Identification of RFLP markers linked to the white rust resistance gene (Acr) in mustard (Brassica juncea (L.) Czern. and Coss.)

Genome ◽  
1998 ◽  
Vol 41 (4) ◽  
pp. 626-628 ◽  
Author(s):  
W Y Cheung ◽  
R K Gugel ◽  
B S Landry

White rust and staghead, caused by Albugo candida, is an economically important disease of Brassica juncea and Brassica rapa crops in western Canada. The identification of genes for white rust resistance in these crops and the development of molecular markers for these genes will allow the rapid identification of resistant germplasm and should accelerate the development of white rust resistant cultivars. In this study, 119 F1-derived doubled-haploid progeny lines of a cross between white rust susceptible (J90-4317) and white rust resistant (J90-2733) B. juncea lines were evaluated for resistance to A. candida race 2. A single gene (Acr) responsible for conferring resistance to this pathogen was mapped on a densely populated B. juncea RFLP map developed earlier. A cosegregating RFLP marker (X140a) and two other closely linked RFLP markers (X42 and X83) were identified; the latter two markers were 2.3 and 4 cM from the Acr locus, respectively. These markers may be useful for marker-assisted selection and map-based cloning of this gene.Key words: Brassica juncea, mustard, Albugo candida, white rust, disease resistance, RFLP.

1988 ◽  
Vol 68 (2) ◽  
pp. 297-300 ◽  
Author(s):  
A. S. TIWARI ◽  
G. A. PETRIE ◽  
R. K. DOWNEY

The inheritance of resistance to white rust (Albugo Candida) race 2 in mustard (Brassica juncea) was studied in crosses involving one resistant and two susceptible cultivars. Inoculations were made in a growth chamber followed by growth of the plants under greenhouse conditions. The reaction of the F1 was like the resistant parent, indicating that resistance is dominant and controlled by nuclear genes. Backcrosses of F1 plants to the resistant parent showed the same reactions as that of the resistant parent. Backcrosses of F1 to the susceptible parents segregated in a 1:1 ratio of resistant to susceptible. The F2 segregation of resistant and susceptible plants gave a good fit to a 3:1 ratio. The study revealed that resistance is monogenic and could be easily transferred to adapted susceptible genotypes via backcrossing.Key words: Brassica juncea, Albugo Candida, mustard, white rust


Genome ◽  
2002 ◽  
Vol 45 (1) ◽  
pp. 22-27 ◽  
Author(s):  
C Kole ◽  
P H Williams ◽  
S R Rimmer ◽  
T C Osborn

Genes for resistance to white rust (Albugo candida) in oilseed Brassica rapa were mapped using a recombinant inbred (RI) population and a genetic linkage map consisting of 144 restriction fragment length polymorphism (RFLP) markers and 3 phenotypic markers. Young seedlings were evaluated by inoculating cotyledons with A. candida race 2 (AC2) and race 7 (AC7) and scoring the interaction phenotype (IP) on a 0–9 scale. The IP of each line was nearly identical for the two races and the population showed bimodal distributions, suggesting that a single major gene (or tightly linked genes) controlled resistance to the two races. The IP scores were converted to categorical resistant and susceptible scores, and these data were used to map a single Mendelian gene controlling resistance to both races on linkage group 4 where resistance to race 2 had been mapped previously. A quantitative trait loci (QTL) mapping approach using the IP scores detected the same major resistance locus for both races, plus a second minor QTL effect for AC2 on linkage group 2. These results indicate that either a dominant allele at a single locus (Aca1) or two tightly linked loci control seedling resistance to both races of white rust in the biennial turnip rape cultivar Per. The map positions of white rust resistance genes in B. rapa and Brassica napus were compared and the results indicate where additional loci that have not been mapped may be located. Alignment of these maps to the physical map of the Arabidopsis genome identified regions to target for comparative fine mapping using this model organism.Key words: plant disease, oilseed Brassica, molecular markers.


2007 ◽  
Vol 58 (3) ◽  
pp. 259 ◽  
Author(s):  
C. X. Li ◽  
K. Sivasithamparam ◽  
G. Walton ◽  
P. Salisbury ◽  
W. Burton ◽  
...  

White rust (Albugo candida) is a highly destructive disease of oilseed Brassicas such as Brassica juncea and B. rapa. Most commercial B. juncea or B. rapa varieties are highly susceptible and yield losses from combined infection of leaves and inflorescences can be up to 20% or 60% in Australia and India, respectively. In Australia, canola-quality B. juncea has been developed to extend oilseed Brassica production into lower rainfall areas, with the first commercial B. juncea canola-quality variety planned for release in 2006. It is essential to identify useful sources of host resistance in B. juncea as breeding and/or selection of material for resistance is the most cost-effective method of delivering control for farmers. Three experiments were undertaken under controlled-environmental conditions to identify the best methods of characterising host resistance and to identify sources of resistance in B. juncea germplasm from Australia, China, and India. Forty-four B. juncea genotypes, viz. 22 from India, 12 from Australia, and 10 from China, were tested. Four Chinese genotypes (CBJ-001, CBJ-002, CBJ-003, CBJ-004) and one Australian genotype (JR049) consistently showed high resistance to A. candida across the different plant growth stages against a pathotype prevailing in Australia. Similarly, the most susceptible genotypes (viz. Indian genotypes RH781, RL1359, RH819) were extremely susceptible irrespective of the plant growth stage. Overall, although disease severity on cotyledons and leaves at the different growth stages was significantly and positively correlated, there was, however, no significant correlation between the number of stagheads and any of the other disease parameters measured. Our study demonstrates that controlled-environmental conditions are suitable for rapid identification of resistant genotypes and that genotypes with high levels of resistance can be reliably identified at the cotyledonary, seedling, or flowering stages.


