Brassica Napus ◽  
Chromosome Region ◽  
Leptosphaeria Maculans ◽  
Snp Markers ◽  
Resistance Locus ◽  
Horizontal Resistance ◽  
Blackleg Disease ◽  
Single Nucleotide ◽  
Sequence Characterized Amplified Regions

Leptosphaeria maculans causes blackleg disease in Brassica napus. The blackleg disease is mainly controlled by resistance genes in B. napus. Previous studies have shown that the blackleg resistant BLMR2 locus that conferred horizontal resistance under field conditions, is located on chromosome A10 of B. napus. The purpose of this study is to fine map this locus and hence identify a candidate gene underlying horizontal resistance. The spectrum of resistance to L. maculans isolates of the resistance locus BLMR2 was analyzed using near isogenic lines, resistant, and susceptible cultivars. The results showed that this locus was horizontally resistant to all isolates tested. Sequence characterized amplified regions (SCAR), simple sequence repeats (SSR), and single nucleotide polymorphism (SNP) markers were developed in the chromosome region of BLMR2 and a fine genetic map was constructed. Two molecular markers narrowed BLMR2 in a 53.37 kb region where six genes were annotated. Among the six annotated genes, BnaA10g11280D/BnaA10g11290D encoding a cytochrome P450 protein were predicted as the candidate of BLMR2. Based on the profiling of pathogen induced transcriptome, three expressed genes in the six annotated genes were identified while only cytochrome P450 showed upregulation. The candidate corresponds to the gene involved in the indole glucosinolate biosynthesis pathway and plant basal defense in Arabidopsis thaliana. The molecular markers identified in this study will allow the quick incorporation of the BLMR2 allele in rapeseed cultivars to enhance blackleg resistance.

scholarly journals Recent Findings Unravel Genes and Genetic Factors Underlying Leptosphaeria maculans Resistance in Brassica napus and Its Relatives

2020 ◽  
Vol 22 (1) ◽  
pp. 313
Author(s):  
Aldrin Y. Cantila ◽  
Nur Shuhadah Mohd Saad ◽  
Junrey C. Amas ◽  
David Edwards ◽  
Jacqueline Batley
Keyword(s):  
Brassica Napus ◽  
Genetic Factors ◽  
Quantitative Resistance ◽  
Genetic Resistance ◽  
Leptosphaeria Maculans ◽  
Gene Interaction ◽  
R Gene ◽  
R Genes ◽  
Blackleg Resistance ◽  
Avr Gene

Among the Brassica oilseeds, canola (Brassica napus) is the most economically significant globally. However, its production can be limited by blackleg disease, caused by the fungal pathogen Lepstosphaeria maculans. The deployment of resistance genes has been implemented as one of the key strategies to manage the disease. Genetic resistance against blackleg comes in two forms: qualitative resistance, controlled by a single, major resistance gene (R gene), and quantitative resistance (QR), controlled by numerous, small effect loci. R-gene-mediated blackleg resistance has been extensively studied, wherein several genomic regions harbouring R genes against L. maculans have been identified and three of these genes were cloned. These studies advance our understanding of the mechanism of R gene and pathogen avirulence (Avr) gene interaction. Notably, these studies revealed a more complex interaction than originally thought. Advances in genomics help unravel these complexities, providing insights into the genes and genetic factors towards improving blackleg resistance. Here, we aim to discuss the existing R-gene-mediated resistance, make a summary of candidate R genes against the disease, and emphasise the role of players involved in the pathogenicity and resistance. The comprehensive result will allow breeders to improve resistance to L. maculans, thereby increasing yield.

scholarly journals Limitations of transcriptome-based prediction of pathogenicity genes in the plant pathogen Leptosphaeria maculans

2019 ◽  
Vol 366 (7) ◽  
Author(s):  
Andrew S Urquhart ◽  
Alexander Idnurm
Keyword(s):  
Gene Expression ◽  
Brassica Napus ◽  
Leptosphaeria Maculans ◽  
Simple Expression ◽  
Gene Transcript ◽  
Blackleg Disease ◽  
Fungal Pathogenicity ◽  
Transcript Levels ◽  
Oilseed Crops ◽  
High Gene

ABSTRACT Identification of pathogenicity determinants in Leptosphaeria maculans, a major cause of disease of oilseed crops, has been a focus of research for many years. A wealth of gene expression information from RNA sequencing promises to illuminate the mechanisms by which the fungus is able to cause blackleg disease. However, to date, no studies have tested the hypothesis that high gene transcript levels during infection correlate with importance to disease progression. In this study, we use CRISPR-Cas9 to disrupt 11 genes that are highly expressed during the early stages of disease and show that none of these genes are crucial for fungal pathogenicity on Brassica napus. This finding suggests that in order to understand the pathogenicity of this fungus more sophisticated techniques than simple expression analysis will need to be employed.

