Association mapping of quantitative resistance for Leptosphaeria maculans in oilseed rape (Brassica napus L.)

Abstract Key message Quantitative resistance (QR) loci discovered through genetic and genomic analyses are abundant in the Brassica napus genome, providing an opportunity for their utilization in enhancing blackleg resistance. Abstract Quantitative resistance (QR) has long been utilized to manage blackleg in Brassica napus (canola, oilseed rape), even before major resistance genes (R-genes) were extensively explored in breeding programmes. In contrast to R-gene-mediated qualitative resistance, QR reduces blackleg symptoms rather than completely eliminating the disease. As a polygenic trait, QR is controlled by numerous genes with modest effects, which exerts less pressure on the pathogen to evolve; hence, its effectiveness is more durable compared to R-gene-mediated resistance. Furthermore, combining QR with major R-genes has been shown to enhance resistance against diseases in important crops, including oilseed rape. For these reasons, there has been a renewed interest among breeders in utilizing QR in crop improvement. However, the mechanisms governing QR are largely unknown, limiting its deployment. Advances in genomics are facilitating the dissection of the genetic and molecular underpinnings of QR, resulting in the discovery of several loci and genes that can be potentially deployed to enhance blackleg resistance. Here, we summarize the efforts undertaken to identify blackleg QR loci in oilseed rape using linkage and association analysis. We update the knowledge on the possible mechanisms governing QR and the advances in searching for the underlying genes. Lastly, we lay out strategies to accelerate the genetic improvement of blackleg QR in oilseed rape using improved phenotyping approaches and genomic prediction tools.

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Seed Yield and Sulphur Partitioning in Two Inbred Lines of Low and High Glucosinolate Oilseed Rape (Brassica napus L.) and Their Hybrids at Three Levels of Sulphur Supply

Acta Agriculturae Scandinavica Section B - Soil & Plant Science ◽

10.1080/09064719908565565 ◽

1999 ◽

Vol 49 (3) ◽

pp. 184-188

Author(s):

J. Davik ◽

A. K. Bakken

Keyword(s):

Brassica Napus ◽

Oilseed Rape ◽

Seed Yield ◽

Inbred Lines ◽

Brassica Napus L

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Genome Mining and Evaluation of the Biocontrol Potential of Pseudomonas fluorescens BRZ63, a New Endophyte of Oilseed Rape (Brassica napus L.) against Fungal Pathogens

International Journal of Molecular Sciences ◽

10.3390/ijms21228740 ◽

2020 ◽

Vol 21 (22) ◽

pp. 8740

Author(s):

Daria Chlebek ◽

Artur Pinski ◽

Joanna Żur ◽

Justyna Michalska ◽

Katarzyna Hupert-Kocurek

Keyword(s):

Brassica Napus ◽

Plant Growth ◽

Pseudomonas Fluorescens ◽

Oilseed Rape ◽

Plant Growth Promotion ◽

Fungal Pathogens ◽

Growth Promotion ◽

Genome Mining ◽

Plant Colonization ◽

Brassica Napus L

Endophytic bacteria hold tremendous potential for use as biocontrol agents. Our study aimed to investigate the biocontrol activity of Pseudomonas fluorescens BRZ63, a new endophyte of oilseed rape (Brassica napus L.) against Rhizoctonia solani W70, Colletotrichum dematium K, Sclerotinia sclerotiorum K2291, and Fusarium avenaceum. In addition, features crucial for biocontrol, plant growth promotion, and colonization were assessed and linked with the genome sequences. The in vitro tests showed that BRZ63 significantly inhibited the mycelium growth of all tested pathogens and stimulated germination and growth of oilseed rape seedlings treated with fungal pathogens. The BRZ63 strain can benefit plants by producing biosurfactants, siderophores, indole-3-acetic acid (IAA), 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and ammonia as well as phosphate solubilization. The abilities of exopolysaccharide production, autoaggregation, and biofilm formation additionally underline its potential to plant colonization and hence biocontrol. The effective colonization properties of the BRZ63 strain were confirmed by microscopy observations of EGFP-expressing cells colonizing the root surface and epidermal cells of Arabidopsis thaliana Col-0. Genome mining identified many genes related to the biocontrol process, such as transporters, siderophores, and other secondary metabolites. All analyses revealed that the BRZ63 strain is an excellent endophytic candidate for biocontrol of various plant pathogens and plant growth promotion.

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

International Journal of Molecular Sciences ◽

10.3390/ijms22010313 ◽

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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