Patterns of ascospore release in relation to phoma stem canker epidemiology in England (Leptosphaeria maculans) and Poland (Leptosphaeria biglobosa)

2005 ◽  
Vol 111 (3) ◽  
pp. 263-277 ◽  
Author(s):  
Yong-Ju Huang ◽  
Bruce D. L. Fitt ◽  
Malgorzata Jedryczka ◽  
Sylwia Dakowska ◽  
Jonathan S. West ◽  
...  
Keyword(s):  
Leptosphaeria Maculans ◽  
Stem Canker ◽  
Phoma Stem Canker ◽  
Ascospore Release ◽  
Leptosphaeria Biglobosa

scholarly journals Mycovirus-Induced Hypervirulence of Leptosphaeria biglobosa Enhances Systemic Acquired Resistance to Leptosphaeria maculans in Brassica napus

2020 ◽  
Vol 33 (1) ◽  
pp. 98-107 ◽  
Author(s):  
Unnati A. Shah ◽  
Ioly Kotta-Loizou ◽  
Bruce D. L. Fitt ◽  
Robert H. A. Coutts
Keyword(s):  
Brassica Napus ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Leptosphaeria Maculans ◽  
Stem Canker ◽  
Systemic Resistance ◽  
Phoma Stem Canker ◽  
Isogenic Lines ◽  
Related Proteins ◽  
Leptosphaeria Biglobosa

Phoma stem canker (blackleg) is one of the most important diseases of winter oilseed rape (Brassica napus) worldwide and is caused by a complex that comprises at least two species: Leptosphaeria maculans and L. biglobosa. Screening a panel of field Leptosphaeria isolates from B. napus for the presence of mycoviruses revealed the presence of a novel double-stranded RNA quadrivirus in L. biglobosa and no viruses in L. maculans. Following elimination of the mycovirus, virus-infected and virus-free isogenic lines of L. biglobosa were created. A direct comparison of the growth and virulence of these isogenic lines illustrated that virus infection caused hypervirulence and resulted in induced systemic resistance toward L. maculans in B. napus following lower leaf preinoculation with the virus-infected isolate. Analysis of the plant transcriptome suggests that the presence of the virus leads to subtle alterations in metabolism and plant defenses. For instance, transcripts involved in carbohydrate and amino acid metabolism are enriched in plants treated with the virus-infected isolate, while pathogenesis-related proteins, chitinases and WRKY transcription factors are differentially expressed. These results illustrate the potential for deliberate inoculation of plants with hypervirulent L. biglobosa to decrease the severity of Phoma stem canker later in the growing season. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

scholarly journals Occurrence of a New Subclade of Leptosphaeria biglobosa in Western Australia

2008 ◽  
Vol 98 (3) ◽  
pp. 321-329 ◽  
Author(s):  
L. Vincenot ◽  
M. H. Balesdent ◽  
H. Li ◽  
M. J. Barbetti ◽  
K. Sivasithamparam ◽  
...  
Keyword(s):  
Oilseed Rape ◽  
Mating Type ◽  
Western Australia ◽  
Leptosphaeria Maculans ◽  
Stem Canker ◽  
Tubulin Genes ◽  
Wide Scale ◽  
Scale Characterization ◽  
Leptosphaeria Biglobosa ◽  
Β Tubulin

Stem canker of crucifers is caused by an ascomycete species complex comprising of two main species, Leptosphaeria maculans and L. biglobosa. These are composed of at least seven distinct subclades based on biochemical data or on sequences of internal transcribed spacer (ITS), the mating type MAT1-2 or fragments of actin or β-tubulin genes. In the course of a wide-scale characterization of the race structure of L. maculans from Western Australia, a few isolates from two locations failed to amplify specific sequences of L. maculans, i.e., the mating-type or minisatellite alleles. Based on both pathogenicity tests and ITS size, these isolates were classified as belonging to the L. biglobosa species. Parsimony and distance analyses performed on ITS, actin and β-tubulin sequences revealed that these isolates formed a new L. biglobosa subclade, more related to the Canadian L. biglobosa ‘canadensis’ subclade than to the L. biglobosa ‘australensis’ isolates previously described in Australia (Victoria). They are termed here as L. biglobosa ‘occiaustralensis’. These isolates were mainly recovered from resistant oilseed rape cultivars that included the Brassica rapa sp. sylvestris-derived resistance source, but not from the susceptible cv. Westar. The pathogenicity of L. biglobosa ‘occiaustralensis’ to cotyledons of most oilseed rape genotypes was higher than that of L. biglobosa ‘canadensis’ or L. biglobosa ‘australensis’ isolates.

