Mapping genes for resistance to Leptosphaeria maculans in Brassica juncea

Genome ◽  
2006 ◽  
Vol 49 (1) ◽  
pp. 30-41 ◽  
Author(s):  
J A Christianson ◽  
S R Rimmer ◽  
A G Good ◽  
D J Lydiate
Keyword(s):  
Linkage Group ◽  
Brassica Juncea ◽  
Fragment Length Polymorphism ◽  
Leptosphaeria Maculans ◽  
Recessive Gene ◽  
Brassica Species ◽  
Blackleg Disease ◽  
Recessive Resistance ◽  
B Genome ◽  
Restriction Fragment Length

Blackleg disease of crucifers, caused by the fungus Leptosphaeria maculans, is a major concern to oilseed rape producers worldwide. Brassica species containing the B genome have high levels of resistance to blackleg. Brassica juncea F2 and first-backcross (B1) populations segregating for resistance to a PG2 isolate of L. maculans were created. Segregation for resistance to L. maculans in these populations suggested that resistance was controlled by two independent genes, one dominant and one recessive in nature. A map of the B. juncea genome was constructed using segregation in the F2 population of a combination of restriction fragment length polymorphism (RFLP) and microsatel lite markers. The B. juncea map consisted of 325 loci and was aligned with previous maps of the Brassica A and B genomes. The gene controlling dominant resistance to L. maculans was positioned on linkage group J13 based on segregation for resistance in the F2 population. This position was confirmed in the B1 population in which the resistance gene was definitively mapped in the interval flanked by pN199RV and sB31143F. The provisional location of the recessive gene controlling resistance to L. maculans on linkage group J18 was identified using a subset of informative F2 individuals.Key words: blackleg, B genome, phoma, recessive resistance.

Characterization of an opsin gene from the ascomycete Leptosphaeria maculans

Genome ◽  
2001 ◽  
Vol 44 (2) ◽  
pp. 167-171 ◽  
Author(s):  
Alexander Idnurm ◽  
Barbara J Howlett
Keyword(s):  
Leptosphaeria Maculans ◽  
Brassica Species ◽  
Binding Pocket ◽  
Opsin Gene ◽  
Amino Acid Residues ◽  
Blackleg Disease ◽  
Type Locus ◽  
Cloned Gene ◽  
Retinal Binding Pocket

An opsin gene (ops) has been characterized from Leptosphaeria maculans, the ascomycete that causes blackleg disease of Brassica species. This is the second opsin identified outside the archaeal and animal kingdoms. The gene encodes a predicted protein with high similarity (70.3%) and identity (53.3%) to the nop-1 opsin of another ascomycete Neurospora crassa. The L. maculans opsin also has identical amino acid residues in 20 of the 22 residues in the retinal-binding pocket of archaeal opsins. Opsin, on the fourth largest chromosome of L. maculans and 22 cM from the mating type locus, is the first cloned gene to be mapped in L. maculans. Opsin is transcribed at high levels in mycelia grown in the presence and absence of light; this pattern is in contrast with that of the N. crassa opsin, which is transcribed only in the light.Key words: opsin, Phoma lingam, Brassica napus.

Usefulness of winter canola (Brassica napus) race-specific resistance genes against blackleg (causal agent Leptosphaeria maculans) in southern Australian growing conditions

2011 ◽  
Vol 62 (2) ◽  
pp. 162 ◽  
Author(s):  
K. A. Light ◽  
N. N. Gororo ◽  
P. A. Salisbury
Keyword(s):  
Disease Resistance ◽  
Resistance Genes ◽  
Leptosphaeria Maculans ◽  
Brassica Species ◽  
Superior Performance ◽  
Adult Plant ◽  
Control Line ◽  
Blackleg Disease ◽  
Blackleg Resistance ◽  
Spring Canola

Studies on the blackleg resistance of Brassica lines containing known race-specific, Rlm resistance genes can provide information on the potential use of these genes in the genetic improvement of Australian spring canola lines. Lines of four Brassica species (winter B. napus, B. nigra, B. juncea, B. rapa) containing one or more known specific Rlm genes were assessed for seedling and adult plant survival, on infected stubble derived from crops of both polygenic and B. rapa ssp. sylvestris resistance types, to determine their potential usefulness as sources of blackleg disease resistance in diverse environments in southern Australia. Seedling and adult plant resistance of lines differed depending on the stubble type used. The seedling and adult plant blackleg resistance of several lines containing the resistance genes Rlm1, Rlm1/Rlm3, Rlm7, and Rlm10 was consistently higher than the control line, AV-Sapphire, which carries polygenic resistance. The superior performance of these lines indicates that winter B. napus and B. nigra lines have outstanding potential for improving blackleg disease resistance under Australian conditions.

