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Redkar A, Cevik V, Bailey K, Zhao H, Kim DS, Zou Z, Furzer OJ, Fairhead S, Borhan MH, Holub EB, Jones JDG. The Arabidopsis WRR4A and WRR4B paralogous NLR proteins both confer recognition of multiple Albugo candida effectors. New Phytol 2023; 237:532-547. [PMID: 35838065 PMCID: PMC10087428 DOI: 10.1111/nph.18378] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 07/05/2022] [Indexed: 05/26/2023]
Abstract
The oomycete Albugo candida causes white blister rust, an important disease of Brassica crops. Distinct races of A. candida are defined by their capacity to infect different host plant species. Each A. candida race encodes secreted proteins with a CX2 CX5 G ('CCG') motif that are polymorphic and show presence/absence variation, and are therefore candidate effectors. The White Rust Resistance 4 (WRR4) locus in Arabidopsis thaliana accession Col-0 contains three genes that encode intracellular nucleotide-binding domain leucine-rich repeat immune receptors. The Col-0 alleles of WRR4A and WRR4B confer resistance to multiple A. candida races, although both WRR4A and WRR4B can be overcome by the Col-0-virulent race 4 isolate AcEx1. Comparison of CCG candidate effectors in avirulent and virulent races, and transient co-expression of CCG effectors from four A. candida races in Nicotiana sp. or A. thaliana, revealed CCG effectors that trigger WRR4A- or WRR4B-dependent hypersensitive responses. We found eight WRR4A-recognised CCGs and four WRR4B-recognised CCGs, the first recognised proteins from A. candida for which the cognate immune receptors in A. thaliana are known. This multiple recognition capacity potentially explains the broad-spectrum resistance to several A. candida races conferred by WRR4 paralogues. We further show that of five tested CCGs, three confer enhanced disease susceptibility when expressed in planta, consistent with A. candida CCG proteins being effectors.
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Affiliation(s)
- Amey Redkar
- The Sainsbury LaboratoryUniversity of East AngliaNorwichNR4 7UHUK
- Department of BotanySavitribai Phule Pune UniversityGaneshkhindPune411007India
| | - Volkan Cevik
- The Sainsbury LaboratoryUniversity of East AngliaNorwichNR4 7UHUK
- The Milner Centre for Evolution, Department of Biology and BiochemistryUniversity of BathBathBA2 7AYUK
| | - Kate Bailey
- The Sainsbury LaboratoryUniversity of East AngliaNorwichNR4 7UHUK
| | - He Zhao
- The Sainsbury LaboratoryUniversity of East AngliaNorwichNR4 7UHUK
| | - Dae Sung Kim
- The Sainsbury LaboratoryUniversity of East AngliaNorwichNR4 7UHUK
- Present address:
State Key Laboratory of Biocatalysis and Enzyme EngineeringHubei UniversityWuhan430062China
| | - Zhou Zou
- The Milner Centre for Evolution, Department of Biology and BiochemistryUniversity of BathBathBA2 7AYUK
| | - Oliver J. Furzer
- The Sainsbury LaboratoryUniversity of East AngliaNorwichNR4 7UHUK
- Department of BiologyUniversity of North CarolinaChapel HillNC27599USA
| | - Sebastian Fairhead
- The Sainsbury LaboratoryUniversity of East AngliaNorwichNR4 7UHUK
- School of Life SciencesWarwick Crop Centre, University of WarwickWellesbourneCV35 9EFUK
| | - M. Hossein Borhan
- Agriculture and Agri‐Food Canada107 Science PlaceSaskatoonSKS7N 0X2Canada
| | - Eric B. Holub
- School of Life SciencesWarwick Crop Centre, University of WarwickWellesbourneCV35 9EFUK
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Borhan MH, Van de Wouw AP, Larkan NJ. Molecular Interactions Between Leptosphaeria maculans and Brassica Species. Annu Rev Phytopathol 2022; 60:237-257. [PMID: 35576591 DOI: 10.1146/annurev-phyto-021621-120602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Canola is an important oilseed crop, providing food, feed, and fuel around the world. However, blackleg disease, caused by the ascomycete Leptosphaeria maculans, causes significant yield losses annually. With the recent advances in genomic technologies, the understanding of the Brassica napus-L. maculans interaction has rapidly increased, with numerous Avr and R genes cloned, setting this system up as a model organism for studying plant-pathogen associations. Although the B. napus-L. maculans interaction follows Flor's gene-for-gene hypothesis for qualitative resistance, it also puts some unique spins on the interaction. This review discusses the current status of the host-pathogen interaction and highlights some of the future gaps that need addressing moving forward.
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Affiliation(s)
- M Hossein Borhan
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan, Canada;
| | | | - Nicholas J Larkan
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan, Canada;
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Larkan NJ, Ma L, Haddadi P, Buchwaldt M, Parkin IA, Djavaheri M, Borhan MH. The Brassica napus wall-associated kinase-like (WAKL) gene Rlm9 provides race-specific blackleg resistance. Plant J 2020; 104:892-900. [PMID: 32794614 PMCID: PMC7756564 DOI: 10.1111/tpj.14966] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 07/13/2020] [Accepted: 07/21/2020] [Indexed: 05/12/2023]
Abstract
In plants, race-specific defence against microbial pathogens is facilitated by resistance (R) genes which correspond to specific pathogen avirulence genes. This study reports the cloning of a blackleg R gene from Brassica napus (canola), Rlm9, which encodes a wall-associated kinase-like (WAKL) protein, a newly discovered class of race-specific plant RLK resistance genes. Rlm9 provides race-specific resistance against isolates of Leptosphaeria maculans carrying the corresponding avirulence gene AvrLm5-9, representing only the second WAKL-type R gene described to date. The Rlm9 protein is predicted to be cell membrane-bound and while not conclusive, our work did not indicate direct interaction with AvrLm5-9. Rlm9 forms part of a distinct evolutionary family of RLK proteins in B. napus, and while little is yet known about WAKL function, the Brassica-Leptosphaeria pathosystem may prove to be a model system by which the mechanism of fungal avirulence protein recognition by WAKL-type R genes can be determined.