scholarly journals A New Subclade of Leptosphaeria biglobosa Identified from Brassica rapa

2019 ◽  
Vol 20 (7) ◽  
pp. 1668 ◽  
Author(s):  
Zhongwei Zou ◽  
Xuehua Zhang ◽  
Paula Parks ◽  
Lindsey du Toit ◽  
Angela Van de Wouw ◽  
...  
Keyword(s):  
Brassica Rapa ◽  
Phylogenetic Trees ◽  
Single Gene ◽  
Leptosphaeria Maculans ◽  
Stem Canker ◽  
Willamette Valley ◽  
Gene Sequences ◽  
Distance Analysis ◽  
Pathogenicity Tests ◽  
Leptosphaeria Biglobosa

Blackleg (Phoma stem canker) of crucifers is a globally important disease caused by the ascomycete species complex comprising of Leptosphaeria maculans and Leptosphaeria biglobosa. Six blackleg isolates recovered from Brassica rapa cv. Mizspoona in the Willamette Valley of Oregon were characterized as L. biglobosa based on standard pathogenicity tests and molecular phylogenetic analysis. These isolates were compared to 88 characterized L. biglobosa isolates from western Canada, 22 isolates from Australia, and 6 L. maculans isolates from Idaho, USA using maximum parsimony and distance analysis of phylogenetic trees generated from the ITS rDNA (internal transcribed spacer rDNA) sequence, and the actin and β-tubulin gene sequences. The L. biglobosa isolates derived from B. rapa collected in Oregon formed a separate subclade based on concatenated gene sequences or a single gene sequence, regardless of the analyses. Pathogenicity tests showed that these isolates failed to infect either resistant or susceptible B. napus cultivars, but caused severe symptoms on three B. rapa cultivars (Accession number: UM1113, UM1112, and UM1161), a B. oleracea var. capitata (cabbage) cultivar (Copenhagen Market), and two B. juncea cultivars (CBM, a common brown Mustard, and Forge). These findings demonstrated that the L. biglobosa isolates derived from a B. rapa crop in Oregon were genetically distinct from existing species of L. biglobosa, and constitute a new subclade, herein proposed as L. biglobosa ‘americensis’.

scholarly journals Forecasting system for infection risk of phoma stem canker in selected regions of the Czech Republic in 2009–2011 

2014 ◽  
Vol 50 (No. 1) ◽  
pp. 8-16 ◽  
Author(s):  
J. Poslušná ◽  
E. Plachká
Keyword(s):  
Czech Republic ◽  
Leaf Spot ◽  
Weather Conditions ◽  
Stem Canker ◽  
Infection Risk ◽  
Risk Of Infection ◽  
The Czech Republic ◽  
Phoma Stem Canker ◽  
Ascospore Release ◽  
Forecasting System

In the period 2009&ndash;2011 monitoring of the incidence of phoma stem canker was carried out at selected sites of the Czech Republic (&Scaron;umperk and Opava regions in North Moravia). The risk of infection was evaluated by assessing the autumn release of&nbsp;Leptosphaeria&nbsp;spp. ascospores and with the proPlant prediction model. In recent years, the incidence of phoma stem canker has been relatively low and this corresponded with the total count of ascospores released in the autumn period but not with an increased level of infection risk announced by the proPlant model. During the monitored period the ascospore concentration reached maximally 2 ascospores/1 m<sup>3</sup>&nbsp;per day. Maximum ascospore release was recorded in 2010 as a result of favourable weather conditions. The first incidence of phoma leaf spot has been observed in mid-October. The higher values of ascospores concentration were recorded in the Opava region, but the total number of the trapped ascospores was more often higher in the &Scaron;umperk region.&nbsp;

scholarly journals Effectiveness of Rlm7 resistance against Leptosphaeria maculans (phoma stem canker) in UK winter oilseed rape cultivars

2018 ◽  
Vol 67 (6) ◽  
pp. 1339-1353 ◽  
Author(s):  
G. K. Mitrousia ◽  
Y. J. Huang ◽  
A. Qi ◽  
S. N. M. Sidique ◽  
B. D. L. Fitt
Keyword(s):  
Oilseed Rape ◽  
Leptosphaeria Maculans ◽  
Stem Canker ◽  
Winter Oilseed Rape ◽  
Phoma Stem Canker
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