scholarly journals Characterization of the Race Structure of Leptosphaeria maculans Causing Blackleg of Winter Canola in Oklahoma and Kansas

Plant Disease ◽  
2019 ◽  
Vol 103 (9) ◽  
pp. 2353-2358 ◽  
Author(s):  
Claudia Diaz ◽  
Felipe Cevallos ◽  
John Damicone
Keyword(s):  
Cultural Practices ◽  
Quantitative Resistance ◽  
Genetic Resistance ◽  
Leptosphaeria Maculans ◽  
Pcr Amplification ◽  
Avirulence Genes ◽  
Winter Canola ◽  
Differential Cultivars ◽  
Species Specific

Blackleg, caused by the fungus Leptosphaeria maculans, is a widespread disease of winter canola (Brassica napus) in Oklahoma and Kansas. Deployment of genetic resistance is the primary strategy for managing blackleg. Resistance genes (Rlm) in canola interact with avirulence genes in the fungus (AvrLm) in a gene-for-gene manner. Little is known about the diversity and frequency of avirulence genes and the race structure in the region. Isolates of Leptosphaeria spp. were collected from diseased leaves in nine counties in Oklahoma and one county in Kansas from 2009 to 2013. Based on pathogenicity and PCR amplification of mating type and species-specific internal transcribed spacer loci, most isolates (n = 90) were L. maculans. The presence of avirulence genes was evaluated using phenotypic interactions on cotyledons of differential cultivars with Rlm1, Rlm2, Rlm3, and Rlm4 and amplification of AvrLm1, AvrLm4-7, and AvrLm6 by PCR. The avirulence alleles AvrLm6 and AvrLm7 were present in the entire L. maculans population. AvrLm1 was found in 34% of the population, AvrLm2 in 4%, and AvrLm4 in only 1%. A total of five races, defined as combinations of avirulence alleles, were identified that included AvrLm1-2-6-7, AvrLm2-6-7, AvrLm4-6-7, AvrLm1-6-7, and AvrLm6-7. Races virulent on the most Rlm genes, AvrLm1-6-7 at 32% and AvrLm6-7 at 62%, were predominant. Defining the avirulence allele frequency and race structure of L. maculans should be useful for the identification and development of resistant cultivars and hybrids for blackleg management in the region. The results suggest that Rlm6 and Rlm7 would be effective, although their deployment should be integrated with quantitative resistance and cultural practices, such as crop rotation, that limit selection pressure on Rlm genes.

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

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

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

scholarly journals Identification of Genome-Wide DNA Variants and SNP Haplotypes Associated with Avirulence Genes of Leptosphaeria Maculans in Western Canada

2020 ◽  
Author(s):  
Qilin Chen ◽  
Gary Peng ◽  
Randy Kutcher ◽  
Fengqun Yu
Keyword(s):  
Genetic Resistance ◽  
Leptosphaeria Maculans ◽  
Block Size ◽  
Integrated Approach ◽  
Western Canada ◽  
Avirulence Genes ◽  
Illumina Platform ◽  
Genome Wide ◽  
Dna Variants ◽  
Serious Disease

