Adaptability and virulence specificity in Australian strains of blackleg [Leptosphaeria maculans (Desm.) Ces. et De Not.] on different host genotypes of rapeseed (Brassica napus L.)

1995 ◽  
Vol 46 (5) ◽  
pp. 971 ◽  
Author(s):  
ECK Pang ◽  
GM Halloran
Keyword(s):  
Brassica Napus ◽  
Virulence Genes ◽  
Leptosphaeria Maculans ◽  
Lesion Size ◽  
Lesion Area ◽  
Brassica Napus L ◽  
Screening Programs ◽  
Regression Techniques ◽  
Glasshouse Screening ◽  
Specific Virulence

Five clone-lines of rapeseed (Brassica napus L.) were artificially inoculated with 24 isolates of blackleg (Leptosphaeria maculans (Desm.) Ces. et De Not.) from 12 sites around Australia to determine the proportion of virulence genes in L. maculans which interacted with genes for specific resistance in B. napus. Resistance/susceptibility was evaluated both as external lesion size (%G) and internal lesion area (%II) of individual plants of the clone-lines. Using two different regression techniques (stability analysis) involving levels of infection caused by the isolates on the clone-lines, isolates were ranked according to levels of specific virulence. There were differences in stability between isolates in their capacity to exhibit consistent virulence over the range of genotypes used. Using deviations from regression as an indicator of the proportion of genes for specific- and non-specific virulence, it was observed that a third of all isolates used possessed significant levels of specific virulence. The significance of this finding in relation to glasshouse screening programs for blackleg resistance is discussed.

Development of an agronomically superior blackleg resistant canola cultivar in Brassica napus L. using doubled haploidy

1995 ◽  
Vol 75 (2) ◽  
pp. 437-439 ◽  
Author(s):  
G. R. Stringam ◽  
V. K. Bansal ◽  
M. R. Thiagarajah ◽  
D. F. Degenhardt ◽  
J. P. Tewari
Keyword(s):  
Brassica Napus ◽  
Doubled Haploid ◽  
Leptosphaeria Maculans ◽  
Resistance Breeding ◽  
Breeding Method ◽  
Brassica Napus L ◽  
Breeding Lines ◽  
University Of Alberta ◽  
Blackleg Resistance ◽  
The University

The doubled haploid breeding method and greenhouse screening using cotyledon bio-assay were successfully applied to transfer blackleg resistance from the Australian cultivar Maluka (Brassicas napus), into susceptible advanced B. napus lines from the University of Alberta. This approach for blackleg resistance breeding was effective and efficient as several superior blackleg resistant breeding lines were identified within 4 yr from the initial cross. One of these lines (91–21864NA) was entered in the 1993 trials of the Western Canada Canola/Rapeseed Recommending Committee. Key words: Blackleg resistance, Leptosphaeria maculans, doubled haploid, Brassica napus

Association mapping of quantitative resistance for Leptosphaeria maculans in oilseed rape (Brassica napus L.)

2010 ◽  
Vol 27 (3) ◽  
pp. 271-287 ◽  
Author(s):  
C. Jestin ◽  
M. Lodé ◽  
P. Vallée ◽  
C. Domin ◽  
C. Falentin ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Association Mapping ◽  
Oilseed Rape ◽  
Quantitative Resistance ◽  
Leptosphaeria Maculans ◽  
Brassica Napus L

The teleomorph of the weakly aggressive segregate ofLeptosphaeriamaculans

2001 ◽  
Vol 79 (4) ◽  
pp. 412-419 ◽  
Author(s):  
R A Shoemaker ◽  
Hortense Brun
Keyword(s):  
New Species ◽  
Brassica Napus ◽  
Helianthus Annuus ◽  
Leptosphaeria Maculans ◽  
Interspecific Crosses ◽  
Phoma Lingam ◽  
Type Specimens ◽  
Brassica Napus L ◽  
Weakly Virulent ◽  
Leptosphaeria Biglobosa

