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.

scholarly journals Induced Resistance to Blackleg (Leptosphaeria maculans) Disease of Canola (Brassica napus) Caused by a Weakly Virulent Isolate of Leptosphaeria biglobosa

Plant Disease ◽  
2006 ◽  
Vol 90 (8) ◽  
pp. 1059-1064 ◽  
Author(s):  
Y. Chen ◽  
W. G. D. Fernando
Keyword(s):  
Brassica Napus ◽  
Field Experiments ◽  
Leptosphaeria Maculans ◽  
Fungal Species ◽  
Control Treatment ◽  
Water Control ◽  
Pathogenicity Group ◽  
Weakly Virulent ◽  
Leptosphaeria Biglobosa ◽  
Highly Virulent

Blackleg of canola is a disease complex of at least two fungal species: Leptosphaeria maculans and L. biglobosa. Isolates of L. biglobosa typically are weakly virulent or avirulent and are assigned to pathogenicity group 1 (PG-1). Isolates of L. maculans are highly virulent and encompass pathogenicity groups PG-2, PG-3, and PG-4. In greenhouse tests, percent lesion/leaf area (PLLA) on cotyledons of two Brassica napus cultivars, Westar and Invigor 2153, was smaller when L. biglobosa (PG-1) was either pre- or co-inoculated at 0, 12, 24, and 48 h with virulent isolates of L. maculans in PG-2, PG-3, and PG-4. On six-leaf-stage plants of Westar, the PLLA declined significantly compared with the control when the lower leaves were treated with either PG-1 or salicylic acid, then challenged with a PG-2 isolate 24 h later. In addition, the activity of four enzymes (chitinase, β-1,3-glucanase, peroxidase, and phenylalanine ammonia lyase) was greatly enhanced at 48 and 72 h when cotyledons of Westar were inoculated first with PG-1 followed by PG-2 24 h later, compared with a water control treatment. Field experiments conducted in 2003 and 2004 showed decreased blackleg severity in plants inoculated with PG-1 alone or prior to PG-2 compared with plants inoculated with PG-2 alone or prior to PG-1.

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

A STUDY OF ERUCIC ACID ALLELES IN DIGENOMIC RAPESEED (Brassica napus L.)

1981 ◽  
Vol 61 (2) ◽  
pp. 198-202 ◽  
Author(s):  
I. J. ANAND ◽  
R. K. DOWNEY
Keyword(s):  
Fatty Acid ◽  
Brassica Napus ◽  
Erucic Acid ◽  
Direct Evidence ◽  
Brassica Campestris ◽  
Fatty Acid Analysis ◽  
Interspecific Crosses ◽  
Seed Oils ◽  
Brassica Napus L ◽  
Brassica Crops

Five genes have been identified in Brassica crops which control the level of synthesis of the fatty acid, erucic, in their seed oils. These genes, designated e, Ea, Eb, Ec, and Ed, act in an additive manner and result in erucic acid levels of < 1, 10, 15, 30 and 3.5, respectively. No direct evidence has yet been obtained to show that these genes are true alleles. Selected plants of the amphidiploid species Brassica napus L. with erucic acid contents of 7–8% and a genotype of EdEdee were reciprocally crossed with selected plants with erucic acid levels of [Formula: see text] and a genotype of Eaeee. Fatty acid analysis of F1 and backcross seed demonstrated that the genes Ed and Ea in the parents used were in the same genome and were truly allelic. Interspecific crosses were made between these B. napus parents and selected zero erucic acid plants of Brassica campestris L. (genotype "ee") to determine whether the genes Ed and Ea resided in the oleracea or the campestris genome of B. napus parents. Fatty acid analysis of F1 and backcross seed from these interspecific crosses suggest that the alleles of Ed and Ea are located on chromosomes of the oleracea genome.

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 Characterization of Callose Deposition and Analysis of the Callose Synthase Gene Family of Brassica napus in Response to Leptosphaeria maculans

2018 ◽  
Vol 19 (12) ◽  
pp. 3769 ◽  
Author(s):  
Fei Liu ◽  
Zhongwei Zou ◽  
W. Fernando
Keyword(s):  
Brassica Napus ◽  
Expression Patterns ◽  
Critical Role ◽  
Leptosphaeria Maculans ◽  
Tissue Expression ◽  
Callose Synthase ◽  
Callose Deposition ◽  
Protein Properties ◽  
Gene Structures ◽  
Leptosphaeria Biglobosa

Callose plays a critical role in different biological processes including development as well as in the response to multiple biotic and abiotic stresses. In this study, we characterized the callose deposition in cotyledons of different Brassica napus varieties post-inoculated with different Leptosphaeria maculans isolates. Further, members of the callose synthase gene were identified from the whole genome of B. napus using the 12 Arabidopsis thaniana callose synthase protein sequences, and were then classified into three groups based on their phylogenetic relationships. Chromosomal location and duplication patterns indicated uneven distribution and segmental duplication patterns of BnCalS genes in the B. napus genome. Subsequently, gene structures, conserved domains analysis, and protein properties were analyzed for BnCalS genes. In addition, 12 B. napus orthologs of the AtCalS were selected for investigating the tissue expression pattern, indicating diverse expression patterns for these BnCalS genes. Responses of the selected 12 orthologs and all the BnCalS genes were characterized in the different types (AvrLm1-Rlm1, AvrLm4-Rlm4, AvrLepR1-LepR1) of B. napus–L. maculans interactions and B. napus-Leptosphaeria biglobosa interactions, implying their potential roles in response to Leptosphaeria infection.

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
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