Abstract BackgroundBlackleg, caused by Leptosphaeria maculans, is a serious disease of canola/ oilseed rape in many parts of the world. An integrated approach is needed to control the disease, with genetic resistance as a key component of the management strategy. Towards this goal, a reliable approach for L. maculans race structure assessment becomes essential to gain understanding of the frequency of avirulence genes and race groups of the pathogen, and provide guidance for deployment of resistant canola cultivars.ResultsA total of 162 representative isolates collected in western Canada were selected for genome re-sequencing with an Illumina platform. Assembly of the short reads against the reference genome of L. maculans 'brassicae' isolate v23.1.3 led to the discovery of 21,016 DNA variants (SNPs and InDels), 93% SNPs and 7% InDels, with a transition/transversion (Ts/Tv) ratio of 3.1 genome wide. InDels occurred mainly in GC-blocks and the Ts/Tv ratio of SNPs in AT-blocks was > 2 times higher than that in GC-blocks. The number of variants were positively correlated with supercontig size, GC-block size and gene numbers. DNA variants in most avirulence genes were SNPs, except a deletion in AvrLm1. The number of SNPs varied from 1–2 in AvrLm2, AvrLmJ1-5-9, AvrLm6, AvrLm10A, AvrLm10B and AvrLm11, 8 in AvrLm3 and 38 in AvrLm4-7. This study is the first report of triallelic SNPs in AvrLm2 and AvrLm4-7, and premature STOP codons in AvrLm4-7. Nine SNP haplotypes were identified in AvrLm4-7, however, only 2 ~ 3 haplotypes occurred in other avirulence genes, and in total 47 haplotype groups were identified from the isolates. The 47 SNP haplotype groups were translated into 44 protein haplotype groups and then isolates of L. macualns collected in western Canada were classified into10 races.ConclusionIn this study, we document the shortcoming of inferring races from SNP genotyping, and propose the use of SNP haplotyping for more reliable and informative analysis of L. maculans race structure.

scholarly journals Characterization of Colletotrichum acutatum Causing Anthracnose of Anemone (Anemone coronaria L.)

2000 ◽  
Vol 66 (12) ◽  
pp. 5267-5272 ◽  
Author(s):  
Stanley Freeman ◽  
Ezra Shabi ◽  
Talma Katan
Keyword(s):  
Western Europe ◽  
Pcr Amplification ◽  
Vegetative Compatibility ◽  
Colletotrichum Acutatum ◽  
Vegetative Compatibility Groups ◽  
The Third ◽  
Artificial Inoculations ◽  
Species Specific ◽  
Arbitrarily Primed Pcr

ABSTRACT Anthracnose, or leaf-curl disease of anemone, caused byColletotrichum sp., has been reported to occur in Australia, western Europe, and Japan. Symptoms include tissue necrosis, corm rot, leaf crinkles, and characteristic spiral twisting of floral peduncles. Three epidemics of the disease have been recorded in Israel: in 1978, in 1990 to 1993, and in 1996 to 1998. We characterized 92Colletotrichum isolates associated with anthracnose of anemone (Anemone coronaria L.) for vegetative compatibility (72 isolates) and for molecular genotype (92 isolates) and virulence (4 isolates). Eighty-six of the isolates represented the three epidemics in Israel, one isolate was from Australia, and five isolates originated from western Europe. We divided these isolates into three vegetative-compatibility groups (VCGs). One VCG (ANE-A) included all 10 isolates from the first and second epidemics, and 13 of 62 examined isolates from the third epidemic in Israel, along with the isolate from Australia and 4 of 5 isolates from Europe. Another VCG (ANE-F) included most of the examined isolates (49 of the 62) from the third epidemic, as well as Colletotrichum acutatum from strawberry, in Israel. Based on PCR amplification with species-specific primers, all of the anemone isolates were identified as C. acutatum. Anemone and strawberry isolates of the two VCGs were genotypically similar and indistinguishable when compared by arbitrarily primed PCR of genomic DNA. Only isolate NL-12 from The Netherlands, confirmed as C. acutatum but not compatible with either VCG, had a distinct genotype; this isolate represents a third VCG of C. acutatum. Isolates from anemone and strawberry could infect both plant species in artificial inoculations. VCG ANE-F was recovered from natural infections of both anemone and strawberry, but VCG ANE-A was recovered only from anemone. This study of C. acutatum from anemone illustrates the potential of VCG analysis to reveal distinct subspecific groups within a pathogen population which appears to be genotypically homogeneous by molecular assays.