Leptosphaeria biglobosa n.sp. is described for the weakly virulent (or non-aggressive) pathogen causing blackleg of oilseed rape and canola. The new species differs from the aggressive blackleg organism, Leptosphaeria maculans (Desm.) Ces. & De Not. in having a very prominent beak on the ascomata that is greatly enlarged at the apex. Ascomata of both species were produced on canola stems either by inoculation of compatible strains of the Phoma anamorph or by single ascospore isolates at a distance of 1 cm and letting them grow together. Both species exhibit bipolar heterothallism. Interspecific crosses were negative. In a study of type specimens of Leptosphaeria species with 5-septate ascospores infecting Cruciferae, none were found that matched the features of L. biglobosa. Leptosphaeria napi (Fuckel) Saccardo on Brassica napus L., and Leptosphaeria virginica (Cooke & Ellis) Saccardo on Lepidium virginica L., are synonyms of L. maculans. Leptosphaeria submaculans Holm on Sisymbrium, Berteroa, and Erysimum has distinctively enlarged ascospores. Leptosphaeria alliariae (Desm.) Ces. & De Not. on Alliaria officinalis Andrz., has much smaller ascospores. Leptosphaeria lindquistii Frezzi on Helianthus annuus L. of the Asteraceae has ascospores with only one, two, or rarely, three septa but was considered because it too has a Phoma anamorph.Key words: Phoma lingam, B group, ascomata.

Molecular mapping and validation of Rlm1 gene for resistance to Leptosphaeria maculans in canola (Brassica napus L.)

2012 ◽  
Vol 63 (10) ◽  
pp. 1007 ◽  
Author(s):  
Rosy Raman ◽  
Belinda Taylor ◽  
Kurt Lindbeck ◽  
Neil Coombes ◽  
Denise Barbulescu ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Ssr Markers ◽  
Genomic Sequence ◽  
Molecular Mapping ◽  
Durable Resistance ◽  
Leptosphaeria Maculans ◽  
Doubled Haploid Population ◽  
Brassica Napus L ◽  
Breeding Populations ◽  
Independent Population

European winter canola (Brassica napus L.) cultivars harbour genes for durable resistance to the fungus Leptosphaeria maculans, which causes blackleg disease under Australian environmental conditions. Previous studies have shown that resistance in winter-type cultivars Maxol and Columbus is controlled by two genes, Rlm1 and Rlm3, which have been mapped using randomly amplified polymorphic DNA markers onto chromosome A7. We mapped a doubled-haploid population that consisted of 101 lines from a cross between Maxol*1 and Westar-10 using diversity arrays technology and simple sequence repeat (SSR)-based markers. Two SSR marker loci, Xol12-e03 and Xra2-a05b, flanked the Rlm1 locus at an interval of 6.7 cM, which corresponds to ~3.2 Mb of the Brassica rapa genomic sequence; this region contains several genes encoding putative kinase and leucine-rich repeat-type disease-resistance proteins. SSR markers were further tested for their linkage with the Rlm1 locus in an independent population derived from Columbus*3/Westar-10. Our results showed that SSR markers linked to Rlm1 can be useful for monitoring Rlm1 gene introgression in breeding populations derived from Maxol and Columbus.

scholarly journals Strains of Leptosphaeria maculans with the Capacity to Cause Crown Canker on Brassica carinata are Present in Western Australia

Plant Disease ◽  
2006 ◽  
Vol 90 (6) ◽  
pp. 832-832
Author(s):  
R. Khangura ◽  
M. Aberra
Keyword(s):  
Western Australia ◽  
Leptosphaeria Maculans ◽  
Lesion Size ◽  
Hypersensitive Reaction ◽  
Adult Plant ◽  
Conidial Suspension ◽  
Pressure Potential ◽  
Brassica Napus L ◽  
Blackleg Resistance ◽  
B Genome