Molecular mapping of QTLs conferring stay-green in grain sorghum (Sorghum bicolor L. Moench)

Genome ◽  
2000 ◽  
Vol 43 (3) ◽  
pp. 461-469 ◽  
Author(s):  
Wenwei Xu ◽  
Prasanta K Subudhi ◽  
Oswald R Crasta ◽  
Darrell T Rosenow ◽  
John E Mullet ◽  
...  
Keyword(s):  
Drought Stress ◽  
Linkage Group ◽  
Restriction Fragment Length Polymorphism ◽  
Fragment Length Polymorphism ◽  
Phenotypic Variability ◽  
Linkage Groups ◽  
Stay Green ◽  
Group A ◽  
Sorghum Bicolor L ◽  
Restriction Fragment Length

Drought resistance is of enormous importance in crop production. The identification of genetic factors involved in plant response to drought stress provides a strong foundation for improving drought tolerance. Stay-green is a drought resistance trait in sorghum (Sorghum bicolor L. Moench) that gives plants resistance to premature senescence under severe soil moisture stress during the post-flowering stage. The objective of this study was to map quantitative trait loci (QTLs) that control the stay-green and chlorophyll content in sorghum. By using a restriction fragment length polymorphism (RFLP) map, developed from a recombinant inbred line (RIL) population, we identified four stay-green QTLs, located on three linkage groups. The QTLs (Stg1 and Stg2) are on linkage group A, with the other two, Stg3 and Stg4, on linkage groups D and J, respectively. Two stay-green QTLs, Stg1 and Stg2, explaining 13-20% and 20-30% of the phenotypic variability, respectively, were consistently identified in all trials at different locations in two years. Three QTLs for chlorophyll content (Chl1, Chl2, and Chl3), explaining 25-30% of the phenotypic variability were also identified under post-flowering drought stress. All coincided with the three stay-green QTL regions (Stg1, Stg2, andStg3) accounting for 46% of the phenotypic variation. The Stg1 and Stg2 regions also contain the genes for key photosynthetic enzymes, heat shock proteins, and an abscisic acid (ABA) responsive gene. Such spatial arrangement shows that linkage group A is important for drought- and heat-stress tolerance and yield production in sorghum. High-resolution mapping and cloning of the consistent stay-green QTLs may help to develop drought-resistant hybrids and to understand the mechanism of drought-induced senescence in plants.Key words: drought tolerance, genetic mapping, post-flowering stress, restriction fragment length polymorphism.

Amphidiploid Brassica juncea contains conserved progenitor genomes

Genome ◽  
2000 ◽  
Vol 43 (4) ◽  
pp. 679-688 ◽  
Author(s):  
T Axelsson ◽  
C M Bowman ◽  
A G Sharpe ◽  
D J Lydiate ◽  
U Lagercrantz
Keyword(s):  
Genome Evolution ◽  
Fragment Length Polymorphism ◽  
Rapid Change ◽  
Linkage Maps ◽  
Diploid Progenitor ◽  
B Genome ◽  
Disomic Inheritance ◽  
Polyploid Formation ◽  
A Genome ◽  
Restriction Fragment Length

To perform a detailed study of genome evolution in the natural Brassica amphidiploid B. juncea, we have constructed two linkage maps based on RFLP (restriction fragment length polymorphism) markers; one generated from a cross between a resynthesized B. juncea (a chromosome doubled interspecific B. rapa × B. nigra hybrid) and a natural B. juncea cultivar, the other from a cross between two B. juncea cultivars. By using a common cultivar in both crosses, the two maps could be unambiguously integrated. All loci exhibited disomic inheritance of parental alleles in the natural × resynthesized cross, showing that B. rapa chromosomes paired exclusively with their A-genome homologues in B. juncea and that B. nigra chromosomes likewise paired with their B-genome homologues. The maps derived from the two crosses were also perfectly collinear. Furthermore, these maps were collinear with maps of the diploid progenitor species (B. nigra and B. rapa) produced using the same set of RFLP probes. These data indicate that the genome of B. juncea has remained essentially unchanged since polyploid formation. Our observations appear to refute the suggestion that the formation of polyploid genomes is accompanied by rapid change in genome structure.Key words: RFLP, comparative mapping, Brassica rapa, Brassica nigra, genome evolution.