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Affiliation(s)
- Nicholas J. Larkan
- Armatus Genetics IncSaskatoonSKCanada
- Agriculture & Agri‐Food CanadaSaskatoonSKCanada
| | - Lisong Ma
- Agriculture & Agri‐Food CanadaSaskatoonSKCanada
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Becker MG, Haddadi P, Wan J, Adam L, Walker P, Larkan NJ, Daayf F, Borhan MH, Belmonte MF. Transcriptome Analysis of Rlm2-Mediated Host Immunity in the Brassica napus- Leptosphaeria maculans Pathosystem. Mol Plant Microbe Interact 2019; 32:1001-1012. [PMID: 30938576 DOI: 10.1094/mpmi-01-19-0028-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Our study investigated disease resistance in the Brassica napus-Leptosphaeria maculans pathosystem using a combination of laser microdissection, dual RNA sequencing, and physiological validations of large-scale gene sets. The use of laser microdissection improved pathogen detection and identified putative L. maculans effectors and lytic enzymes operative during host colonization. Within 24 h of inoculation, we detected large shifts in gene activity in resistant cotyledons associated with jasmonic acid and calcium signaling pathways that accelerated the plant defense response. Sequencing data were validated through the direct quantification of endogenous jasmonic acid levels. Additionally, resistance against L. maculans was abolished when the calcium chelator EGTA was applied to the inoculation site, providing physiological evidence of the role of calcium in B. napus immunity against L. maculans. We integrated gene expression data with all available information on cis-regulatory elements and transcription factor binding affinities to better understand the gene regulatory networks underpinning plant resistance to hemibiotrophic pathogens. These in silico analyses point to early cellular reprogramming during host immunity that are coordinated by CAMTA, BZIP, and bHLH transcription factors. Together, we provide compelling genetic and physiological evidence into the programming of plant resistance against fungal pathogens.
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Affiliation(s)
- Michael G Becker
- 1Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Parham Haddadi
- 2Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - Joey Wan
- 1Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Lorne Adam
- 3Department of Plant Science, University of Manitoba
| | - Philip Walker
- 1Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | | | - Fouad Daayf
- 3Department of Plant Science, University of Manitoba
| | - M Hossein Borhan
- 2Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - Mark F Belmonte
- 1Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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Haddadi P, Larkan NJ, Borhan MH. Dissecting R gene and host genetic background effect on the Brassica napus defense response to Leptosphaeria maculans. Sci Rep 2019; 9:6947. [PMID: 31061421 PMCID: PMC6502879 DOI: 10.1038/s41598-019-43419-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 04/01/2019] [Indexed: 12/17/2022] Open
Abstract
While our understanding of the genetics underlying the Brassica-Leptosphaeria pathosystem has advanced greatly in the last decade, differences in molecular responses due to interaction between resistance genes and host genetic background has not been studied. We applied RNAseq technology to monitor the transcriptome profiles of Brassica napus (Bn) lines carrying one of four blackleg R genes (Rlm2, Rlm3, LepR1 & LepR2) in Topas or Westar background, during the early stages of infection by a Leptosphaeria maculans (Lm) isolate carrying the corresponding Avr genes. We observed upregulation of host genes involved in hormone signalling, cell wall thickening, response to chitin and glucosinolate production in all R gene lines at 3 day after inoculation (dai) albeit having higher level of expression in LepR1 and Rlm2 than in Rlm3 and LepR2 lines. Bn-SOBIR1 (Suppressor Of BIR1-1), a receptor like kinase (RLK) that forms complex receptor like proteins (RLPs) was highly expressed in LepR1 and Rlm2 at 3 dai. In contrast Bn-SOBIR1 induction was low in Rlm3 line, which could indicate that Rlm3 may function independent of SOBIR1. Expression of Salicylic acid (SA) related defense was enhanced in LepR1 and Rlm2 at 3 dai. In contrast to SA, expression of Bn genes with homology to PDF1.2, a jasmonic acid (JA) pathway marker, were increased in all Rlm and LepR lines at 6 and 9 dai. Effect of host genetic background on induction of defense, was determined by comparison of LepR1 and LepR2 in Topas vs Westar genotype (i.e. T-LepR1 vs W-LepR1 and T-LepR2 vs W-LepR2). In both cases (regardless of R gene) overall number of defense related genes at the earliest time point (3 dai) was higher in Tops compared to Westar. SA and JA markers genes such as PR1 and PDF1.2 were more induced in Topas compared to Westar introgression lines at this time point. Even in the absence of any R gene, effect of Topas genotype in enhanced defense, was also evident by the induction of PDF1.2 that started at a low level at 3 dai and peaked at 6 and 9 dai, while no induction in Westar genotype was observed at any of these time points. Overall, variation in time and intensity of expression of genes related to defense, was clearly dependent on both R gene and the host genotype.
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Affiliation(s)
- Parham Haddadi
- Agriculture and Agri-Food Canada, Saskatoon Research and Development Centre, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada
| | | | - M Hossein Borhan
- Agriculture and Agri-Food Canada, Saskatoon Research and Development Centre, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada.
