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Dr. Dilantha Fernando is a Dean, professor, and plant pathologist at the University of Manitoba, Canada. Dr. Fernando received his Ph.D. from Oregon State University USA. Dilantha was elected a Fellow of the American Phytopathological Society in the USA, in 2019. Dilantha was awarded the highest award from the Canadian Phytopathological Society in 2020—the CPS Award for Outstanding Research. Dilantha also received an award for exemplary research towards sustainable agriculture in 2019 from the International PGPR Community. Dilantha is the current immediate Past-President of the Canadian Phytopathological Society. Dr. Fernando is a world authority on host-pathogen interaction studies and works mainly on canola and wheat diseases. He is a featured keynote or invited speaker at many international conferences. Dr. Fernando has been internationally recognized with awards for excellence in research, teaching, and service. He has published 165 peer-reviewed papers and 14 book chapters. Professor Fernando has developed 38 canola cultivars with his co-developers. Professor Fernando has trained over 75 graduate students and postdoctoral scientists at the University of Manitoba and another 68 undergraduate students. He is an editor of 6 international journals and editor in chief of one.
Plants, unlike animals, lack specialized mobile immune cells, so they do not have an adaptive immune system. Instead, plants can launch specific, self-tolerant immune responses and establish immune memory. Plants possess defence mechanisms that efficiently detect and ward off potentially dangerous microorganisms. These defence mechanisms start with multiple signalling processes responsible for sensation, recognition, signal collection, and conveying information between cells. Recognition occurs when microbial or pathogen-associated molecular patterns (MAMPs or PAMPs) are detected, leading to MAMP- or PAMP-triggered immunity (MTI or PTI). Plant cells also recognize pathogens through effector-triggered immunity (ETI), which relies on the function of the pathogen’s avirulence (Avr) gene-coded effector proteins and host’s resistance (R) gene-coded R proteins, resulting in the activation of apoptosis-like cell death, known as the hypersensitive response. In addition, reactive oxygen species (ROS) act as a double-edged sword; they are either toxic or versatile signalling molecules in plants. ROS generation is an integral part of hormone regulation and function in plant defence mechanisms. Plant hormones are also implicated in plant defence signalling pathways; salicylic acid, jasmonic acid, and ethylene have been increasingly studied in plant responses to pathogens. These innate immune system components interact with each other and provide protection against invading pathogens. We review advances in understanding the molecular aspects of plant defence mechanisms and describe the role of ROS, mitogen-activated protein kinase (MAPK) cascades, and hormones in modulating defence responses. We also provide an overview of how these plant defence components interact for a balanced and appropriate defence response.
Cunchun Yang; Aria Dolatabadian; W.G. Dilantha Fernando. The wonderful world of intrinsic and intricate immunity responses in plants against pathogens. Canadian Journal of Plant Pathology 2021, 1 .
AMA StyleCunchun Yang, Aria Dolatabadian, W.G. Dilantha Fernando. The wonderful world of intrinsic and intricate immunity responses in plants against pathogens. Canadian Journal of Plant Pathology. 2021; ():1.
Chicago/Turabian StyleCunchun Yang; Aria Dolatabadian; W.G. Dilantha Fernando. 2021. "The wonderful world of intrinsic and intricate immunity responses in plants against pathogens." Canadian Journal of Plant Pathology , no. : 1.
Blackleg, caused by the fungal pathogen Leptosphaeria maculans, is a serious threat to canola (Brassica napus L.) production in western Canada. Crop scouting and extended crop rotation, along with the use of effective genetic resistance, have been key management practices available to mitigate the impact of the disease. In recent years, new pathogen races have reduced the effectiveness of some of the resistant cultivars deployed. Strategic deployment and rotation of major resistance (R) genes in cultivars have been used in France and Australia to help increase the longevity of blackleg resistance. Canada also introduced a grouping system in 2017 to identify blackleg R genes in canola cultivars. The main objective of this study was to examine and validate the concept of R gene deployment through monitoring the avirulence (Avr) profile of L. maculans population and disease levels in commercial canola fields within the Canadian prairies. Blackleg disease incidence and severity was collected from 146 cultivars from 53 sites across Manitoba, Saskatchewan, and Alberta in 2018 and 2019, and the results varied significantly between gene groups, which is likely influenced by the pathogen population. Isolates collected from spring and fall stubble residues were examined for the presence of Avr alleles AvrLm1, AvrLm2, AvrLm3, AvrLm4, AvrLm5, AvrLm6, AvrLm7, AvrLm9, AvrLm10, AvrLm11, AvrLepR1, AvrLepR2, AvrLep3, and AvrLmS using a set of differential host genotypes carrying known resistance genes or PCR-based markers. The Simpson’s evenness index was very low, due to two dominant L. maculans races (AvrLm2-4-5-6-7-10-11 and AvrLm2-5-6-7-10-11) representing 49% of the population, but diversity of the population was high from the 35 L. maculans races isolated in Manitoba. AvrLm6 and AvrLm11 were found in all 254 L. maculans isolates collected in Manitoba. Knowledge of the blackleg disease levels in relation to the R genes deployed, along with the L. maculans Avr profile, helps to measure the effectiveness of genetic resistance.
Justine Cornelsen; Zhongwei Zou; Shuanglong Huang; Paula Parks; Ralph Lange; Gary Peng; W. G. Dilantha Fernando. Validating the Strategic Deployment of Blackleg Resistance Gene Groups in Commercial Canola Fields on the Canadian Prairies. Frontiers in Plant Science 2021, 12, 1 .
AMA StyleJustine Cornelsen, Zhongwei Zou, Shuanglong Huang, Paula Parks, Ralph Lange, Gary Peng, W. G. Dilantha Fernando. Validating the Strategic Deployment of Blackleg Resistance Gene Groups in Commercial Canola Fields on the Canadian Prairies. Frontiers in Plant Science. 2021; 12 ():1.