Blackleg, caused by Leptosphaeria maculans (Desm.) Ces. et de Not., is the most important disease of canola (Brassica napus L.) in Australia, Europe, Canada, and North America (2). During the early 1990s, new cultivars of canola with resistance to blackleg were released in Australia. Despite good adult-plant resistance, these cultivars still suffered significant yield losses from blackleg under high disease pressure. Potential new sources of blackleg resistance such as B. nigra L., B. carinata L., and Sinapis alba L. are being evaluated. B. carinata is believed to be highly resistant to blackleg by virtue of its B-genome. However, some L. maculans isolates that can attack B. carinata have been reported from Germany (1). During the 2003 growing season, 22 isolates of L. maculans were collected from different canola-growing areas of Western Australia and tested for their reaction on 24 seedlings of each of various Brassica genotypes, including B. carinata, in a controlled environment chamber. Twenty-four seeds per genotype were sown in 100-ml plastic pots (12 seeds per pot) and both cotyledons of 10-day-old seedlings were wound inoculated with a conidial suspension (1 × 107 conidia/ml) of each isolate of L. maculans. Disease assessments were made 2 weeks after inoculation. The majority of isolates induced a noninvasive hypersensitive reaction on B. carinata without pycnidial development. However, four of the isolates caused lesions with abundant pycnidia on B. carinata cotyledons. The lesion size ranged between 3 and 7 mm and appeared similar to that on susceptible B. napus cultivars. B. carinata seedlings were grown for another 8 weeks in a glasshouse, and crown cankers were observed from plants inoculated with three of the four seedling virulent isolates. The severity of crown cankers as percent of stem circumference (percent disease index) ranged between 20 and 54%. Twenty-five stem pieces from mature B. carinata plants infected with one of the three isolates were plated on V8 juice agar and L. maculans was recovered from 70% of pieces. Abundant pycnidia were also observed on these stem pieces. These results have important implications for using B. carinata as a source of blackleg resistance in canola breeding. To our knowledge, this is the first report of L. maculans isolates with the capacity to induce crown cankers on B. carinata in Australia. References: (1) C. Sjöidin and K. Glimelius. J. Phytopathol. 123:322, 1988. (2) J. West et al. Plant Pathol. 51:454, 2002.

Evaluation of pyraclostrobin as a component in seed and foliar fungicides for the management of blackleg (Leptosphaeria maculans) of canola (Brassica napus)

2020 ◽  
Vol 100 (5) ◽  
pp. 549-559
Author(s):  
Michelle Fraser ◽  
Stephen E. Strelkov ◽  
George D. Turnbull ◽  
Hafiz U. Ahmed ◽  
Wayne Barton ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Untreated Control ◽  
Seed Treatment ◽  
Fungal Pathogens ◽  
Leptosphaeria Maculans ◽  
Susceptible Cultivar ◽  
Brassica Napus L ◽  
Yield Increase ◽  
Novel Target ◽  
Stem Cankers

Infection by Leptosphaeria maculans (Desm.) Ces. & de Not., the causal agent of blackleg of canola (Brassica napus L.), can result in seedling death, foliar lesions, and the development of stem cankers on adult plants. Strobilurin fungicides such as pyraclostrobin are popular, as they are effective against a broad range of fungal pathogens, have novel target specificity, and translaminar activity within the plant. The seed treatment Prosper FX (carbathiin + trifloxystrobin + metalaxyl) and an experimental formulation BAS 720 F (pyraclostrobin + fluxapyroxad + metalaxyl) were evaluated for their efficacy in managing blackleg when applied alone or in combination with the foliar fungicides Priaxor (pyraclostrobin + fluxapyroxad) or Tilt 250 EC (propiconazole). Experiments were conducted with the blackleg-susceptible cultivar ‘Westar’ and the moderately resistant cultivar ‘Dekalb 73-15 RR’ under greenhouse and field conditions in 2012 and 2013. In one greenhouse trial, all fungicide treatments significantly reduced stem blackleg severity on ‘73-15’ and ‘Westar’ compared with the inoculated–untreated controls. During 3 of 4 site-years, the combination of the experimental seed treatment BAS 720 F and Priaxor significantly reduced stem disease severity relative to the inoculated–untreated control by 60%–77% for ‘73-15’ and by 50%–75% for ‘Westar’. This treatment also resulted in a significant yield increase relative to the inoculated–untreated control in ‘Westar’ in 2 site-years by 24% and 56%. The results of the study suggest a reduction in blackleg symptoms and improved yields when canola is treated with a combination of seed and foliar fungicides, especially when cropping a susceptible cultivar.

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