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Sari E, Bhadauria V, Ramsay L, Borhan MH, Lichtenzveig J, Bett KE, Vandenberg A, Banniza S. Defense responses of lentil (Lens culinaris) genotypes carrying non-allelic ascochyta blight resistance genes to Ascochyta lentis infection. PLoS One 2018; 13:e0204124. [PMID: 30235263 PMCID: PMC6147436 DOI: 10.1371/journal.pone.0204124] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 09/03/2018] [Indexed: 12/24/2022] Open
Abstract
Ascochyta blight of lentil is an important fungal disease in many lentil-producing regions of the world causing major yield and grain quality losses. Quick shifts in aggressiveness of the population of the causal agent Ascochyta lentis mandates developing germplasm with novel and durable resistance. In the absence of complete resistance, lentil genotypes CDC Robin and 964a-46 have frequently been used as sources of partial resistance to ascochyta blight and carry non-allelic ascochyta blight resistance genes. RNA-seq analysis was conducted to identify differences in the transcriptome of CDC Robin, 964a-46 and the susceptible check Eston after inoculation with A. lentis. Candidate defense genes differentially expressed among the genotypes had hypothetical functions in various layers of plant defense, including pathogen recognition, phytohormone signaling pathways and downstream defense responses. CDC Robin and 964a-46 activated cell surface receptors (e.g. receptor like kinases) tentatively associated with pathogen-associated molecular patterns (PAMP) recognition and nucleotide-binding site leucine-rich repeat (NBS-LRR) receptors associated with intracellular effector recognition upon A. lentis infection, and differed in their activation of salicylic acid, abscisic acid and jasmonic acid / ethylene signal transduction pathways. These differences were reflected in the differential expression of downstream defense responses such as pathogenesis-related proteins, and genes associated with the induction of cell death and cell-wall reinforcement. A significant correlation between expression levels of a selection of genes based on quantitative real-time PCR and their expression levels estimated through RNA-seq demonstrated the technical and analytical accuracy of RNA-seq for identification of genes differentially expressed among genotypes. The presence of different resistance mechanisms in 964a-46 and CDC Robin indicates their value for pyramiding gene leading to more durable resistance to ascochyta blight.
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Affiliation(s)
- Ehsan Sari
- Department of Plant Sciences/Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Vijai Bhadauria
- Department of Plant Sciences/Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Larissa Ramsay
- Department of Plant Sciences/Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - M. Hossein Borhan
- Agriculture and Agri-Food Canada, Saskatoon Research and Development Centre, Saskatoon, Saskatchewan, Canada
| | - Judith Lichtenzveig
- School of Agriculture and Environment, University of Western Australia, Perth, Western Australia, Australia
| | - Kirstin E. Bett
- Department of Plant Sciences/Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Albert Vandenberg
- Department of Plant Sciences/Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Sabine Banniza
- Department of Plant Sciences/Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- * E-mail:
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Stotz HU, Harvey PJ, Haddadi P, Mashanova A, Kukol A, Larkan NJ, Borhan MH, Fitt BDL. Genomic evidence for genes encoding leucine-rich repeat receptors linked to resistance against the eukaryotic extra- and intracellular Brassica napus pathogens Leptosphaeria maculans and Plasmodiophora brassicae. PLoS One 2018; 13:e0198201. [PMID: 29856883 PMCID: PMC5983482 DOI: 10.1371/journal.pone.0198201] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 05/15/2018] [Indexed: 01/17/2023] Open
Abstract
Genes coding for nucleotide-binding leucine-rich repeat (LRR) receptors (NLRs) control resistance against intracellular (cell-penetrating) pathogens. However, evidence for a role of genes coding for proteins with LRR domains in resistance against extracellular (apoplastic) fungal pathogens is limited. Here, the distribution of genes coding for proteins with eLRR domains but lacking kinase domains was determined for the Brassica napus genome. Predictions of signal peptide and transmembrane regions divided these genes into 184 coding for receptor-like proteins (RLPs) and 121 coding for secreted proteins (SPs). Together with previously annotated NLRs, a total of 720 LRR genes were found. Leptosphaeria maculans-induced expression during a compatible interaction with cultivar Topas differed between RLP, SP and NLR gene families; NLR genes were induced relatively late, during the necrotrophic phase of pathogen colonization. Seven RLP, one SP and two NLR genes were found in Rlm1 and Rlm3/Rlm4/Rlm7/Rlm9 loci for resistance against L. maculans on chromosome A07 of B. napus. One NLR gene at the Rlm9 locus was positively selected, as was the RLP gene on chromosome A10 with LepR3 and Rlm2 alleles conferring resistance against L. maculans races with corresponding effectors AvrLm1 and AvrLm2, respectively. Known loci for resistance against L. maculans (extracellular hemi-biotrophic fungus), Sclerotinia sclerotiorum (necrotrophic fungus) and Plasmodiophora brassicae (intracellular, obligate biotrophic protist) were examined for presence of RLPs, SPs and NLRs in these regions. Whereas loci for resistance against P. brassicae were enriched for NLRs, no such signature was observed for the other pathogens. These findings demonstrate involvement of (i) NLR genes in resistance against the intracellular pathogen P. brassicae and a putative NLR gene in Rlm9-mediated resistance against the extracellular pathogen L. maculans.
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Affiliation(s)
- Henrik U. Stotz
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
- * E-mail:
| | - Pascoe J. Harvey
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
| | - Parham Haddadi
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada
| | - Alla Mashanova
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
| | - Andreas Kukol
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
| | | | - M. Hossein Borhan
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada
| | - Bruce D. L. Fitt
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
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Ma L, Djavaheri M, Wang H, Larkan NJ, Haddadi P, Beynon E, Gropp G, Borhan MH. Leptosphaeria maculans Effector Protein AvrLm1 Modulates Plant Immunity by Enhancing MAP Kinase 9 Phosphorylation. iScience 2018; 3:177-191. [PMID: 30428318 PMCID: PMC6137710 DOI: 10.1016/j.isci.2018.04.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 03/22/2018] [Accepted: 04/16/2018] [Indexed: 01/03/2023] Open
Abstract
Leptosphaeria maculans, the causal agent of blackleg disease in canola (Brassica napus), secretes an array of effectors into the host to overcome host defense. Here we present evidence that the L. maculans effector protein AvrLm1 functions as a virulence factor by interacting with the B. napus mitogen-activated protein (MAP) kinase 9 (BnMPK9), resulting in increased accumulation and enhanced phosphorylation of the host protein. Transient expression of BnMPK9 in Nicotiana benthamiana induces cell death, and this phenotype is enhanced in the presence of AvrLm1, suggesting that induction of cell death due to enhanced accumulation and phosphorylation of BnMPK9 by AvrLm1 supports the initiation of necrotrophic phase of L. maculans infection. Stable expression of BnMPK9 in B. napus perturbs hormone signaling, notably salicylic acid response genes, to facilitate L. maculans infection. Our findings provide evidence that a MAP kinase is directly targeted by a fungal effector to modulate plant immunity. Leptosphaeria maculans effector AvrLm1 interacts with the Brassica napus MPK9 (BnMPK9) AvrLm1 increases the accumulation and enhances the phosphorylation of BnMPK9 AvrLm1 enhances BnMPK9-dependent cell death in Nicotiana benthamiana Stable expression of BnMPK9 in B. napus facilitates L. maculans infection
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Affiliation(s)
- Lisong Ma
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - Mohammad Djavaheri
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - Haiyan Wang
- Center of Plant Disease and Plant Pests of Hebei Province, College of Plant Protection, Hebei Agricultural University, Baoding 071001, China
| | - Nicholas J Larkan
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada; Armatus Genetics Inc., Saskatoon, SK S7J 4M2, Canada
| | - Parham Haddadi
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - Elena Beynon
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - Gordon Gropp
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
| | - M Hossein Borhan
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada.