Chicago/Turabian StyleJustine Cornelsen; Zhongwei Zou; Shuanglong Huang; Paula Parks; Ralph Lange; Gary Peng; W. G. Dilantha Fernando. 2021. "Validating the Strategic Deployment of Blackleg Resistance Gene Groups in Commercial Canola Fields on the Canadian Prairies." Frontiers in Plant Science 12, no. : 1.
An oxidative burst is an early response of plants to various biotic/abiotic stresses. In plant-microbe interactions, the plant body can induce oxidative burst to activate various defense mechanisms to combat phytopathogens. A localized oxidative burst is also one of the typical behaviors during hypersensitive response (HR) caused by gene-for-gene interaction. In this study, the occurrence of oxidative burst and its signaling pathways was studied from different levels of disease severity (i.e., susceptible, intermediate, and resistant) in the B. napus–L. maculans pathosystem. Canola cotyledons with distinct levels of resistance exhibited differential regulation of the genes involved in reactive oxygen species (ROS) accumulation and responses. Histochemical assays were carried out to understand the patterns of H2O2 accumulation and cell death. Intermediate and resistant genotypes exhibited earlier accumulation of H2O2 and emergence of cell death around the inoculation origins. The observations also suggested that the cotyledons with stronger resistance were able to form a protective region of intensive oxidative bursts between the areas with and without hyphal intrusions to block further fungal advancement to the uninfected regions. The qPCR analysis suggested that different onset patterns of some marker genes in ROS accumulation/programmed cell death (PCD) such as RBOHD, MPK3 were associated with distinct levels of resistance from B. napus cultivars against L. maculans. The observations and datasets from this article indicated the distinct differences in ROS-related cellular behaviors and signaling between compatible and incompatible interactions.
Cunchun Yang; W. Fernando. Analysis of the Oxidative Burst and Its Relevant Signaling Pathways in Leptosphaeria maculans—Brassica napus Pathosystem. International Journal of Molecular Sciences 2021, 22, 4812 .
AMA StyleCunchun Yang, W. Fernando. Analysis of the Oxidative Burst and Its Relevant Signaling Pathways in Leptosphaeria maculans—Brassica napus Pathosystem. International Journal of Molecular Sciences. 2021; 22 (9):4812.
Chicago/Turabian StyleCunchun Yang; W. Fernando. 2021. "Analysis of the Oxidative Burst and Its Relevant Signaling Pathways in Leptosphaeria maculans—Brassica napus Pathosystem." International Journal of Molecular Sciences 22, no. 9: 4812.
Blackleg, caused by Leptosphaeria maculans, is a major disease of canola in Canada, Australia, and Europe. For effective deployment of resistant varieties and disease management, it is crucial to understand the population structure of L. maculans. In this study, we analyzed L. maculans isolates from commercial fields in western Canada from 2014 to 2016 for the presence and frequency of avirulence (Avr) genes. A total of 1,584 isolates were examined for the presence of Avr genes AvrLm1, AvrLm2, AvrLm3, AvrLm4, AvrLm6, AvrLm7, AvrLm9, AvrLepR1, AvrLepR2, and AvrLmS via a set of differential host genotypes carrying known resistance genes and a PCR assay. Several Avr genes showed a higher frequency in the pathogen population, such as AvrLm6 and AvrLm7, which were present in >90% of isolates, whereas AvrLm3, AvrLm9, and AvrLepR2 showed frequencies of <10%. A total of 189 races (different combinations of Avr genes) were detected, with Avr-2-4-6-7-S, Avr-1-4-6-7, and Avr-2-4-6-7 as the three predominant races. When the effect of crop rotation was assessed, only a 3-year rotation showed a significantly higher frequency of AvrLm2 relative to shorter rotations. This study provides the information for producers to select effective canola varieties for blackleg management and for breeders to deploy new R genes in disease resistance breeding in western Canada.
Fei Liu; Zhongwei Zou; Gary Peng; W. G. Dilantha Fernando. Leptosphaeria maculans Isolates Reveal Their Allele Frequency in Western Canada. Plant Disease 2021, 105, 1440 -1447.
AMA StyleFei Liu, Zhongwei Zou, Gary Peng, W. G. Dilantha Fernando. Leptosphaeria maculans Isolates Reveal Their Allele Frequency in Western Canada. Plant Disease. 2021; 105 (5):1440-1447.
Chicago/Turabian StyleFei Liu; Zhongwei Zou; Gary Peng; W. G. Dilantha Fernando. 2021. "Leptosphaeria maculans Isolates Reveal Their Allele Frequency in Western Canada." Plant Disease 105, no. 5: 1440-1447.
Hormone signaling plays a pivotal role in plant–microbe interactions. There are three major phytohormones in plant defense: salicylic acid (SA), jasmonic acid (JA), and ethylene (ET). The activation and trade-off of signaling between these three hormones likely determines the strength of plant defense in response to pathogens. Here, we describe the allocation of hormonal signaling in Brassica napus against the fungal pathogen Leptosphaeria maculans. Three B. napus genotypes (Westar, Surpass400, and 01-23-2-1) were inoculated with two L. maculans isolates (H75 8-1 and H77 7-2), subsequently exhibiting three levels of resistance: susceptible, intermediate, and resistant. Quantitative analyses suggest that the early activation of some SA-responsive genes, including WRKY70 and NPR1, contribute to an effective defense against L. maculans. The co-expression among factors responding to SA/ET/JA was also observed in the late stage of infection. The results of conjugated SA measurement also support that early SA activation plays a crucial role in durable resistance. Our results demonstrate the relationship between the onset patterns of certain hormone regulators and the effectiveness of the defense of B. napus against L. maculans.
Cunchun Yang; W. Fernando. Hormonal Responses to Susceptible, Intermediate, and Resistant Interactions in the Brassica napus–Leptosphaeria maculans Pathosystem. International Journal of Molecular Sciences 2021, 22, 4714 .
AMA StyleCunchun Yang, W. Fernando. Hormonal Responses to Susceptible, Intermediate, and Resistant Interactions in the Brassica napus–Leptosphaeria maculans Pathosystem. International Journal of Molecular Sciences. 2021; 22 (9):4714.
