The Role of Phytoalexins in the Seedling Resistance to Leptosphaeria maculans in Some Crucifers

1995 ◽  
Vol 50 (1-2) ◽  
pp. 15-20 ◽  
Author(s):  
Michael Storck ◽  
Maria D. Sacristán
Keyword(s):  
Brassica Napus ◽  
Leptosphaeria Maculans ◽  
Brassica Species ◽  
Fungal Isolate ◽  
Time Intervals ◽  
Seedling Resistance ◽  
Sinapis Arvensis ◽  
Resistant Lines ◽  
Resistance Reaction

Abstract Brassica juncea, Brassica carinata and Sinapis arvensis resistant lines to Leptosphaeria maculans and four Brassica napus cuitivars susceptible to this pathogen in seedling stage were analyzed in relation to the accumulation of phytoalexins after inoculation with L. maculans. Cotyledon inoculations with spore suspensions of an aggressive and a non-aggressive isolate of L. maculans were performed on seedlings of these lines. The quantity of accumulated phytoalexins in the cotyledons was determined at different time intervals after inoculation. The content and composition of phytoalexins differed considerably among the tested species and according to the fungal isolate used. In the tested Brassica species seedling resistance against L. maculans could not be related to phytoalexin accumulation. However, in Sinapis arvensis phytoalexins might contribute to the resistance reaction to this pathogen.

Seedling and adult plant resistance to blackleg (Leptosphaeria maculans (Desm.) Ces. et de Not.) in spring rape (Brassica napus L.)

1980 ◽  
Vol 31 (1) ◽  
pp. 37 ◽  
Author(s):  
LA Cargeeg ◽  
N Thurling
Keyword(s):  
Brassica Napus ◽  
Leptosphaeria Maculans ◽  
Adult Plant ◽  
Selection Line ◽  
Selected Lines ◽  
Brassica Napus L ◽  
Seedling Resistance ◽  
Causal Organism ◽  
Resistant Lines ◽  
The Mean

In a glasshouse test with a large number of lines derived by self-pollination of rape plants (Brassica napus L.) randomly selected from each or four spring cultivars, considerable variation in the responses of seedlings to blackleg infection (causal organism Leptosphaeria maculans (Desm.) Ces. et de Not.) was observed between and within cultivars. Although the mean disease scores of lines within each cultivar ranged between the extremes of susceptibility and resistance, a much higher frequency of resistant lines were detected in the cultivar Nosovsky than in Ceska and Zollerngold. The lines used in this initial test provided a basis for developing a susceptible and resistant line from each cultivar, and these were tested together with six other lines previously rated as being resistant in the field, under both glasshouse and field conditions. Responses to seedling infection in four different glasshouse environments showed only three field-selected lines (Wesreo, Mutu and R46) to have adequate seedling resistance. All glasshouse-selected lines were susceptible in these glasshouse tests, and the resistant selections were In all cases slightly more susceptible than the corresponding susceptible selections. In the field test, the field-selected lines as a group were clearly more resistant than any of the glasshouse-selected lines except the Nosovsky resistant selection line. The Ceska and Zollerngold resistant selections, although susceptible in comparison with the field selections, were more resistant than the corresponding susceptible selections. Considerable variation in the mean disease scores of individual plants obtained at maturity was observed within all lines except the two Tower glasshouse selections. The frequency of resistant plants was fairly high in all field-selected lines except 73N22-1 and very low in all glasshouse-selected lines except the Nosovsky resistant selection. Coefficients of correlation between disease scores at maturity in the field and scores of young plants in each of four different glasshouse environments were significant for all but one environment. The highest correlation was observed in the case of the procedure involving a single inoculation 10 days after sowing and growth of seedlings under a daily temperature regime of 25/20�C. The five lines ranked most resistant in this test were also the five most resistant lines in the field.

Identifying resistance genes to Leptosphaeria maculans in Australian Brassica napus cultivars based on reactions to isolates with known avirulence genotypes

2012 ◽  
Vol 63 (4) ◽  
pp. 338 ◽  
Author(s):  
Steve J. Marcroft ◽  
Vicki L. Elliott ◽  
Anton J. Cozijnsen ◽  
Phillip A. Salisbury ◽  
Barbara J. Howlett ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Resistance Genes ◽  
Adult Plant Resistance ◽  
Leptosphaeria Maculans ◽  
Mortality Data ◽  
Adult Plant ◽  
Blackleg Disease ◽  
Seedling Resistance ◽  
Breeding Lines ◽  
Fungal Populations

Blackleg disease, caused by the fungus Leptosphaeria maculans, is the major disease of canola (Brassica napus) worldwide. A set of 12 Australian L. maculans isolates was developed and used to characterise seedling resistance in 127 Australian cultivars and advanced breeding lines. Plant mortality data used to assess the effectiveness of seedling resistance in canola growing regions of Australia showed that Rlm3 and Rlm4 resistance genes were less effective than other seedling resistance genes. This finding was consistent with regional surveys of the pathogen, which showed the frequency of Rlm4-attacking isolates was >70% in fungal populations over a 10-year period. Differences in adult plant resistance were identified in a subset of Australian cultivars, indicating that some adult gene resistance is isolate-specific.