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Seifbarghi S, Borhan MH, Wei Y, Coutu C, Robinson SJ, Hegedus DD. Changes in the Sclerotinia sclerotiorum transcriptome during infection of Brassica napus. BMC Genomics 2017; 18:266. [PMID: 28356071 PMCID: PMC5372324 DOI: 10.1186/s12864-017-3642-5] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 03/18/2017] [Indexed: 11/17/2022] Open
Abstract
Background Sclerotinia sclerotiorum causes stem rot in Brassica napus, which leads to lodging and severe yield losses. Although recent studies have explored significant progress in the characterization of individual S. sclerotiorum pathogenicity factors, a gap exists in profiling gene expression throughout the course of S. sclerotiorum infection on a host plant. In this study, RNA-Seq analysis was performed with focus on the events occurring through the early (1 h) to the middle (48 h) stages of infection. Results Transcript analysis revealed the temporal pattern and amplitude of the deployment of genes associated with aspects of pathogenicity or virulence during the course of S. sclerotiorum infection on Brassica napus. These genes were categorized into eight functional groups: hydrolytic enzymes, secondary metabolites, detoxification, signaling, development, secreted effectors, oxalic acid and reactive oxygen species production. The induction patterns of nearly all of these genes agreed with their predicted functions. Principal component analysis delineated gene expression patterns that signified transitions between pathogenic phases, namely host penetration, ramification and necrotic stages, and provided evidence for the occurrence of a brief biotrophic phase soon after host penetration. Conclusions The current observations support the notion that S. sclerotiorum deploys an array of factors and complex strategies to facilitate host colonization and mitigate host defenses. This investigation provides a broad overview of the sequential expression of virulence/pathogenicity-associated genes during infection of B. napus by S. sclerotiorum and provides information for further characterization of genes involved in the S. sclerotiorum-host plant interactions. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3642-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shirin Seifbarghi
- Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada.,Department of Biology, University of Saskatchewan, Saskatoon, Canada
| | - M Hossein Borhan
- Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada
| | - Yangdou Wei
- Department of Biology, University of Saskatchewan, Saskatoon, Canada
| | - Cathy Coutu
- Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada
| | - Stephen J Robinson
- Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada
| | - Dwayne D Hegedus
- Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada. .,Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, Canada.
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Larkan NJ, Yu F, Lydiate DJ, Rimmer SR, Borhan MH. Single R Gene Introgression Lines for Accurate Dissection of the Brassica - Leptosphaeria Pathosystem. Front Plant Sci 2016; 7:1771. [PMID: 27965684 PMCID: PMC5124708 DOI: 10.3389/fpls.2016.01771] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 11/10/2016] [Indexed: 05/18/2023]
Abstract
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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Affiliation(s)
- Nicholas J. Larkan
- Saskatoon Research Centre, Agriculture and Agri-Food CanadaSaskatoon, SK, Canada
- Armatus Genetics Inc.Saskatoon, SK, Canada
| | - Fengqun Yu
- Saskatoon Research Centre, Agriculture and Agri-Food CanadaSaskatoon, SK, Canada
| | - Derek J. Lydiate
- Saskatoon Research Centre, Agriculture and Agri-Food CanadaSaskatoon, SK, Canada
| | - S. Roger Rimmer
- Saskatoon Research Centre, Agriculture and Agri-Food CanadaSaskatoon, SK, Canada
| | - M. Hossein Borhan
- Saskatoon Research Centre, Agriculture and Agri-Food CanadaSaskatoon, SK, Canada
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Haddadi P, Ma L, Wang H, Borhan MH. Genome-wide transcriptomic analyses provide insights into the lifestyle transition and effector repertoire of Leptosphaeria maculans during the colonization of Brassica napus seedlings. Mol Plant Pathol 2016; 17:1196-210. [PMID: 26679637 PMCID: PMC6638455 DOI: 10.1111/mpp.12356] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 11/18/2015] [Accepted: 12/11/2015] [Indexed: 05/08/2023]
Abstract
Molecular interaction between the causal agent of blackleg disease, Leptosphaeria maculans (Lm), and its host, Brassica napus, is largely unknown. We applied a deep RNA-sequencing approach to gain insight into the pathogenicity mechanisms of Lm and the defence response of B. napus. RNA from the infected susceptible B. napus cultivar Topas DH16516, sampled at 2-day intervals (0-8 days), was sequenced and used for gene expression profiling. Patterns of gene expression regulation in B. napus showed multifaceted defence responses evident by the differential expression of genes encoding the pattern recognition receptor CERK1 (chitin elicitor receptor kinase 1), receptor like proteins and WRKY transcription factors. The up-regulation of genes related to salicylic acid and jasmonic acid at the initial and late stages of infection, respectively, provided evidence for the biotrophic and necrotrophic life stages of Lm during the infection of B. napus cotyledons. Lm transition from biotrophy to necrotropy was also supported by the expression function of Lm necrosis and ethylene-inducing (Nep-1)-like peptide. Genes encoding polyketide synthases and non-ribosomal peptide synthetases, with potential roles in pathogenicity, were up-regulated at 6-8 days after inoculation. Among other plant defence-related genes differentially regulated in response to Lm infection were genes involved in the reinforcement of the cell wall and the production of glucosinolates. Dual RNA-sequencing allowed us to define the Lm candidate effectors expressed during the infection of B. napus. Several candidate effectors suppressed Bax-induced cell death when transiently expressed in Nicotiana benthamaina leaves.