Chicago/Turabian StyleCunchun Yang; W. Fernando. 2021. "Hormonal Responses to Susceptible, Intermediate, and Resistant Interactions in the Brassica napus–Leptosphaeria maculans Pathosystem." International Journal of Molecular Sciences 22, no. 9: 4714.
Temperature is considered one of the crucial environmental elements in plant pathological interactions, and previous studies have indicated that there is a relationship between temperature change and host–pathogen interactions. The objective of this research is to investigate the link between temperature and the incompatible interactions of the host and pathogen. In this study, two Leptosphaeria maculans isolates (HCRT75 8-1 and HCRT77 7-2) and two Brassica napus genotypes (Surpass400 and 01-23-2-1) were selected. The selected B. napus genotypes displayed intermediate and resistant phenotypes. The inoculated seedlings were tested under three temperature conditions: 16 °C/10 °C, 22 °C/16 °C and 28 °C/22 °C (day/night: 16 h/8 h). Lesion measurements demonstrated that the necrotic lesions from the 28 °C/22 °C treatment were enlarged compared with the other two temperature treatments (i.e., 16 °C/10 °C and 22 °C/16 °C). The results of expression analysis indicated that the three temperature treatments displayed distinct differences in two marker genes (PATHOGENESIS–RELATED (PR) 1 and 2) for plant defense and one temperature-sensitive gene BONZAI 1 (BON1). Additionally, seven dpi at 22 °C/16 °C appeared to be the optimal pre-condition for the induction of PR1 and 2. These findings suggest that B. napus responds to temperature changes when infected with L. maculans.
Cunchun Yang; Zhongwei Zou; Wannakuwattewaduge Fernando. The Effect of Temperature on the Hypersensitive Response (HR) in the Brassica napus–Leptosphaeria maculans Pathosystem. Plants 2021, 10, 843 .
AMA StyleCunchun Yang, Zhongwei Zou, Wannakuwattewaduge Fernando. The Effect of Temperature on the Hypersensitive Response (HR) in the Brassica napus–Leptosphaeria maculans Pathosystem. Plants. 2021; 10 (5):843.
Chicago/Turabian StyleCunchun Yang; Zhongwei Zou; Wannakuwattewaduge Fernando. 2021. "The Effect of Temperature on the Hypersensitive Response (HR) in the Brassica napus–Leptosphaeria maculans Pathosystem." Plants 10, no. 5: 843.
Blackleg is a serious disease in Brassica plants, causing moderate to severe yield losses in rapeseed worldwide. Although China has not suffered from this disease yet (more aggressive Leptosphaeria maculans is not present yet), it is crucial to take provisions in breeding for disease resistance to have excellent blackleg-resistant cultivars already in the fields or in the breeding pipeline. The most efficient strategy for controlling this disease is breeding plants with identified resistance genes. We selected 135 rapeseed accessions in Sichuan, including 30 parental materials and 105 hybrids, and we determined their glucosinolate and erucic acid content and confirmed 17 double-low materials. A recently developed single-nucleotide polymorphism (SNP) marker, SNP_208, was used to genotype allelic Rlm1/rlm1 on chromosome A07, and 87 AvrLm1-resistant materials. Combined with the above-mentioned seed quality data, we identified 11 AvrLm1-resistant double-low rapeseed accessions, including nine parental materials and two hybrids. This study lays the foundation of specific R gene-oriented breeding, in the case that the aggressive Leptosphaeria maculans invades and establishes in China in the future and a robust and less labor consuming method to identify resistance in canola germplasm.
Liang Chai; Jinfang Zhang; Wannakuwattewaduge Gerard Dilantha Fernando; Haojie Li; Xiaoqin Huang; Cheng Cui; Jun Jiang; Benchuan Zheng; Yong Liu; Liangcai Jiang. Detection of Blackleg Resistance Gene Rlm1 in Double-Low Rapeseed Accessions from Sichuan Province, by Kompetitive Allele-Specific PCR. The Plant Pathology Journal 2021, 37, 194 -199.
AMA StyleLiang Chai, Jinfang Zhang, Wannakuwattewaduge Gerard Dilantha Fernando, Haojie Li, Xiaoqin Huang, Cheng Cui, Jun Jiang, Benchuan Zheng, Yong Liu, Liangcai Jiang. Detection of Blackleg Resistance Gene Rlm1 in Double-Low Rapeseed Accessions from Sichuan Province, by Kompetitive Allele-Specific PCR. The Plant Pathology Journal. 2021; 37 (2):194-199.
Chicago/Turabian StyleLiang Chai; Jinfang Zhang; Wannakuwattewaduge Gerard Dilantha Fernando; Haojie Li; Xiaoqin Huang; Cheng Cui; Jun Jiang; Benchuan Zheng; Yong Liu; Liangcai Jiang. 2021. "Detection of Blackleg Resistance Gene Rlm1 in Double-Low Rapeseed Accessions from Sichuan Province, by Kompetitive Allele-Specific PCR." The Plant Pathology Journal 37, no. 2: 194-199.
Fusarium head blight (FHB) is a major disease in wheat causing severe economic losses globally by reducing yield and contaminating grain with mycotoxins. In Canada, Fusarium graminearum is the principal etiological agent of FHB in wheat, producing mainly the trichothecene mycotoxin, deoxynivalenol (DON) and its acetyl derivatives (15-acetyl deoxynivalenol (15ADON) and 3-acetyl deoxynivalenol (3ADON)). Understanding the population biology of F. graminearum such as the genetic variability, as well as mycotoxin chemotype diversity among isolates is important in developing sustainable disease management tools. In this study, 570 F. graminearum isolates collected from commercial wheat crops in five geographic regions in three provinces in Canada in 2018 and 2019 were analyzed for population diversity and structure using 10 variable number of tandem repeats (VNTR) markers. A subset of isolates collected from the north-eastern United States was also included for comparative analysis. About 75% of the isolates collected in the Canadian provinces of Saskatchewan and Manitoba were 3ADON indicating a 6-fold increase in Saskatchewan and a 2.5-fold increase in Manitoba within the past 15 years. All isolates from Ontario and those collected from the United States were 15ADON and isolates had a similar population structure. There was high gene diversity (H = 0.803–0.893) in the F. graminearum populations in all regions. Gene flow was high between Saskatchewan and Manitoba (Nm = 4.971–21.750), indicating no genetic differentiation between these regions. In contrast, less gene flow was observed among the western provinces and Ontario (Nm = 3.829–9.756) and USA isolates ((Nm = 2.803–6.150). However, Bayesian clustering model analyses of trichothecene chemotype subpopulations divided the populations into two clusters, which was correlated with trichothecene types. Additionally, population cluster analysis revealed there was more admixture of isolates among isolates of the 3ADON chemotypes than among the 15ADON chemotype, an observation that could play a role in the increased virulence of F. graminearum. Understanding the population genetic structure and mycotoxin chemotype variations of the pathogen will assist in developing FHB resistant wheat cultivars and in mycotoxin risk assessment in Canada.