Effect of root rot and stem canker caused by Leptosphaeria maculans on yield of Brassica napus and measures for control in the field

2010 ◽  
Vol 61 (1) ◽  
pp. 50 ◽  
Author(s):  
S. J. Sprague ◽  
J. A. Kirkegaard ◽  
B. J. Howlett ◽  
J. Graham
Keyword(s):  
Brassica Napus ◽  
Grain Yield ◽  
Root Rot ◽  
Field Experiments ◽  
Management Strategies ◽  
Leptosphaeria Maculans ◽  
Brassica Species ◽  
Grain Filling ◽  
Stem Canker ◽  
Eastern Australia

Leptosphaeria maculans causes blackleg of Brassica napus (canola), manifesting in symptoms including leaf lesions, stem canker, and root rot. Root rot is an extension of the stem canker phase of the disease resulting from foliar infection; however, the role of root rot in grain yield loss has not been investigated. Field experiments were conducted in south-eastern Australia to determine the efficacy of fungicides and host resistance to stem canker for the control of root rot, along with the association between root rot severity and grain yield. Fungicides applied as a seed dressing (fluquinconazole) or coated on fertiliser (flutriafol) reduced root rot severity by 16 and 41%, respectively. Root rot severity was 78% less in a B. napus cultivar with an Australian Blackleg Rating (ABR) of 9.0 (highly resistant to stem canker) than in a moderately resistant cultivar (ABR 5.5), and was also reduced in Brassica species with good resistance to stem canker. Root rot caused little or no additional reduction in yield or harvest index of individual B. napus plants above that caused by stem canker. Individual upright plants with greater than 80% of the stem cross-section blackened had significantly reduced seed yield; however, this was influenced by rainfall during the grain-filling period. This study shows that current management strategies for stem canker caused by L. maculans also control root rot in B. napus, as although the symptoms in roots are severe, these symptoms have no additional effect on yield.

The role of pycnidiospores of Leptosphaeria maculans in the spread of blackleg disease in rape

1976 ◽  
Vol 16 (83) ◽  
pp. 911 ◽  
Author(s):  
MJ Barbetti
Keyword(s):  
Brassica Napus ◽  
Leptosphaeria Maculans ◽  
Field Conditions ◽  
Disease Spread ◽  
Blackleg Disease ◽  
Leaf Infection ◽  
Infection Spread

The development and spread of blackleg leaf, stem and crown infections in rape plants (Brassica napus cv. Zephyr), caused by Leptosphaeria maculans pycnidiospores, was examined under field conditions for plants artificially inoculated at 3, 5 1/2 and 8 1/2 weeks of age. Spread of leaf, stem and crown infections, via pycnidiospores, occurred for inoculations made on 3- and 5 1/2-week-old plants. Inoculation at three weeks oflage resulted in theigreatest disease spread. There was no leaf infection spread and very little stem and crown infection spread for the inoculation made on the 8 1/2-week-old plants.

scholarly journals A Field Method for Evaluating the Potential Durability of New Resistance Sources: Application to the Leptosphaeria maculans-Brassica napus Pathosystem

2000 ◽  
Vol 90 (9) ◽  
pp. 961-966 ◽  
Author(s):  
H. Brun ◽  
S. Levivier ◽  
I. Somda ◽  
D. Ruer ◽  
M. Renard ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Field Experiment ◽  
Resistance Genes ◽  
Leptosphaeria Maculans ◽  
Rapid Change ◽  
Natural Populations ◽  
Field Method ◽  
Addition Line ◽  
Resistant Lines ◽  
High Level

To increase the longevity of new resistance genes by avoiding a rapid change in pathogen populations, we established a new field method to determine, before the release of a resistant cultivar, whether and how rapidly the pathogen population is capable of responding to the selective pressure we impose. This method was applied to the Leptosphaeria maculans-Brassica napus pathosystem. The potential durability of two new major resistance genes introgressed into B. napus from the Brassica B genome was tested separately for each gene under field conditions for 4 years. Successive inoculations with residues of the resistant lines mixed with susceptible contaminated plant material recovered at harvest the previous year were performed in autumn. The Jlm1 resistance gene originating from B. juncea conferred complete resistance on the B. napus-B. juncea recombinant lines MX and MXS to inoculation of the cotyledons with a large diversity of L. maculans isolates. It also gave a high level of stem canker resistance in the field against natural populations of the pathogen. A similar level of resistance was obtained in the B. napus-B. nigra addition line LA4+, containing B. nigra chromosome 4 in a B. napus background. In the second year of the field experiment (i.e., the first in which residues from the resistant lines were included in the inoculation material), both MX and LA4+ maintained a high level of resistance. In the third and fourth years of the field experiment, the resistance of MX and MXS exposed to inoculum produced from their own residues broke down, but against fungal populations from susceptible B. napus or resistant B. nigra material remained effective. In contrast, LA4+ remained highly resistant to all sources of inoculum for the 4-year experiment.

Role of Histamine and Leucotaxin in Function of Cellular Defense Mechanism

1956 ◽  
Vol 184 (2) ◽  
pp. 296-300 ◽  
Author(s):  
László Kátó ◽  
Béla Gözsy
Keyword(s):  
Fluid Flow ◽  
Tissue Damage ◽  
Inflammatory Process ◽  
Defense Mechanism ◽  
Volatile Oils ◽  
Time Intervals ◽  
Cellular Defense ◽  
Intradermal Administration ◽  
Flow Through

Experiments are presented to the effect that in an inflammatory process histamine and leucotaxin appear successively at different and orderly time intervals, thus assuring an increased fluid flow through the capillary wall. Histamine is released not only in the inflammatory process but also by intradermal administration of such substances (volatile oils or their components) which induce neither the triple response of Th. Lewis nor any tissue damage. This could be explained by the fact that in the tissues histamine is ‘present’ but leucotaxin is ‘formed.’

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.

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

Sign in / Sign up

Export Citation Format

Share Document