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Affiliation(s)
- Parham Haddadi
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, SK, Canada, S7N 0X2
| | - Lisong Ma
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, SK, Canada, S7N 0X2
| | - Haiyan Wang
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, SK, Canada, S7N 0X2
- Center of Plant Disease and Plant Pests of Hebei Province, College of Plant Protection, Agricultural University of Hebei, Baoding, China, 071001
| | - M Hossein Borhan
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, SK, Canada, S7N 0X2.
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Larkan NJ, Raman H, Lydiate DJ, Robinson SJ, Yu F, Barbulescu DM, Raman R, Luckett DJ, Burton W, Wratten N, Salisbury PA, Rimmer SR, Borhan MH. Multi-environment QTL studies suggest a role for cysteine-rich protein kinase genes in quantitative resistance to blackleg disease in Brassica napus. BMC Plant Biol 2016; 16:183. [PMID: 27553246 PMCID: PMC4995785 DOI: 10.1186/s12870-016-0877-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 08/17/2016] [Indexed: 05/18/2023]
Abstract
BACKGROUND Resistance to the blackleg disease of Brassica napus (canola/oilseed rape), caused by the hemibiotrophic fungal pathogen Leptosphaeria maculans, is determined by both race-specific resistance (R) genes and quantitative resistance loci (QTL), or adult-plant resistance (APR). While the introgression of R genes into breeding material is relatively simple, QTL are often detected sporadically, making them harder to capture in breeding programs. For the effective deployment of APR in crop varieties, resistance QTL need to have a reliable influence on phenotype in multiple environments and be well defined genetically to enable marker-assisted selection (MAS). RESULTS Doubled-haploid populations produced from the susceptible B. napus variety Topas and APR varieties AG-Castle and AV-Sapphire were analysed for resistance to blackleg in two locations over 3 and 4 years, respectively. Three stable QTL were detected in each population, with two loci appearing to be common to both APR varieties. Physical delineation of three QTL regions was sufficient to identify candidate defense-related genes, including a cluster of cysteine-rich receptor-like kinases contained within a 49 gene QTL interval on chromosome A01. Individual L. maculans isolates were used to define the physical intervals for the race-specific R genes Rlm3 and Rlm4 and to identify QTL common to both field studies and the cotyledon resistance response. CONCLUSION Through multi-environment QTL analysis we have identified and delineated four significant and stable QTL suitable for MAS of quantitative blackleg resistance in B. napus, and identified candidate genes which potentially play a role in quantitative defense responses to L. maculans.
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Affiliation(s)
- Nicholas J. Larkan
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK S7N 0X2 Canada
- Armatus Genetics Inc, Saskatoon, SK S7W 0C9 Canada
| | - Harsh Raman
- Graham Centre for Agricultural Innovation (an alliance between Charles Sturt University and NSW Department of Primary Industries), Wagga Wagga Agricultural Institute, Wagga Wagga, NSW 2650 Australia
| | - Derek J. Lydiate
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK S7N 0X2 Canada
| | - Stephen J. Robinson
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK S7N 0X2 Canada
| | - Fengqun Yu
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK S7N 0X2 Canada
| | - Denise M. Barbulescu
- Department of Economic Development, Jobs, Transport and Resources, Grains Innovation Park, Horsham, VIC 3400 Australia
| | - Rosy Raman
- Graham Centre for Agricultural Innovation (an alliance between Charles Sturt University and NSW Department of Primary Industries), Wagga Wagga Agricultural Institute, Wagga Wagga, NSW 2650 Australia
| | - David J. Luckett
- Graham Centre for Agricultural Innovation (an alliance between Charles Sturt University and NSW Department of Primary Industries), Wagga Wagga Agricultural Institute, Wagga Wagga, NSW 2650 Australia
| | - Wayne Burton
- Department of Economic Development, Jobs, Transport and Resources, Grains Innovation Park, Horsham, VIC 3400 Australia
- Seednet Australia, Golf Course Road, Horsham, VIC 3402 Australia
| | - Neil Wratten
- Graham Centre for Agricultural Innovation (an alliance between Charles Sturt University and NSW Department of Primary Industries), Wagga Wagga Agricultural Institute, Wagga Wagga, NSW 2650 Australia
| | - Philip A. Salisbury
- Department of Economic Development, Jobs, Transport and Resources, Centre for AgriBioscience, La Trobe University, Bundoora, VIC 3083 Australia
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC 3010 Australia
| | - S. Roger Rimmer
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK S7N 0X2 Canada
| | - M. Hossein Borhan
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK S7N 0X2 Canada
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Rolfe SA, Strelkov SE, Links MG, Clarke WE, Robinson SJ, Djavaheri M, Malinowski R, Haddadi P, Kagale S, Parkin IAP, Taheri A, Borhan MH. The compact genome of the plant pathogen Plasmodiophora brassicae is adapted to intracellular interactions with host Brassica spp. BMC Genomics 2016; 17:272. [PMID: 27036196 PMCID: PMC4815078 DOI: 10.1186/s12864-016-2597-2] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 03/16/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The protist Plasmodiophora brassicae is a soil-borne pathogen of cruciferous species and the causal agent of clubroot disease of Brassicas including agriculturally important crops such as canola/rapeseed (Brassica napus). P. brassicae has remained an enigmatic plant pathogen and is a rare example of an obligate biotroph that resides entirely inside the host plant cell. The pathogen is the cause of severe yield losses and can render infested fields unsuitable for Brassica crop growth due to the persistence of resting spores in the soil for up to 20 years. RESULTS To provide insight into the biology of the pathogen and its interaction with its primary host B. napus, we produced a draft genome of P. brassicae pathotypes 3 and 6 (Pb3 and Pb6) that differ in their host range. Pb3 is highly virulent on B. napus (but also infects other Brassica species) while Pb6 infects only vegetable Brassica crops. Both the Pb3 and Pb6 genomes are highly compact, each with a total size of 24.2 Mb, and contain less than 2 % repetitive DNA. Clustering of genome-wide single nucleotide polymorphisms (SNP) of Pb3, Pb6 and three additional re-sequenced pathotypes (Pb2, Pb5 and Pb8) shows a high degree of correlation of cluster grouping with host range. The Pb3 genome features significant reduction of intergenic space with multiple examples of overlapping untranslated regions (UTRs). Dependency on the host for essential nutrients is evident from the loss of genes for the biosynthesis of thiamine and some amino acids and the presence of a wide range of transport proteins, including some unique to P. brassicae. The annotated genes of Pb3 include those with a potential role in the regulation of the plant growth hormones cytokinin and auxin. The expression profile of Pb3 genes, including putative effectors, during infection and their potential role in manipulation of host defence is discussed. CONCLUSION The P. brassicae genome sequence reveals a compact genome, a dependency of the pathogen on its host for some essential nutrients and a potential role in the regulation of host plant cytokinin and auxin. Genome annotation supported by RNA sequencing reveals significant reduction in intergenic space which, in addition to low repeat content, has likely contributed to the P. brassicae compact genome.