Abbot Oghenekaro; Maria Oviedo-Ludena; Mitra Serajazari; Xiben Wang; Maria Henriquez; Nancy Wenner; Gretchen Kuldau; Alireza Navabi; Hadley Kutcher; W. Fernando. Population Genetic Structure and Chemotype Diversity of Fusarium graminearum Populations from Wheat in Canada and North Eastern United States. Toxins 2021, 13, 180 .
AMA StyleAbbot Oghenekaro, Maria Oviedo-Ludena, Mitra Serajazari, Xiben Wang, Maria Henriquez, Nancy Wenner, Gretchen Kuldau, Alireza Navabi, Hadley Kutcher, W. Fernando. Population Genetic Structure and Chemotype Diversity of Fusarium graminearum Populations from Wheat in Canada and North Eastern United States. Toxins. 2021; 13 (3):180.
Chicago/Turabian StyleAbbot Oghenekaro; Maria Oviedo-Ludena; Mitra Serajazari; Xiben Wang; Maria Henriquez; Nancy Wenner; Gretchen Kuldau; Alireza Navabi; Hadley Kutcher; W. Fernando. 2021. "Population Genetic Structure and Chemotype Diversity of Fusarium graminearum Populations from Wheat in Canada and North Eastern United States." Toxins 13, no. 3: 180.
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) worldwide; however, the identification of Brassica napus VQs and their functions in response to blackleg disease have not yet been reported. In this study, we conducted a genome-wide identification and characterization of the VQ gene family in Brassica napus, including chromosome location, phylogenetic relations, gene structure, motif domain, synteny analysis, and cis-elements categorization of their promoter regions. To understand Brassica napus VQ gene function in response to blackleg disease, we overexpressed BnVQ7 (BnaA01g36880D, also known as the mitogen-activated protein kinase 4 substrate 1 [MKS1] gene) in a blackleg-susceptible canola variety, Westar. Overexpression of BnMKS1 in canola did not improve its resistance to blackleg disease at the seedling stage; 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 salicylic acid- and jasmonic acid-mediated signaling pathways were both involved in the defense responses. Together, these results suggest that BnMKS1 might play an important role in defense against L. maculans. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
Zhongwei Zou; Fei Liu; Shuanglong Huang; Dilantha Gerard Fernando. Genome-Wide Identification and Analysis of the Valine-Glutamine Motif-Containing Gene Family in Brassica napus and Functional Characterization of BnMKS1 in Response to Leptosphaeria maculans. Phytopathology® 2021, 111, 281 -292.
AMA StyleZhongwei Zou, Fei Liu, Shuanglong Huang, Dilantha Gerard Fernando. Genome-Wide Identification and Analysis of the Valine-Glutamine Motif-Containing Gene Family in Brassica napus and Functional Characterization of BnMKS1 in Response to Leptosphaeria maculans. Phytopathology®. 2021; 111 (2):281-292.
Chicago/Turabian StyleZhongwei Zou; Fei Liu; Shuanglong Huang; Dilantha Gerard Fernando. 2021. "Genome-Wide Identification and Analysis of the Valine-Glutamine Motif-Containing Gene Family in Brassica napus and Functional Characterization of BnMKS1 in Response to Leptosphaeria maculans." Phytopathology® 111, no. 2: 281-292.
Fusarium head blight (FHB) is a major fungal disease that contributes to severe economic losses for wheat and barley production in Canada and other parts of the world. Rapid developments in molecular biology over the past three decades have improved the ability to devise predictive management tools to combat the effects of the disease. Important aspects of Fusarium species in terms of the epidemiology associated with FHB in wheat and barley have been reported. The role of mycotoxin production in the epidemiology of the disease is beginning to receive much needed research attention. Evolutionary factors and the use of fungicides have resulted in more virulent forms of the FHB pathogens. Advances in next-generation sequencing technologies, including whole genome sequencing (WGS), genome-wide association studies (GWAS), genotyping by sequencing (GBS) and RNA sequencing (RNA-Seq) have facilitated the selection of resistant breeding lines through marker-assisted selection. Many quantitative trait loci (QTL) associated with moderate disease resistance have been identified in wheat and barley. Changes in weather conditions play an important role in FHB epidemics and dissemination, thus a systematic and long-term research approach is needed to provide effective forecasting and risk assessment models. This review discusses the history and epidemiology of FHB pathogens in wheat and barley at the global level, as well as potential plant defense mechanisms, the recent progress made in resistance breeding, and modern tools utilized in disease prediction. It also provides future directions for improving the management of the disease with these two important cereals.
W.G. Dilantha Fernando; Abbot O. Oghenekaro; James R. Tucker; Ana Badea. Building on a foundation: advances in epidemiology, resistance breeding, and forecasting research for reducing the impact of fusarium head blight in wheat and barley. Canadian Journal of Plant Pathology 2021, 43, 495 -526.
AMA StyleW.G. Dilantha Fernando, Abbot O. Oghenekaro, James R. Tucker, Ana Badea. Building on a foundation: advances in epidemiology, resistance breeding, and forecasting research for reducing the impact of fusarium head blight in wheat and barley. Canadian Journal of Plant Pathology. 2021; 43 (4):495-526.
