scholarly journals An avirulence gene,AvrLmJ1, from the blackleg fungus,Leptosphaeria maculans, confers avirulence toBrassica junceacultivars

2013 ◽  
Vol 15 (5) ◽  
pp. 523-530 ◽  
Author(s):  
Angela P. Van de Wouw ◽  
Rohan G. T. Lowe ◽  
Candace E. Elliott ◽  
David J. Dubois ◽  
Barbara J. Howlett
Keyword(s):  
Leptosphaeria Maculans ◽  
Avirulence Gene ◽  
Blackleg Fungus

scholarly journals Fungicide sensitivity and resistance in the blackleg fungus, Leptosphaeria maculans, across canola growing regions in Australia

2021 ◽  
Author(s):  
A. P. Van de Wouw ◽  
J. L. Scanlan ◽  
S. J. Marcroft ◽  
A. J. Smith ◽  
E. M. Sheedy ◽  
...  
Keyword(s):  
Leptosphaeria Maculans ◽  
Fungicide Sensitivity ◽  
Blackleg Fungus

scholarly journals Analysis of Molecular Markers Genetically Linked to the Leptosphaeria maculans Avirulence Gene AvrLm1 in Field Populations Indicates a Highly Conserved Event Leading to Virulence on Rlm1 Genotypes

2002 ◽  
Vol 15 (7) ◽  
pp. 672-682 ◽  
Author(s):  
Agnès Attard ◽  
Lilian Gout ◽  
Mathieu Gourgues ◽  
Marie-Line Kühn ◽  
Jacques Schmit ◽  
...  
Keyword(s):  
Genetic Map ◽  
Large Scale ◽  
Polymerase Chain Reaction Amplification ◽  
Leptosphaeria Maculans ◽  
Avirulence Gene ◽  
Bac Contig ◽  
Genome Region ◽  
Repulsion Phase ◽  
Field Isolates

Map-based cloning of the avirulence gene AvrLm1 of Leptosphaeria maculans was initiated utilizing a genetic map of the fungus and a BAC library constructed from an AvrLm1 isolate. Seven polymorphic DNA markers closely linked to AvrLm1 were identified. Of these, two were shown to border the locus on its 5′ end and were present, with size polymorphism, in both the virulent and the avirulent isolates. In contrast, three markers, J19-1.1, J53-1.3 (in coupling phase with avirulence), and Vir1 (in repulsion phase with avirulence), cosegregated with AvrLm1 in 312 progeny from five in vitro crosses. J19-1.1 and J53-1.3 were never amplified in the virulent parents or progeny, whereas Vir1 was never amplified in the avirulent parents or progeny. J19-1.1 and J53-1.3 were shown to be separated by 40 kb within a 184-kb BAC contig. In addition, the 1.6-cM genetic distance between J53-1.3 and the nearest recombinant marker corresponded to a 121-kb physical distance. When analyzing a European Union-wide collection of 192 isolates, J53-1.3, J19-1.1, and Vir1 were found to be closely associated with the AvrLm1 locus. The results of polymerase chain reaction amplification with primers for the three markers were in accordance with the interaction phenotype for 92.2% (J53-1.3), 90.6% (J19-1.1), and 88.0% (Vir1) of the isolates. In addition, genome organization of the AvrLm1 region was highly conserved in field isolates, because 89.1% of the avirulent isolates and 79.0% of the virulent isolates showed the same association of markers as that of the parents of in vitro crosses. The large-scale analysis of field isolates with markers originating from the genetic map therefore confirms (i) the physical proximity between the markers and the target locus and (ii) that AvrLm1 is located in (or close to) a recombination-deficient genome region. As a consequence, map-based markers provided us with high-quality markers for an overview of the occurrence of race “AvrLm1” at the field scale. These data were used to propose hypotheses on evolution towards virulence in field isolates.