scholarly journals Genome-Wide Identification and Analysis of VQ Motif-containing Gene Family in Brassica napus and Functional Characterization of BnMKS1 in Response to Leptosphaeria maculans

2020 ◽  
Author(s):  
Zhongwei Zou ◽  
Fei Liu ◽  
Shuanglong Huang ◽  
DILANTHA GERARD FERNANDO
Keyword(s):  
Brassica Napus ◽  
Gene Family ◽  
Functional Characterization ◽  
Leptosphaeria Maculans ◽  
Defense Responses ◽  
Marker Genes ◽  
Blackleg Disease ◽  
Genome Wide ◽  
A Genome

Proteins containing Valine-glutamine (VQ) motifs play important roles in plant growth and development, as well as in defense responses to both abiotic and biotic stresses. Blackleg disease, which is caused by Leptosphaeria maculans, is the most important disease in canola (Brassica napus L.) worldwide. H; however, the identification of B. napus VQs and their functions in response to blackleg disease have not yet been reported. In this study, we conducted a genome genome-wide identification and characterization of the VQ gene family in B. napus, including chromosome location, phylogenetic relations, gene structure, motif domain, synteny analysis, and cis-elements categorization of their promoter regions. To understand B. napus VQ gene function in response to blackleg disease, we overexpressed BnVQ7 (BnaA01g36880D, also known as the mitogen-activated protein kinase4 substrate1 (MKS1) gene) in a blackleg-susceptible canola variety Westar. Overexpression The overexpression of BnMKS1 in canola did not improve its resistance to blackleg disease at the seedling stage. H; however, transgenic canola plants overexpressing BnMKS1 displayed an enhanced resistance to L. maculans infection at the adult plant stage. Expression levels of downstream and defense marker genes in cotyledons increased significantly at the necrotrophic stage of L. maculans infection in the overexpression line of BnMKS1, suggesting that the SA salicylic acid (SA)- and jasmonic acid (JA )-mediated signaling pathways were both involved in the defense responses. Together, these results suggest that BnMKS1 might play an important role in the defense against L. maculans.

scholarly journals Isocitrate Lyase Is Essential for Pathogenicity of the Fungus Leptosphaeria maculans to Canola (Brassica napus)

2002 ◽  
Vol 1 (5) ◽  
pp. 719-724 ◽  
Author(s):  
Alexander Idnurm ◽  
Barbara J. Howlett
Keyword(s):  
Brassica Napus ◽  
Reverse Genetics ◽  
Isocitrate Lyase ◽  
Glyoxylate Cycle ◽  
Pathogenic Fungus ◽  
Leptosphaeria Maculans ◽  
Bacterial Pathogen ◽  
Hygromycin Resistance ◽  
Wild Type ◽  
Glyoxylate Pathway

ABSTRACT A pathogenicity gene has been identified in Leptosphaeria maculans, the ascomycetous fungus that causes blackleg disease of canola (Brassica napus). This gene encodes isocitrate lyase, a component of the glyoxylate cycle, and is essential for the successful colonization of B. napus. It was identified by a reverse genetics approach whereby a plasmid conferring hygromycin resistance was inserted randomly into the L. maculans genome. Twelve of 516 transformants tested had reduced pathogenicity on cotyledons of B. juncea and B. napus, and 1 of these 12 had a deletion of the isocitrate lyase gene, as well as an insertion of the hygromycin resistance gene. This mutant was unable to grow on fatty acids, including monolaurate, and the isocitrate lyase transcript was not detected. When the wild-type gene was reintroduced into the mutant, growth on monolaurate was restored and pathogenicity was partially restored. L. maculans isocitrate lyase is produced during infection of B. napus cotyledons, while the plant homologue is not. When 2.5% glucose was added to the inoculum of the isocitrate lyase mutant, lesions of sizes similar to those caused by wild-type isolate M1 developed on B. napus cotyledons. These findings suggest that the glyoxylate pathway is essential for disease development by this plant-pathogenic fungus, as has been shown recently for a fungal and bacterial pathogen of animals and a bacterial pathogen of plants. Involvement of the glyoxylate pathway in pathogenesis in animals and plants presents potential drug targets for control of diseases.

Identification and mapping of a third blackleg resistance locus in Brassica napus derived from B. rapa subsp. sylvestris

Genome ◽  
2008 ◽  
Vol 51 (1) ◽  
pp. 64-72 ◽  
Author(s):  
Fengqun Yu ◽  
Derek J. Lydiate ◽  
S. Roger Rimmer
Keyword(s):  
Brassica Napus ◽  
Linkage Group ◽  
Resistance Gene ◽  
Leptosphaeria Maculans ◽  
Resistance Locus ◽  
Dominant Allele ◽  
Breeding Lines ◽  
Disease Reaction ◽  
Blackleg Resistance ◽  
Map Location

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 F1 and BC1 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.

Sign in / Sign up

Export Citation Format

Share Document