scholarly journals Transcriptional Insight Into Brassica napus Resistance Genes LepR3 and Rlm2-Mediated Defense Response Against the Leptosphaeria maculans Infection

2019 ◽  
Vol 10 ◽  
Author(s):  
Tengsheng Zhou ◽  
Wen Xu ◽  
Arvind H. Hirani ◽  
Zheng Liu ◽  
Pham Anh Tuan ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Resistance Genes ◽  
Defense Response ◽  
Leptosphaeria Maculans ◽  
Insight Into

scholarly journals Tissue-specific mRNA profiling of the Brassica napus-Sclerotinia sclerotiorum interaction uncovers novel regulators of plant immunity

2021 ◽  
Author(s):  
Philip Walker ◽  
Ian Girard ◽  
Shayna Giesbrecht ◽  
Steve Whyard ◽  
Dilantha Fernando ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Sclerotinia Sclerotiorum ◽  
Defense Response ◽  
Plant Immunity ◽  
Leaf Tissue ◽  
Specific Gene ◽  
Tissue Specific ◽  
Biotrophic Pathogens ◽  
Dna Insertion ◽  
Insight Into

White mold in Brassica napus (canola) is caused by the fungal pathogen Sclerotinia sclerotiorum and is responsible for significant losses in crop yield across the globe. With advances in high-throughput transcriptomics, our understanding of the B. napus defense response to S. sclerotiorum is becoming clearer; however, the response of individual tissue layers directly at the site of infection has yet to be explored. Using laser microdissection coupled with RNA sequencing, we profiled the epidermis, mesophyll and vascular leaf tissue layers in response to S. sclerotiorum. This strategy increases the number of genes detected compared to whole-leaf assessments and provides unprecedented information on tissue-specific gene expression networks in response to pathogen attack. Our findings provide novel insight into the conserved and specific roles of ontogenetically distinct leaf tissue layers in response to infection. Using bioinformatics tools, we identified several defense genes that might coordinate plant immunity responses shared across different tissue layers within the leaf. These genes were functionally characterized by challenging T-DNA insertion lines of Arabidopsis with necrotrophic, hemi-biotrophic, and biotrophic pathogens, ultimately converging on the PR5-like RECEPTOR KINASE (PRK5). Together, these data provide insight on the complexity of the B. napus defense response directly at the site of infection.

Identifying resistance genes to Leptosphaeria maculans in Australian Brassica napus cultivars based on reactions to isolates with known avirulence genotypes

2012 ◽  
Vol 63 (4) ◽  
pp. 338 ◽  
Author(s):  
Steve J. Marcroft ◽  
Vicki L. Elliott ◽  
Anton J. Cozijnsen ◽  
Phillip A. Salisbury ◽  
Barbara J. Howlett ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Resistance Genes ◽  
Adult Plant Resistance ◽  
Leptosphaeria Maculans ◽  
Mortality Data ◽  
Adult Plant ◽  
Blackleg Disease ◽  
Seedling Resistance ◽  
Breeding Lines ◽  
Fungal Populations

Blackleg disease, caused by the fungus Leptosphaeria maculans, is the major disease of canola (Brassica napus) worldwide. A set of 12 Australian L. maculans isolates was developed and used to characterise seedling resistance in 127 Australian cultivars and advanced breeding lines. Plant mortality data used to assess the effectiveness of seedling resistance in canola growing regions of Australia showed that Rlm3 and Rlm4 resistance genes were less effective than other seedling resistance genes. This finding was consistent with regional surveys of the pathogen, which showed the frequency of Rlm4-attacking isolates was >70% in fungal populations over a 10-year period. Differences in adult plant resistance were identified in a subset of Australian cultivars, indicating that some adult gene resistance is isolate-specific.

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 A Cluster of Major Specific Resistance Genes to Leptosphaeria maculans in Brassica napus

2004 ◽  
Vol 94 (6) ◽  
pp. 578-583 ◽  
Author(s):  
R. Delourme ◽  
M. L. Pilet-Nayel ◽  
M. Archipiano ◽  
R. Horvais ◽  
X. Tanguy ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Resistance Genes ◽  
Specific Resistance ◽  
Quantitative Resistance ◽  
Specific Interaction ◽  
Leptosphaeria Maculans ◽  
Field Resistance ◽  
Genetic Identification ◽  
Adult Plant ◽  
Avirulence Genes

Two types of genetic resistance to Leptosphaeria maculans usually are distinguished in Brassica napus: qualitative, total resistance expressed at the seedling stage and quantitative, partial resistance expressed at the adult plant stage. The latter is under the control of many genetic factors that have been mapped through quantitative trait loci (QTL) studies using ‘Darmor’ resistance. The former usually is ascribed to race-specific resistance controlled by single resistance to L. maculans (Rlm) genes. Three B. napus-originating specific Rlm genes (Rlm1, Rlm2, and Rlm4) previously were characterized. Here, we report on the genetic identification of two novel resistance genes, Rlm3 and Rlm7, corresponding to the avirulence genes AvrLm3 and AvrLm7. The identification of a novel L. maculans- B. napus specific interaction allowed the detection of another putative new specific resistance gene, Rlm9. The resistance genes were mapped in two genomic regions on LG10 and LG16 linkage groups. A cluster of five resistance genes (Rlm1, Rlm3, Rlm4, Rlm7, and Rlm9) was strongly suggested on LG10. The relation between all these specific resistance genes and their potential role in adult-plant field resistance is discussed. These two Rlm-carrying regions do not correspond to major QTL for Darmor quantitative resistance.

scholarly journals A Field Method for Evaluating the Potential Durability of New Resistance Sources: Application to the Leptosphaeria maculans-Brassica napus Pathosystem

2000 ◽  
Vol 90 (9) ◽  
pp. 961-966 ◽  
Author(s):  
H. Brun ◽  
S. Levivier ◽  
I. Somda ◽  
D. Ruer ◽  
M. Renard ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Field Experiment ◽  
Resistance Genes ◽  
Leptosphaeria Maculans ◽  
Rapid Change ◽  
Natural Populations ◽  
Field Method ◽  
Addition Line ◽  
Resistant Lines ◽  
High Level

To increase the longevity of new resistance genes by avoiding a rapid change in pathogen populations, we established a new field method to determine, before the release of a resistant cultivar, whether and how rapidly the pathogen population is capable of responding to the selective pressure we impose. This method was applied to the Leptosphaeria maculans-Brassica napus pathosystem. The potential durability of two new major resistance genes introgressed into B. napus from the Brassica B genome was tested separately for each gene under field conditions for 4 years. Successive inoculations with residues of the resistant lines mixed with susceptible contaminated plant material recovered at harvest the previous year were performed in autumn. The Jlm1 resistance gene originating from B. juncea conferred complete resistance on the B. napus-B. juncea recombinant lines MX and MXS to inoculation of the cotyledons with a large diversity of L. maculans isolates. It also gave a high level of stem canker resistance in the field against natural populations of the pathogen. A similar level of resistance was obtained in the B. napus-B. nigra addition line LA4+, containing B. nigra chromosome 4 in a B. napus background. In the second year of the field experiment (i.e., the first in which residues from the resistant lines were included in the inoculation material), both MX and LA4+ maintained a high level of resistance. In the third and fourth years of the field experiment, the resistance of MX and MXS exposed to inoculum produced from their own residues broke down, but against fungal populations from susceptible B. napus or resistant B. nigra material remained effective. In contrast, LA4+ remained highly resistant to all sources of inoculum for the 4-year experiment.

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.

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