Prevalence of blackleg (Leptosphaeria maculans) on canola (Brassica napus) in Western Australia

2001 ◽  
Vol 41 (1) ◽  
pp. 71 ◽  
Author(s):  
R. K. Khangura ◽  
M. J. Barbetti
Keyword(s):  
Western Australia ◽  
Disease Incidence ◽  
Leptosphaeria Maculans ◽  
Sowing Date ◽  
Blackleg Disease ◽  
The Mean ◽  
Seed Yields ◽  
Blackleg Fungus ◽  
Western Australian

Canola crops were monitored throughout the Western Australian wheatbelt during 1996–99 to determine the incidence and severity of crown cankers caused by the blackleg fungus (Leptosphaeria maculans). All crops surveyed had blackleg. The incidence of crown canker was 48–100%, 15–100%, 9–94% and 48–100% during 1996, 1997, 1998 and 1999, respectively. The mean incidence of crown cankers statewide was 85, 63, 55 and 85% in 1996, 1997, 1998 and 1999, respectively. The severity of crown canker (expressed as percentage disease index) ranged between 30 and 96%, 3 and 94%, 5 and 78% and 21 and 96% during 1996, 1997, 1998 and 1999, respectively. These high levels of blackleg can possibly be attributed to the accumulation of large amounts of infested canola residues. In 1999, there were effects of variety, application of the fungicide Impact, distance to last year’s canola residues and rainfall on the incidence and severity of blackleg. However, there were no effects of sowing date or region on the disease incidence or severity once the other factor effects listed above had been considered. In 1995, an additional survey of 19 sites in the central wheatbelt of Western Australia assessed the survival of the blackleg fungus on residues from crops grown in 1992–94. The residues at all sites carried blackleg. However, the extent of infection at any particular site varied from 12 to 100% of stems with the percentage of stems carrying pseudothecia containing ascospores varying between 7 and 96%. The high levels of blackleg disease found in commercial crops are indicative of significant losses in seed yields, making it imperative that management of blackleg be improved if canola is to remain a viable long-term cropping option in Western Australia.

scholarly journals Impact of Cruciferous Phytoalexins on the Detoxification of Brassilexin by the Blackleg Fungus Pathogenic to Brown Mustard

2010 ◽  
Vol 5 (6) ◽  
pp. 1934578X1000500
Author(s):  
M. Soledade C. Pedras ◽  
Ryan B. Snitynsky
Keyword(s):  
Brassica Juncea ◽  
Leptosphaeria Maculans ◽  
Fungal Species ◽  
Important Group ◽  
Blackleg Fungus

The biotransformation of brassilexin, a potent phytoalexin produced by brown mustard (Brassica juncea L.), in the presence of various cruciferous phytoalexins was investigated. An important group of isolates of the fungal species Leptosphaeria maculans (Laird 2 and Mayfair 2), which is virulent to brown mustard, but not to canola, was used in this investigation. Brassilexin was detoxified by the fungus, but none of the phytoalexins seemed to affect substantially the rate of brassilexin detoxification; after 12 h of incubation, the amounts of brassilexin remaining in culture were as low as in controls, except in co-incubations with cyclobrassinin and sinalexin, which afforded intermediates that in solution oxidized spontaneously to brassilexin.

Variation in the responses of rapeseed (Brassica napus and B. campestris) cultivars to blackleg (Leptosphaeria maculans) infection

1977 ◽  
Vol 17 (86) ◽  
pp. 445 ◽  
Author(s):  
N Thurling ◽  
LA Venn
Keyword(s):  
Brassica Napus ◽  
Significant Variation ◽  
Brassica Campestris ◽  
Leptosphaeria Maculans ◽  
The Other ◽  
Controlled Environment ◽  
Disease Development ◽  
Fungal Populations ◽  
Different Populations ◽  
Blackleg Fungus

The responses of 53 cultivars of the rapeseed species Brassica napus and Brassica campestris to infection by three different populations of the blackleg fungus, Leptosphaeria maculans, were examined in a controlled environment. Significant variation in disease development was observed between cultivars as well as between fungal populations which had been derived from diseased stubble collected at widely separated sites in Western Australia. A large proportion of the cultivars tested were either susceptible or only slightly resistant to infection by each of the three fungal populations whereas only one cultivar, Zollerngold, was highly resistant to all fungal populations. Several other cultivars, however, were resistant to one population and susceptible or slightly resistant to the other two. In these cases, marked interactions between host and parasite were evident, some cultivars being substantially more resistant than others to infection by spores from a particular population.