Chicago/Turabian StyleW.G. Dilantha Fernando; Abbot O. Oghenekaro; James R. Tucker; Ana Badea. 2021. "Building on a foundation: advances in epidemiology, resistance breeding, and forecasting research for reducing the impact of fusarium head blight in wheat and barley." Canadian Journal of Plant Pathology 43, no. 4: 495-526.
A fundamental process culminating in the mechanisms of plant-pathogen interactions is the regulation of trophic divergence into biotrophic, hemibiotrophic, and necrotrophic interactions. Plant hormones, of almost all types, play significant roles in this regulatory apparatus. In plant-pathogen interactions, two classical mechanisms underlying hormone-dependent trophic divergence are long recognized. While salicylic acid dominates in the execution of host defense response against biotrophic and early-stage hemibiotrophic pathogens, jasmonic acid, and ethylene are key players facilitating host defense response against necrotrophic and later-stage hemibiotrophic pathogens. Evidence increasingly suggests that trophic divergence appears to be modulated by more complex signaling networks. Acting antagonistically or agonistically, other hormones such as auxins, cytokinins, abscisic acid, gibberellins, brassinosteroids, and strigolactones, as well as nitric oxide, are emerging candidates in the regulation of trophic divergence. In this review, the latest advances in the dynamic regulation of trophic divergence are summarized, emphasizing common and contrasting hormonal and nitric oxide signaling strategies deployed in plant-pathogen interactions.
Shuanglong Huang; Xuehua Zhang; W. G. Dilantha Fernando. Directing Trophic Divergence in Plant-Pathogen Interactions: Antagonistic Phytohormones With NO Doubt? Frontiers in Plant Science 2020, 11, 1 .
AMA StyleShuanglong Huang, Xuehua Zhang, W. G. Dilantha Fernando. Directing Trophic Divergence in Plant-Pathogen Interactions: Antagonistic Phytohormones With NO Doubt? Frontiers in Plant Science. 2020; 11 ():1.
Chicago/Turabian StyleShuanglong Huang; Xuehua Zhang; W. G. Dilantha Fernando. 2020. "Directing Trophic Divergence in Plant-Pathogen Interactions: Antagonistic Phytohormones With NO Doubt?" Frontiers in Plant Science 11, no. : 1.
Canola (Brassica napus) is the major oilseed crop in Canada. Blackleg, (Leptosphaeria maculans) causes yield losses annually, with a larger impact in the last two decades caused by breakdown of resistance in growers’ fields. A 4‐year small plot field study from 2014 to 2017 in Manitoba investigated the impact of the B. napus–L. maculans interaction on the emergence of virulent isolates towards specific R genes. Double haploid B. napus ‘Topas’ introgression lines carrying single R genes were used, with a 2‐year canola–wheat rotation. Blackleg incidence was reduced by 40% in 2017 compared to 2014 for all R genes tested except Rlm4. In 2017, disease severity was reduced between 21% and 52% compared to 2014 for all R genes tested except Rlm2. There was a significant shift from AvrLm2 and AvrLm4 to virulent alleles avrLm2 and avrLm4 respectively, which led to the gain of virulence toward Rlm2 and Rlm4 Topas introgression lines within a year. Sequencing of the AvrLm2 gene of isolates from 2014 and 2015 revealed a shift of AvrLm2 to avrLm2 allele due to accumulation of point mutations. Masking of AvrLm3 phenotype by the presence of the AvrLm4‐7 allele was also confirmed by analysing phenotypes and genotypes of the isolates collected from 2014 to 2017. Based on these and previous findings, we demonstrate the need for an epidemiological model that takes into account complex molecular mechanisms allowing plant breeders to select appropriate R genes, including balanced cultivar rotation strategies to maintain blackleg resistance in the Canadian Prairies.
M. Harunur Rashid; Sakaria Liban; Xuehua Zhang; Paula Parks; Hossein Borhan; W. G. Dilantha Fernando. Impact of Brassica napus–Leptosphaeria maculans interaction on the emergence of virulent isolates of L. maculans , causal agent of blackleg disease in canola. Plant Pathology 2020, 70, 459 -474.
AMA StyleM. Harunur Rashid, Sakaria Liban, Xuehua Zhang, Paula Parks, Hossein Borhan, W. G. Dilantha Fernando. Impact of Brassica napus–Leptosphaeria maculans interaction on the emergence of virulent isolates of L. maculans , causal agent of blackleg disease in canola. Plant Pathology. 2020; 70 (2):459-474.
Chicago/Turabian StyleM. Harunur Rashid; Sakaria Liban; Xuehua Zhang; Paula Parks; Hossein Borhan; W. G. Dilantha Fernando. 2020. "Impact of Brassica napus–Leptosphaeria maculans interaction on the emergence of virulent isolates of L. maculans , causal agent of blackleg disease in canola." Plant Pathology 70, no. 2: 459-474.
Leptosphaeria maculans, the causal agent of blackleg disease, interacts with Brassica napus (oilseed rape, canola) in a gene-for-gene manner. The avirulence genes AvrLmS and AvrLep2 were described to be perceived by the resistance genes RlmS and LepR2, respectively, present in the cultivar Surpass 400. Here we report cloning of AvrLmS and AvrLep2 using two independent methods. AvrLmS was cloned using combined in vitro crossing between avirulent and virulent isolates with sequencing of DNA bulks from avirulent or virulent progeny (Bulked-Segregant-Sequencing) to rapidly identify one candidate avirulence gene present in the effector repertoire of L. maculans. AvrLep2 was cloned using a bi-parental cross of avirulent and virulent L. maculans isolates and a classical map-based cloning approach. Taking these two approaches independently, we found that AvrLmS and AvrLep2 are the same gene. Complementation of virulent isolates with this gene confirmed its role in inducing resistance on Surpass 400 and Topas-LepR2. The gene renamed AvrLmS-Lep2 encodes for a small cysteine-rich protein of unknown function with an N-terminal secretory signal peptide, which are common features of the majority of effectors from extracellular fungal plant pathogens. The AvrLmS-Lep2 / LepR2 interaction phenotype was found to vary from a typical hypersensitive response to intermediate resistance sometimes at the edge of, or evolving toward, susceptibility depending on the inoculation conditions. AvrLmS-Lep2 was nevertheless sufficient to significantly reduce the stem lesion size on plant genotypes with LepR2, indicating the potential efficiency of this resistance to control the disease in the field.