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Affiliation(s)
- Stephen A. Rolfe
- />Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN UK
| | - Stephen E. Strelkov
- />Department of Agricultural, Food and Nutritional Science, University of Alberta, 410 Agriculture/Forestry Centre, Edmonton, AB T6G 2P5 Canada
| | - Matthew G. Links
- />Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2 Canada
| | - Wayne E. Clarke
- />Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2 Canada
- />Present address: New York Genome Center, 101 6th Ave, New York, NY 10013 USA
| | - Stephen J. Robinson
- />Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2 Canada
| | - Mohammad Djavaheri
- />Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2 Canada
| | - Robert Malinowski
- />Department of Integrative Plant Biology, Institute of Plant Genetics of the Polish Academy of Sciences, ul. Strzeszynska 34, 60-479 Poznan, Poland
| | - Parham Haddadi
- />Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2 Canada
| | - Sateesh Kagale
- />National Research Council Canada, 110 Gymnasium Place, Saskatoon, SK, S7N 0W9 Canada
| | - Isobel A. P. Parkin
- />Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2 Canada
| | - Ali Taheri
- />Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2 Canada
- />Present address: Department of Agricultural and Environmental Sciences, College of Agriculture, Human and Natural Sciences, Tennessee State University, 3500 John A Merritt Blvd, Nashville, TN 37209 USA
| | - M. Hossein Borhan
- />Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2 Canada
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Sonah H, Zhang X, Deshmukh RK, Borhan MH, Fernando WGD, Bélanger RR. Comparative Transcriptomic Analysis of Virulence Factors in Leptosphaeria maculans during Compatible and Incompatible Interactions with Canola. Front Plant Sci 2016; 7:1784. [PMID: 27990146 PMCID: PMC5131014 DOI: 10.3389/fpls.2016.01784] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 11/11/2016] [Indexed: 05/08/2023]
Abstract
Leptosphaeria maculans is a hemibiotrophic fungus that causes blackleg of canola (Brassica napus), one of the most devastating diseases of this crop. In the present study, transcriptome profiling of L. maculans was performed in an effort to understand and define the pathogenicity genes that govern both the biotrophic and the necrotrophic phase of the fungus, as well as those that separate a compatible from an incompatible interaction. For this purpose, comparative RNA-seq analyses were performed on L. maculans isolate D5 at four different time points following inoculation on susceptible cultivar Topas-DH16516 or resistant introgression line Topas-Rlm2. Analysis of 1.6 billion Illumina reads readily identified differentially expressed genes that were over represented by candidate secretory effector proteins, CAZymes, and other pathogenicity genes. Comparisons between the compatible and incompatible interactions led to the identification of 28 effector proteins whose chronology and level of expression suggested a role in the establishment and maintenance of biotrophy with the plant. These included all known Avr genes of isolate D5 along with eight newly characterized effectors. In addition, another 15 effector proteins were found to be exclusively expressed during the necrotrophic phase of the fungus, which supports the concept that L. maculans has a separate and distinct arsenal contributing to each phase. As for CAZymes, they were often highly expressed at 3 dpi but with no difference in expression between the compatible and incompatible interactions, indicating that other factors were necessary to determine the outcome of the interaction. However, their significantly higher expression at 11 dpi in the compatible interaction confirmed that they contributed to the necrotrophic phase of the fungus. A notable exception was LysM genes whose high expression was singularly observed on the susceptible host at 7 dpi. In the case of TFs, their higher expression at 7 and 11 dpi on susceptible Topas support an important role in regulating the genes involved in the different pathogenic phases of L. maculans. In conclusion, comparison of the transcriptome of L. maculans during compatible and incompatible interactions has led to the identification of key pathogenicity genes that regulate not only the fate of the interaction but also lifestyle transitions of the fungus.