Reaction of a range of Brassica species under Australian conditions to the fungus, Leptosphaeria maculans, the causal agent of blackleg

2002 ◽  
Vol 42 (5) ◽  
pp. 587 ◽  
Author(s):  
S. J. Marcroft ◽  
N. Wratten ◽  
A. Purwantara ◽  
P. A. Salisbury ◽  
T. D. Potter ◽  
...  
Keyword(s):  
Seedling Survival ◽  
Leptosphaeria Maculans ◽  
Brassica Species ◽  
Causal Agent ◽  
Adult Plant ◽  
Growth Stages ◽  
Sources Of Resistance ◽  
Breeding Programs ◽  
Resistant Species ◽  
B Genome

A range of Brassica species was screened for resistance to Leptosphaeria maculans, the causal agent of blackleg. The lines were assessed in 8 disease nurseries in 4 canola growing regions of Australia and in 1�glasshouse trial, with a view to identifying alternative sources of resistance to L. maculans for Australian breeding programs. Lines were screened for degree of internal and external blackleg symptoms during both the seedling and adult plant growth stages. Correlation for resistance with ranking between disease nurseries was very strong (0.41-0.98). Brassica carinata and B. nigra were the most resistant species in the disease nurseries, being even more resistant than B. juncea. The 7 European winter B. napus lines tested were significantly more resistant than the 7�Australian spring B. napus lines, with another crucifer, Sinapis alba, being intermediate in resistance between the European and Australian B. napus lines. The same ranking of lines from most to least resistant was also seen when cotyledons and stems were inoculated in the glasshouse with 2 well-characterised Australian isolates. With the exception of the B. napus susceptible control Westar, all lines had similar frequencies of seedling survival in the nurseries. However, mature plants of these lines varied significantly in their degree of resistance. This indicates that screening for seedling survival is not useful in selecting L. maculans resistant lines in Australia. The Brassica lines with the B genome, especially B. carinata, and the winter B. napus types are now being used as sources of resistance in Australian breeding programs.

Acantozero erucic acid oriental condiment mustard

2010 ◽  
Vol 90 (4) ◽  
pp. 499-502
Author(s):  
G. Rakow ◽  
J P Raney ◽  
D. Rode
Keyword(s):  
Erucic Acid ◽  
Brassica Juncea ◽  
Seed Oil ◽  
Seed Protein ◽  
Leptosphaeria Maculans ◽  
Glucosinolate Content ◽  
Blackleg Disease ◽  
Albugo Candida ◽  
White Rust ◽  
Cultivar Description

Acanto is the first zero erucic acid oriental condiment mustard [Brassica juncea (L.) Czern.]. It has the same grain yield, plant height, seed protein content, seed weight, allyl glucosinolate content, and seed chlorophyll content as the check cultivar Cutlass. Both cultivars are highly resistant to blackleg disease caused by Leptosphaeria maculans (Desm.) Ces et de Not., but are susceptible to white rust race 2v caused by Albugo candida (Pers.) Kuntze. Acanto is more susceptible to white rust race 2a than is Cutlass. Acanto matures 2 d later than Cutlass, has a 2.9% lower seed oil (fixed oil) content and its seed colour is a darker yellow. Acanto was well adapted to the mustard growing areas of the Canadian prairies.Key words: Brassica juncea (L.) Czern., cultivar description, zero erucic acid oil

Identification of RFLP markers linked to a gene for downy mildew resistance (Sdm) in sorghum

1996 ◽  
Vol 74 (2) ◽  
pp. 315-317 ◽  
Author(s):  
Boung-Jun Oh ◽  
Richard A. Frederiksen ◽  
Clint W. Magill
Keyword(s):  
Disease Resistance ◽  
Linkage Group ◽  
Downy Mildew ◽  
Fragment Length Polymorphism ◽  
Hybrid Breeding ◽  
Rflp Markers ◽  
Downy Mildew Resistance ◽  
Peronosclerospora Sorghi ◽  
Sorghum Accession ◽  
Restriction Fragment Length

The Sdm locus in sorghum accession SC325 confers resistance to downy mildew caused by pathotypes 1 and 3 of Peronosclerospora sorghi. Restriction fragment length polymorphism linkage analysis placed the Sdm locus near loci detected by probes pSbTXS552 and pSbTXS361 at 5.0 and 7.9 cM, respectively. Fragment patterns for the cross segregating for disease resistance differed from those for the original mapping cross, preventing assignment of Sdm to a linkage group. Keywords: Peronosclerospora sorghi, resistance, RFLP, linkage, hybrid breeding.

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