Ting Xiang Neik; Kaveh Ghanbarnia; Benedicte Ollivier; Armin Scheben; Anita Severn-Ellis; Nicholas J Larkan; Parham Haddadi; Dilantha Gw Fernando; Thierry Rouxel; Jacqueline Batley; Hossein M Borhan; Marie-Helene Balesdent. Two independent approaches converge to the cloning of a new Leptosphaeria maculans avirulence effector gene, AvrLmS-Lep2. 2020, 1 .
AMA StyleTing Xiang Neik, Kaveh Ghanbarnia, Benedicte Ollivier, Armin Scheben, Anita Severn-Ellis, Nicholas J Larkan, Parham Haddadi, Dilantha Gw Fernando, Thierry Rouxel, Jacqueline Batley, Hossein M Borhan, Marie-Helene Balesdent. Two independent approaches converge to the cloning of a new Leptosphaeria maculans avirulence effector gene, AvrLmS-Lep2. . 2020; ():1.
Chicago/Turabian StyleTing Xiang Neik; Kaveh Ghanbarnia; Benedicte Ollivier; Armin Scheben; Anita Severn-Ellis; Nicholas J Larkan; Parham Haddadi; Dilantha Gw Fernando; Thierry Rouxel; Jacqueline Batley; Hossein M Borhan; Marie-Helene Balesdent. 2020. "Two independent approaches converge to the cloning of a new Leptosphaeria maculans avirulence effector gene, AvrLmS-Lep2." , no. : 1.
Blackleg, which is caused by the fungus Leptosphaeria maculans (L. maculans), is a major disease of canola in western Canada and worldwide. Long-term use of one source of resistance could cause the breakdown of its effectiveness. Therefore, appropriate use of R genes is very important, and knowledge about the distribution of avirulence genes is a prerequisite for effectively deploying resistance. Of the 14 avirulence genes identified in L. maculans, AvrLm5 and AvrLm9 were recognized as the two alleles of the same gene based on two single nucleotide polymorphisms, C85T and G164A/C. In this study, a specific marker was developed to identify AvrLm5 and AvrLm9 based on two single nucleotide polymorphisms, C85T and G164A/C, which are responsible for the function of AvrLm9. The specific marker can be used to discriminate the AvrLm9 from avrLm9 accurately in L. maculans isolates, which is consistent with inoculation tests in isolates without AvrLm4-7. This specific marker was used to screen 1229 isolates collected from fields in the years 2014 through 2016 in Manitoba. From 68 to 84% of the isolates were found to contain the AvrLm9 allele; while 4–7% of them were avirulent on the variety Goéland with Rlm9 loci. Furthermore, no isolates having both AvrLm9 and AvrLm7 were detected using a cotyledon test, while 67% to 84% of isolates contained both avirulence genes via PCR detection, implying suppression of AvrLm9 by AvrLm7. In addition, avirulence gene profiles of the other 10 avirulence alleles were examined with the 1229 isolates using cotyledon tests or PCR amplifications. Taken together, this research enables the fast identification of AvrLm5/9, provides the Avr genes’ landscape of western Canada and elaborates the relationship between AvrLm9 and AvrLm7 using isolates from grower fields.
Fei Liu; Zhongwei Zou; Shuanglong Huang; Paula Parks; W. G. Dilantha Fernando. Development of a specific marker for detection of a functional AvrLm9 allele and validating the interaction between AvrLm7 and AvrLm9 in Leptosphaeria maculans. Molecular Biology Reports 2020, 47, 7115 -7123.
AMA StyleFei Liu, Zhongwei Zou, Shuanglong Huang, Paula Parks, W. G. Dilantha Fernando. Development of a specific marker for detection of a functional AvrLm9 allele and validating the interaction between AvrLm7 and AvrLm9 in Leptosphaeria maculans. Molecular Biology Reports. 2020; 47 (9):7115-7123.
Chicago/Turabian StyleFei Liu; Zhongwei Zou; Shuanglong Huang; Paula Parks; W. G. Dilantha Fernando. 2020. "Development of a specific marker for detection of a functional AvrLm9 allele and validating the interaction between AvrLm7 and AvrLm9 in Leptosphaeria maculans." Molecular Biology Reports 47, no. 9: 7115-7123.
Blackleg, caused by the fungal pathogen Leptosphaeria maculans, is the most important disease affecting canola (Brassica napus) crops worldwide. We employed the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) system to generate the mutant isolate umavr7 from a point mutation of the AvrLm7 coding region in a L. maculans isolate (UMAvr7). Reverse transcription PCR and transcriptome data confirmed that the AvrLm7 gene was knocked out in the mutant isolate. Pathogenicity tests indicated that umavr7 can cause large lesions on a set of Brassica differential genotypes that express different resistance (R) genes. Comparative pathogenicity tests between UMAvr7 (wild type) and umavr7 on the corresponding B. napus genotype 01-23-2-1 (with Rlm7) showed that umavr7 is a mutant isolate, producing large gray/green lesions on cotyledons. The pathogenicity of the mutant isolate was shifted from avirulent to virulent on the B. napus Rlm7 genotype. Therefore, this mutant is virulence on the identified resistant genes to blackleg disease in B. napus genotypes. Superoxide accumulated differently in cotyledons in response to infection with UMAvr7 and umavr7, especially in resistant B. napus genotype 01-23-2-1. Resistance/susceptibility was further evaluated on 123 B. napus genotypes with the mutant isolate, umavr7. Only 6 of the 123 genotypes showed resistance to umavr7. The identification of these six resistant B. napus genotypes will lead to further studies on the development of blackleg disease resistance through breeding and the identification of novel R genes.