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Affiliation(s)
- Humira Sonah
- Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université LavalQuébec QC, Canada
| | - Xuehua Zhang
- Department of Plant Science, University of Manitoba WinnipegWinnipeg, MB, Canada
| | - Rupesh K. Deshmukh
- Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université LavalQuébec QC, Canada
| | | | | | - Richard R. Bélanger
- Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université LavalQuébec QC, Canada
- *Correspondence: Richard R. Bélanger
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Ghanbarnia K, Fudal I, Larkan NJ, Links MG, Balesdent MH, Profotova B, Fernando WGD, Rouxel T, Borhan MH. Rapid identification of the Leptosphaeria maculans avirulence gene AvrLm2 using an intraspecific comparative genomics approach. Mol Plant Pathol 2015; 16:699-709. [PMID: 25492575 PMCID: PMC6638346 DOI: 10.1111/mpp.12228] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Five avirulence genes from Leptosphaeria maculans, the causal agent of blackleg of canola (Brassica napus), have been identified previously through map-based cloning. In this study, a comparative genomic approach was used to clone the previously mapped AvrLm2. Given the lack of a presence-absence gene polymorphism coincident with the AvrLm2 phenotype, 36 L. maculans isolates were resequenced and analysed for single-nucleotide polymorphisms (SNPs) in predicted small secreted protein-encoding genes present within the map interval. Three SNPs coincident with the AvrLm2 phenotype were identified within LmCys1, previously identified as a putative effector-coding gene. Complementation of a virulent isolate with LmCys1, as the candidate AvrLm2 allele, restored the avirulent phenotype on Rlm2-containing B. napus lines. AvrLm2 encodes a small cysteine-rich protein with low similarity to other proteins in the public databases. Unlike other avirulence genes, AvrLm2 resides in a small GC island within an AT-rich isochore of the genome, and was never found to be deleted completely in virulent isolates.
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Affiliation(s)
- Kaveh Ghanbarnia
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada, S7N 0X2
- Department of Plant Science, University of Manitoba, Winnipeg, MB, Canada, R3T 2N2
| | | | - Nicholas J Larkan
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada, S7N 0X2
| | - Matthew G Links
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada, S7N 0X2
- Department of Computer Science, University of Saskatchewan, Saskatoon, SK, Canada, S7N 5C9
| | | | | | | | | | - M Hossein Borhan
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada, S7N 0X2
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16
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Ma L, Borhan MH. The receptor-like kinase SOBIR1 interacts with Brassica napus LepR3 and is required for Leptosphaeria maculans AvrLm1-triggered immunity. Front Plant Sci 2015; 6:933. [PMID: 26579176 PMCID: PMC4625043 DOI: 10.3389/fpls.2015.00933] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 10/15/2015] [Indexed: 05/07/2023]
Abstract
The fungus Leptosphaeria maculans (L. maculans) is the causal agent of blackleg disease of canola/oilseed rape (Brassica napus) worldwide. We previously reported cloning of the B. napus blackleg resistance gene, LepR3, which encodes a receptor-like protein. LepR3 triggers localized cell death upon recognition of its cognate Avr protein, AvrLm1. Here, we exploited the Nicotiana benthamiana model plant to investigate the recognition mechanism of AvrLm1 by LepR3. Co-expression of the LepR3/AvrLm1 gene pair in N. benthamiana resulted in development of a hypersensitive response (HR). However, a truncated AvrLm1 lacking its indigenous signal peptide was compromised in its ability to induce LepR3-mediated HR, indicating that AvrLm1 is perceived by LepR3 extracellularly. Structure-function analysis of the AvrLm1 protein revealed that the C-terminal region of AvrLm1 was required for LepR3-mediated HR in N. benthamiana and for resistance to L. maculans in B. napus. LepR3 was shown to be physically interacting with the B. napus receptor like kinase, SOBIR1 (BnSOBIR1). Silencing of NbSOBIR1 or NbSERK3 (BAK1) compromised LepR3-AvrLm1-dependent HR in N. benthamiana, suggesting that LepR3-mediated resistance to L. maculans in B. napus requires SOBIR1 and BAK1/SERK3. Using this model system, we determined that BnSOBIR1 and SERK3/BAK1 are essential partners in the LepR3 signaling complex and were able to define the AvrLm1 effector domain.
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17
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Larkan NJ, Lydiate DJ, Yu F, Rimmer SR, Borhan MH. Co-localisation of the blackleg resistance genes Rlm2 and LepR3 on Brassica napus chromosome A10. BMC Plant Biol 2014; 14:387. [PMID: 25551287 PMCID: PMC4302512 DOI: 10.1186/s12870-014-0387-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 12/15/2014] [Indexed: 05/18/2023]
Abstract
BACKGROUND The protection of canola (Brassica napus) crops against blackleg disease, caused by the fungal pathogen Leptosphaeria maculans, is largely mediated by race-specific resistance genes (R-genes). While many R-genes effective against blackleg disease have been identified in Brassica species, information of the precise genomic locations of the genes is limited. RESULTS In this study, the Rlm2 gene for resistance to blackleg, located on chromosome A10 of the B. napus cultivar 'Glacier', was targeted for fine mapping. Molecular markers tightly linked to the gene were developed for use in mapping the resistance locus and defining the physical interval in B. napus. Rlm2 was localised to a 5.8 cM interval corresponding to approximately 873 kb of the B. napus chromosome A10. CONCLUSION The recently-cloned B. napus R-gene, LepR3, occupies the same region of A10 as Rlm2 and analysis of the putative B. napus and B. rapa genes in the homologous region identified several additional candidate defense-related genes that may control Rlm2 function.