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

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

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

Trypanosoma vivax: Characterization of the Spliced-Leader Gene of a Brazilian Stock and Species-Specific Detection by PCR Amplification of an Intergenic Spacer Sequence

2001 ◽  
Vol 99 (1) ◽  
pp. 37-48 ◽  
Author(s):  
Rogéria M Ventura ◽  
Fernando Paiva ◽  
Roberto A.M.S Silva ◽  
Gentilda F Takeda ◽  
Gregory A Buck ◽  
...  
Keyword(s):  
Pcr Amplification ◽  
Intergenic Spacer ◽  
Trypanosoma Vivax ◽  
Specific Detection ◽  
Spliced Leader ◽  
Species Specific

scholarly journals Listeriosis in a peri-urban area: Cultural and molecular characterization of Listeria monocytogenes isolated from encephalitic goats

2020 ◽  
Vol 13 (9) ◽  
pp. 1743-1749
Author(s):  
Nagendra Nath Barman ◽  
Anjan Jyoti Nath ◽  
Sharmita Doley ◽  
Shameem Ara Begum ◽  
Parikshit Kakati ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
16S Rrna ◽  
Molecular Characterization ◽  
Early Stage ◽  
Meat Products ◽  
Pcr Amplification ◽  
High Dose ◽  
Molecular Tests ◽  
Species Specific

Background and Aim: Listeriosis in food animals bears a significant threat to human health. Detailed investigations into the cause facilitate proper management of the disease. This study reports the cultural, pathological, and molecular characterization of Listeria monocytogenes isolated from encephalitic goats from peri-urban Guwahati, Assam. Materials and Methods: Out of nine suspected samples, five positive isolates of L. monocytogenes were subjected to bacteriological, biochemical, and molecular tests. The genus and species-specific L. monocytogenes 16S rRNA and prs genes were amplified by polymerase chain reaction (PCR) to yield 1200 and 370 bp sized products, respectively. The encephalitic form of the disease was characterized by circling movement, high fever, and terminal recumbence. Results: All the five isolates were confirmed to be L. monocytogenes based on PCR amplification of genus and species-specific 16S rRNA and prs gene products. The isolates were sensitive to ciprofloxacin, oxytetracycline (OTC), and norfloxacin, but resistant to doxycycline and erythromycin. A high dose of OTC was used in a goat at the early stage of clinical symptom and the animal recovered clinically. Conclusion: Listeriosis in goats could pose a significant public health threat as the meat (occasionally milk) or meat products from goats are widely consumed by the people of Assam. Understanding the molecular epidemiological aspects of L. monocytogenes infections of food animal species should, therefore, be the priority in this part of the country.

Characterization of a cDNA for Rhesus Monkey Protein C Inhibitor – Evidence for N-Terminal Involvement in Heparin Stimulation

1995 ◽  
Vol 74 (04) ◽  
pp. 1079-1087 ◽  
Author(s):  
Klaus-P Radtke ◽  
José A Fernández ◽  
Bruno O Villoutreix ◽  
Judith S Greengard ◽  
John H Griffin
Keyword(s):  
Rhesus Monkey ◽  
Protein C ◽  
Activated Protein C ◽  
Pcr Amplification ◽  
Amino Acid Sequences ◽  
Heparin Binding ◽  
Reactive Center ◽  
Protein C Inhibitor ◽  
Polymerase Chain

SummarycDNAs for protein C inhibitor (PCI) were cloned from human and rhesus monkey 1 liver RNAs by reverse transcription and polymerase chain reaction (PCR) amplification. Sequencing showed that rhesus monkey and human PCI cDNAs were 93% identical. Predicted amino acid sequences differed at 26 of 387 residues. Pour of these differences (T352M, N359S, R362K, L3631) were in the reactive center loop that is important for inhibitory specificity, and two were in the N-terminal helix (M8T, E13K) that is implicated in glycosaminoglycan binding. PCI in human or rhesus monkey plasma showed comparable inhibitory activity towards human activated protein C in the presence of 10 U/ml heparin. However, maximal acceleration of the inhibition of activated protein C required 5-fold lower heparin concentration for rhesus monkey than for human plasma, consistent with the interpretation that the additional positive charge (E13K) in a putative-heparin binding region increased the affinity for heparin.

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