Zhongwei Zou; Fei Liu; Carrie Selin; W. G. Dilantha Fernando. Generation and Characterization of a Virulent Leptosphaeria maculans Isolate Carrying a Mutated AvrLm7 Gene Using the CRISPR/Cas9 System. Frontiers in Microbiology 2020, 11, 1969 .
AMA StyleZhongwei Zou, Fei Liu, Carrie Selin, W. G. Dilantha Fernando. Generation and Characterization of a Virulent Leptosphaeria maculans Isolate Carrying a Mutated AvrLm7 Gene Using the CRISPR/Cas9 System. Frontiers in Microbiology. 2020; 11 ():1969.
Chicago/Turabian StyleZhongwei Zou; Fei Liu; Carrie Selin; W. G. Dilantha Fernando. 2020. "Generation and Characterization of a Virulent Leptosphaeria maculans Isolate Carrying a Mutated AvrLm7 Gene Using the CRISPR/Cas9 System." Frontiers in Microbiology 11, no. : 1969.
Plant growth promoting bacteria (PGPB) are a growing subset of agricultural adjuncts which can be used to increase crop yield and plant productivity. Although substantial research has been conducted on the metabolites and active molecules secreted by PGPBs, relatively little is known about their effects on the global transcriptome of the host plant. The present study was carried out to investigate changes in the gene expression landscape of early vegetative Brassica napus following treatment with Pseudomonas chlororaphis PA23. This PGPB was isolated from the soybean rhizosphere and has been extensively studied as a biocontrol agent. However, little is known about its effects on plant growth and development. Using a combination of RNA-sequencing and physiological analyses, we identified increased abundance of mRNA transcripts associated with photosynthesis and phytohormone response. Phenotypically we observed increased photosynthetic rates and larger root and shoot systems in B. napus following P. chlororaphis PA23 treatment. Lastly, we identified auxin production by P. chlororaphis PA23 which likely contributes to changes in gene expression and the observed phenotypic differences in root and shoot structures. Together, the results of our study suggest that PA23 is a potent plant growth promoting agent with the potential for field applications as an agricultural adjunct.
Mark F. Belmonte; Teresa R De Kievit; Joey C Wan; Ayo Bolaji; Emma Gray; Michael G Becker; Philip L Walker; Wg Dilantha Fernando. Global RNA sequencing reveals enhanced photosynthetic activity and auxin response in Brassica napus treated with Pseudomonas chlororaphis PA23. 2020, 1 .
AMA StyleMark F. Belmonte, Teresa R De Kievit, Joey C Wan, Ayo Bolaji, Emma Gray, Michael G Becker, Philip L Walker, Wg Dilantha Fernando. Global RNA sequencing reveals enhanced photosynthetic activity and auxin response in Brassica napus treated with Pseudomonas chlororaphis PA23. . 2020; ():1.
Chicago/Turabian StyleMark F. Belmonte; Teresa R De Kievit; Joey C Wan; Ayo Bolaji; Emma Gray; Michael G Becker; Philip L Walker; Wg Dilantha Fernando. 2020. "Global RNA sequencing reveals enhanced photosynthetic activity and auxin response in Brassica napus treated with Pseudomonas chlororaphis PA23." , no. : 1.
The fungal pathogen Leptosphaeria maculans (Lm). causes blackleg disease on canola/rapeseed in many parts of the world. It is important to use resistant cultivars to manage the disease and minimize yield losses. In this study, twenty-two Lm isolates were used to identify resistance genes in a collection of 243 canola/rapeseed (Brassica napus L.) accessions from Canada and China. These Lm isolates carry different compliments of avirulence genes, and the investigation was based on a genome-wide association study (GWAS) and genotype-by-sequencing (GBS). Using the CROP-SNP pipeline, a total of 81,471 variants, including 78,632 SNPs and 2839 InDels, were identified. The GWAS was performed using TASSEL 5.0 with GLM + Q model. Thirty-two and 13 SNPs were identified from the Canadian and Chinese accessions, respectively, tightly associated with blackleg resistance with P values < 1 × 10− 4. These SNP loci were distributed on chromosomes A03, A05, A08, A09, C01, C04, C05, and C07, with the majority of them on A08 followed by A09 and A03. The significant SNPs identified on A08 were all located in a 2010-kb region and associated with resistance to 12 of the 22 Lm isolates. Furthermore, 25 resistance gene analogues (RGAs) were identified in these regions, including two nucleotide binding site (NBS) domain proteins, fourteen RLKs, three RLPs and six TM-CCs. These RGAs can be the potential candidate genes for blackleg resistance. This study provides insights into potentially new genomic regions for discovery of additional blackleg resistance genes. The identified regions associated with blackleg resistance in the germplasm collection may also contribute directly to the development of canola varieties with novel resistance genes against blackleg of canola.
Fuyou Fu; Xuehua Zhang; Fei Liu; Gary Peng; Fengqun Yu; Dilantha Fernando. Identification of resistance loci in Chinese and Canadian canola/rapeseed varieties against Leptosphaeria maculans based on genome-wide association studies. BMC Genomics 2020, 21, 1 -11.
AMA StyleFuyou Fu, Xuehua Zhang, Fei Liu, Gary Peng, Fengqun Yu, Dilantha Fernando. Identification of resistance loci in Chinese and Canadian canola/rapeseed varieties against Leptosphaeria maculans based on genome-wide association studies. BMC Genomics. 2020; 21 (1):1-11.
Chicago/Turabian StyleFuyou Fu; Xuehua Zhang; Fei Liu; Gary Peng; Fengqun Yu; Dilantha Fernando. 2020. "Identification of resistance loci in Chinese and Canadian canola/rapeseed varieties against Leptosphaeria maculans based on genome-wide association studies." BMC Genomics 21, no. 1: 1-11.