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Affiliation(s)
- Nicholas J Larkan
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, S7N 0X2 SK Canada
| | - Derek J Lydiate
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, S7N 0X2 SK Canada
| | - Fengqun Yu
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, S7N 0X2 SK Canada
| | - S Roger Rimmer
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, S7N 0X2 SK Canada
| | - M Hossein Borhan
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, S7N 0X2 SK Canada
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Larkan NJ, Lydiate DJ, Parkin IAP, Nelson MN, Epp DJ, Cowling WA, Rimmer SR, Borhan MH. The Brassica napus blackleg resistance gene LepR3 encodes a receptor-like protein triggered by the Leptosphaeria maculans effector AVRLM1. New Phytol 2013; 197:595-605. [PMID: 23206118 DOI: 10.1111/nph.12043] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 10/05/2012] [Indexed: 05/18/2023]
Abstract
LepR3, found in the Brassica napus cv 'Surpass 400', provides race-specific resistance to the fungal pathogen Leptosphaeria maculans, which was overcome after great devastation in Australia in 2004. We investigated the LepR3 locus to identify the genetic basis of this resistance interaction. We employed a map-based cloning strategy, exploiting collinearity with the Arabidopsis thaliana and Brassica rapa genomes to enrich the map and locate a candidate gene. We also investigated the interaction of LepR3 with the L. maculans avirulence gene AvrLm1 using transgenics. LepR3 was found to encode a receptor-like protein (RLP). We also demonstrated that avirulence towards LepR3 is conferred by AvrLm1, which is responsible for both the Rlm1 and LepR3-dependent resistance responses in B. napus. LepR3 is the first functional B. napus disease resistance gene to be cloned. AvrLm1's interaction with two independent resistance loci, Rlm1 and LepR3, highlights the need to consider redundant phenotypes in 'gene-for-gene' interactions and offers an explanation as to why LepR3 was overcome so rapidly in parts of Australia.
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Affiliation(s)
- N J Larkan
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, Canada, S7N 0X2
- School of Plant Biology, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - D J Lydiate
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, Canada, S7N 0X2
| | - I A P Parkin
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, Canada, S7N 0X2
| | - M N Nelson
- School of Plant Biology, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
- The UWA Institute of Agriculture, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - D J Epp
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, Canada, S7N 0X2
| | - W A Cowling
- The UWA Institute of Agriculture, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - S R Rimmer
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, Canada, S7N 0X2
| | - M H Borhan
- Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, Canada, S7N 0X2
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Borhan MH, Gunn N, Cooper A, Gulden S, Tör M, Rimmer SR, Holub EB. WRR4 encodes a TIR-NB-LRR protein that confers broad-spectrum white rust resistance in Arabidopsis thaliana to four physiological races of Albugo candida. Mol Plant Microbe Interact 2008; 21:757-68. [PMID: 18624640 DOI: 10.1094/mpmi-21-6-0757] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
White blister rust in the Brassicaceae is emerging as a superb model for exploring how plant biodiversity has channeled speciation of biotrophic parasites. The causal agents of white rust across a wide breadth of cruciferous hosts currently are named as variants of a single oomycete species, Albugo candida. The most notable examples include a major group of physiological races that each are economically destructive in a different vegetable or oilseed crop of Brassica juncea (A. candida race 2), B. rapa (race 7), or B. oleracea (race 9); or parasitic on wild crucifers such as Capsella bursa-pastoris (race 4). Arabidopsis thaliana is innately immune to these races of A. candida under natural conditions; however, it commonly hosts its own molecularly distinct subspecies of A. candida (A. candida subsp. arabidopsis). In the laboratory, we have identified several accessions of Arabidopsis thaliana (e.g.,. Ws-3) that can permit varying degrees of rust development following inoculation with A. candida races 2, 4, and 7, whereas race 9 is universally incompatible in Arabidopsis thaliana and nonrusting resistance is the most prevalent outcome of interactions with the other races. Subtle variation in resistance phenotypes is evident, observed initially with an isolate of A. candida race 4, indicating additional genetic variation. Therefore, we used the race 4 isolate for map-based cloning of the first of many expected white rust resistance (WRR) genes. This gene was designated WRR4 and encodes a cytoplasmic toll-interleukin receptor-like nucleotide-binding leucine-rich repeat receptor-like protein that confers a dominant, broad-spectrum white rust resistance in the Arabidopsis thaliana accession Columbia to representative isolates of A. candida races 2, 4, 7, and 9, as verified by transgenic expression of the Columbia allele in Ws-3. The WRR4 protein requires functional expression of the lipase-like protein EDS1 but not the paralogous protein PAD4, and confers full immunity that masks an underlying nonhypersensitive incompatibility in Columbia to A. candida race 4. This residual incompatibility is independent of functional EDS1.
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Affiliation(s)
- M Hossein Borhan
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, SK., S7N 0X2, Canada
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Borhan MH, Brose E, Beynon JL, Holub EB. White rust (Albugo candida) resistance loci on three Arabidopsis chromosomes are closely linked to downy mildew (Peronospora parasitica) resistance loci. Mol Plant Pathol 2001; 2:87-95. [PMID: 20572995 DOI: 10.1046/j.1364-3703.2001.00056.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Summary Two accessions of Arabidopsis thaliana (Ksk-1 and Ksk-2) were used to identify and map three loci (RAC1, RAC2 and RAC3) of genes that confer Resistance to Albugo candida (white rust). The phenotypes associated with these genes were classified as either FN (necrotic flecks on upper surface of cotyledons and no blisters) for RAC2 and RAC3, or FYN (flecks surrounded by yellowing and no blisters) for RAC1. Both phenotypes exhibited rapid death of host cells penetrated by the parasite (hypersensitive response), with callose deposition commonly encasing the haustorium. F(6) recombinant inbred lines were produced specifically for the purpose of mapping each RAC locus relative to molecular markers. Dominant resistance at the locus RAC1 in Ksk-1 was previously mapped to chromosome 1 between RFLP markers m253 and m254, and co-segregating with a downy mildew resistance specificity RPP9 in the accession Wei-0. We report here a fine-scale map interval and co-segregating markers for this locus, which in turn enabled mapping of a previously unnoticed source of resistance in Ksk-1 designated RAC3 that exhibits an FN phenotype hyperstatic to the FYN phenotype of RAC1. RAC3 is closely linked to the RPP8/HRT on chromosome 5, a locus which contains specificities for resistance to downy mildew and turnip crinkle virus. Recombinant inbreds also enabled mapping of recessive resistance at RAC2 in Ksk-2 to the bottom arm of chromosome 3, in the 6 cM interval between two downy mildew resistance loci (RPP1 and RPP13).
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Affiliation(s)
- M H Borhan
- Agriculture and Agri-Food Canada, Saskatoon Research Center, Saskatoon, SK, S7N OX2, Canada
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