Factors affecting production of inoculum of the blackleg fungus (Leptosphaeria maculans) in south-eastern Australia

2003 ◽  
Vol 43 (10) ◽  
pp. 1231 ◽  
Author(s):  
S. J. Marcroft ◽  
S. J. Sprague ◽  
S. J. Pymer ◽  
P. A. Salisbury ◽  
B. J. Howlett
Keyword(s):  
Management Strategy ◽  
Leptosphaeria Maculans ◽  
Soil Surface ◽  
Factors Affecting ◽  
High Rainfall ◽  
South Eastern ◽  
Eastern Australia ◽  
Blackleg Fungus ◽  
South Eastern Australia

The production of windborne ascospore inoculum of the blackleg fungus (Leptosphaeria maculans) was determined during 2000 and 2001 in 3 environments (Birchip, low rainfall; Wonwondah, medium rainfall; Lake Bolac, high rainfall) in Victoria. The weight of canola stubble (kg/ha) remaining on the soil surface in paddocks was estimated 6, 18, 30 and 42 months after harvest of the original canola crop. In all 3 environments only small amounts of stubble were present 18 months after harvest. Eighty percent of the 6-month-old stubble comprised stems and branches, with the remaining 20% being root material, while 42-month-old stubble consisted only of root material. Paddocks subjected to raking and burning contained only half the weight of stubble compared with paddocks that were harrowed. Where canola was harvested in January, even when no management strategy was used, 80% of subsequent stubble was no longer on the soil surface by July of that year. Pseudothecia from 6-month-old stubble from the high rainfall environment discharged significantly more ascospores than stubble of the same age from the medium rainfall environment, which in turn discharged more than stubble from the low rainfall environment. In all environments, paddocks containing 6-month-old canola stubble discharged 30-fold as many ascospores per hectare as older stubble paddocks.

scholarly journals Genetic Analysis and Identification of Amplified Fragment Length Polymorphism Markers Linked to the alm1 Avirulence Gene of Leptosphaeria maculans

1998 ◽  
Vol 88 (10) ◽  
pp. 1068-1072 ◽  
Author(s):  
Patchara Pongam ◽  
Thomas C. Osborn ◽  
Paul H. Williams
Keyword(s):  
Length Polymorphism ◽  
Fragment Length ◽  
Fragment Length Polymorphism ◽  
Leptosphaeria Maculans ◽  
Amplified Fragment Length Polymorphism ◽  
Gene Interaction ◽  
Aflp Markers ◽  
Avirulence Gene ◽  
Resistance Locus ◽  
Gene For Gene

A gene-for-gene interaction was previously suggested by mapping of a single major locus (LEM 1) controlling cotyledon resistance to Leptosphaeria maculans isolate PHW1245 in Brassica napus cv. Major. In this study, we obtained further evidence of a gene-for-gene interaction by studying the inheritance of the corresponding avirulence gene in L. maculans isolate PHW1245. The analysis of segregating F1 progenies and 14 test crosses suggested that a single major gene is involved in the interaction. This putative avirulence gene was designated alm1 after the resistance locus identified in B. napus. Amplified fragment length polymorphism (AFLP) markers were used to generate a rudimentary genetic linkage map of the L. maculans genome and to locate markers linked to the putative avirulence locus. Two flanking AFLP markers, AC/TCC-1 and AC/CAG-5, were linked to alm1 at 3.1 and 8.1 cM, respectively. Identification of markers linked to the avirulence gene indicated that the differential interaction is controlled by a single gene difference between parental isolates and provides further support for the gene-for-gene relationship in the Leptosphaeria-Brassica system.

Genetic mapping of the Leptosphaeria maculans avirulence gene corresponding to the LepR1 resistance gene of Brassica napus

2011 ◽  
Vol 124 (3) ◽  
pp. 505-513 ◽  
Author(s):  
Kaveh Ghanbarnia ◽  
Derek J. Lydiate ◽  
S. Roger Rimmer ◽  
Genyi Li ◽  
H. Randy Kutcher ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Genetic Mapping ◽  
Resistance Gene ◽  
Leptosphaeria Maculans ◽  
Avirulence Gene

Small scale functional genomics of the blackleg fungus, Leptosphaeria maculans: analysis of a 38 kb region

2003 ◽  
Vol 32 (4) ◽  
pp. 511 ◽  
Author(s):  
Alexander Idnurm ◽  
Janet L. Taylor ◽  
M. Soledade C. Pedras ◽  
Barbara J. Howlett
Keyword(s):  
Functional Genomics ◽  
Leptosphaeria Maculans ◽  
Small Scale ◽  
Blackleg Fungus
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