Verticillium stripe in canola (Brassica napus L.) caused by Verticillium longisporum was first reported in Manitoba in 2014. In this study, Brassica crops including canola, mustard (Brassica juncea) and radish (Raphanus sativus) with visible symptoms of Verticillium stripe were collected from Portage La Prairie, Manitoba, and the pathogens were isolated. Isolates from canola and radish were identified to V. longisporum, which produced longer conidia (7.92–12.00 µm) than Verticillium dahliae (4.32–7.04 µm). An isolate derived from mustard was characterized as V. dahliae. Molecular diagnostics with 18S rDNA, 5.8S rDNA and mating-type marker primers were used to confirm the identification of Verticillium isolates. PCR-RFLP of the mitochondrial small subunit rDNA and the cytochrome b gene were also employed to distinguish V. longisporum isolates from V. dahliae. The multi-gene characterization approach allowed for lineage determination, and V. longisporum isolates from canola and radish were in the A1/D1 group. Isolates of Verticillium longisporum from canola inoculated onto the canola cultivar ‘Westar’ caused symptoms of stem striping, stunting and short plants. Re-isolated fungal strains from infected stems were again inoculated onto canola plants, in order to confirm that V. longisporum was the causal agent of Verticillium stripe disease in the pathogenicity test.
Zhongwei Zou; Vikram Bisht; W. G. Dilantha Fernando. Identification and Characterization of Verticillium longisporum Lineage A1/D1 from Brassica Crops in Manitoba, Canada. International Journal of Molecular Sciences 2020, 21, 3499 .
AMA StyleZhongwei Zou, Vikram Bisht, W. G. Dilantha Fernando. Identification and Characterization of Verticillium longisporum Lineage A1/D1 from Brassica Crops in Manitoba, Canada. International Journal of Molecular Sciences. 2020; 21 (10):3499.
Chicago/Turabian StyleZhongwei Zou; Vikram Bisht; W. G. Dilantha Fernando. 2020. "Identification and Characterization of Verticillium longisporum Lineage A1/D1 from Brassica Crops in Manitoba, Canada." International Journal of Molecular Sciences 21, no. 10: 3499.
Leptosphaeria maculans is the causal agent of blackleg disease on Brassica napus. Determining the underlying functions of genes required for pathogenesis is essential for understanding the infection process. A chitin-binding protein (LmCBP1) was discovered as a pathogenicity factor for the infection of B. napus by L. maculans through gene knockout using the CRISPR-Cas9 system. Chitin-binding activity was demonstrated through a chitin-protein binding assay. A secreted signal peptide was detected using a yeast secreted-signal peptide trap assay. An increased expression level during the infection stage was also observed, suggesting that LmCBP1 is a secreted protein. The knockout mutants showed decreased infection on B. napus, with reduced pathogenicity on ten cultivars with/without diverse R genes. The mutants were more sensitive to H2O2 compared to wild type L. maculans isolate JN3. This study provides evidence of the virulence of a novel chitin-binding protein LmCBP1 on B. napus through mutants created via the CRISPR-Cas9 system.
Fei Liu; Carrie Selin; Zhongwei Zou; W.G. Dilantha Fernando. LmCBP1, a secreted chitin-binding protein, is required for the pathogenicity of Leptosphaeria maculans on Brassica napus. Fungal Genetics and Biology 2019, 136, 103320 .
AMA StyleFei Liu, Carrie Selin, Zhongwei Zou, W.G. Dilantha Fernando. LmCBP1, a secreted chitin-binding protein, is required for the pathogenicity of Leptosphaeria maculans on Brassica napus. Fungal Genetics and Biology. 2019; 136 ():103320.
Chicago/Turabian StyleFei Liu; Carrie Selin; Zhongwei Zou; W.G. Dilantha Fernando. 2019. "LmCBP1, a secreted chitin-binding protein, is required for the pathogenicity of Leptosphaeria maculans on Brassica napus." Fungal Genetics and Biology 136, no. : 103320.
Pseudomonas chlororaphis strain PA23 is a biocontrol agent capable of protecting canola from stem rot disease caused by the fungal pathogen Sclerotinia sclerotiorum. PA23 produces several of inhibitory compounds that are under control of a complex regulatory network. Included in this cascade is the PhzRI quorum sensing (QS) system, which plays an essential role in PA23 biocontrol. The focus of the current study was to employ RNA sequencing to explore the spectrum of PA23 genes under QS control. Transcriptomic profiling revealed 545 differentially expressed genes (365 downregulated; 180 upregulated) in the phzR mutant and 534 genes (382 downregulated; 152 upregulated) in the AHL-deficient PA23-6863. In both strains, decreased expression of phenazine, pyrrolnitrin, and exoprotease biosynthetic genes was observed. We have previously reported that QS activates expression of these genes and their encoded products. In addition, elevated siderophore and decreased chitinase gene expression was observed in the QS-deficient stains, which was confirmed by phenotypic analysis. Inspection of the promoter regions revealed the presence of “phz-box” sequences in only 58 of the 807 differentially expressed genes, suggesting that much of the QS regulon is indirectly regulated. Consistent with this notion, 41 transcriptional regulators displayed altered expression in one or both of the QS-deficient strains. Collectively, our findings indicate that QS governs expression of approximately 13% of the PA23 genome affecting diverse functions ranging from secondary metabolite production to general metabolism. To the best of our knowledge, this represents the first global transcriptomic analysis of the QS regulon of a biocontrol pseudomonad.
Nidhi Shah; April Gislason; Michael Becker; Mark F. Belmonte; W.G. Dilantha Fernando; Teresa R. De Kievit. Investigation of the quorum-sensing regulon of the biocontrol bacterium Pseudomonas chlororaphis strain PA23. 2019, 854596 .
AMA StyleNidhi Shah, April Gislason, Michael Becker, Mark F. Belmonte, W.G. Dilantha Fernando, Teresa R. De Kievit. Investigation of the quorum-sensing regulon of the biocontrol bacterium Pseudomonas chlororaphis strain PA23. . 2019; ():854596.
Chicago/Turabian StyleNidhi Shah; April Gislason; Michael Becker; Mark F. Belmonte; W.G. Dilantha Fernando; Teresa R. De Kievit. 2019. "Investigation of the quorum-sensing regulon of the biocontrol bacterium Pseudomonas chlororaphis strain PA23." , no. : 854596.