2019 ◽  
Vol 132 (8) ◽  
pp. 2223-2236 ◽  
Author(s):  
Heena Arora ◽  
K. Lakshmi Padmaja ◽  
Kumar Paritosh ◽  
Nitika Mukhi ◽  
A. K. Tewari ◽  
...  

2004 ◽  
Vol 17 (7) ◽  
pp. 711-719 ◽  
Author(s):  
Mohammad H. Borhan ◽  
Eric B. Holub ◽  
Jim L. Beynon ◽  
Kevin Rozwadowski ◽  
S. Roger Rimmer

Resistance to Albugo candida isolate Acem1 is conferred by a dominant gene, RAC1, in accession Ksk-1 of Arabidopsis thaliana. This gene was isolated by positional cloning and is a member of the Drosophila toll and mammalian interleukin-1 receptor (TIR) nucleotide-binding site leucine-rich repeat (NB-LRR) class of plant resistance genes. Strong identity of the TIR and NB domains was observed between the predicted proteins encoded by the Ksk-1 allele and the allele from an Acem1-susceptible accession Columbia (Col) (99 and 98%, respectively). However, major differences between the two predicted proteins occur within the LRR domain and mainly are confined to the β-strand/β-turn structure of the LRR. Both proteins contain 14 imperfect repeats. RAC1-mediated resistance was analyzed further using mutations in defense regulation, including: pad4-1, eds1-1, and NahG, in the presence of the RAC1 allele from Ksk-1. White rust resistance was completely abolished by eds1-1 but was not affected by either pad4-1 or NahG.


2008 ◽  
Vol 21 (6) ◽  
pp. 757-768 ◽  
Author(s):  
M. Hossein Borhan ◽  
Nick Gunn ◽  
Abigail Cooper ◽  
Sigrun Gulden ◽  
Mahmut Tör ◽  
...  

White blister rust in the Brassicaceae is emerging as a superb model for exploring how plant biodiversity has channeled speciation of biotrophic parasites. The causal agents of white rust across a wide breadth of cruciferous hosts currently are named as variants of a single oomycete species, Albugo candida. The most notable examples include a major group of physiological races that each are economically destructive in a different vegetable or oilseed crop of Brassica juncea (A. candida race 2), B. rapa (race 7), or B. oleracea (race 9); or parasitic on wild crucifers such as Capsella bursa-pastoris (race 4). Arabidopsis thaliana is innately immune to these races of A. candida under natural conditions; however, it commonly hosts its own molecularly distinct subspecies of A. candida (A. candida subsp. arabidopsis). In the laboratory, we have identified several accessions of Arabidopsis thaliana (e.g.,. Ws-3) that can permit varying degrees of rust development following inoculation with A. candida races 2, 4, and 7, whereas race 9 is universally incompatible in Arabidopsis thaliana and nonrusting resistance is the most prevalent outcome of interactions with the other races. Subtle variation in resistance phenotypes is evident, observed initially with an isolate of A. candida race 4, indicating additional genetic variation. Therefore, we used the race 4 isolate for map-based cloning of the first of many expected white rust resistance (WRR) genes. This gene was designated WRR4 and encodes a cytoplasmic toll-interleukin receptor-like nucleotide-binding leucine-rich repeat receptor-like protein that confers a dominant, broad-spectrum white rust resistance in the Arabidopsis thaliana accession Columbia to representative isolates of A. candida races 2, 4, 7, and 9, as verified by transgenic expression of the Columbia allele in Ws-3. The WRR4 protein requires functional expression of the lipase-like protein EDS1 but not the paralogous protein PAD4, and confers full immunity that masks an underlying nonhypersensitive incompatibility in Columbia to A. candida race 4. This residual incompatibility is independent of functional EDS1.


2015 ◽  
Vol 95 (5) ◽  
pp. 939-945 ◽  
Author(s):  
Binay K. Singh ◽  
Divakar Nandan ◽  
Supriya Ambawat ◽  
Bhagirath Ram ◽  
Arun Kumar ◽  
...  

Singh, B. K., Nandan, D., Supriya, A., Ram, B., Kumar, A., Singh, T., Meena, H. S., Kumar, V., Singh, V. V., Rai, P. K. and Singh, D. 2015. Validation of molecular markers for marker-assisted pyramiding of white rust resistance loci in Indian Mustard (Brassica juncea L.). Can. J. Plant Sci. 95: 939–945. Successful application of molecular markers in marker-assisted pyramiding relies on effective determination of the target phenotype. In this respect, evaluation of the efficiency of markers for marker-assisted selection through cross-validation in different genetic backgrounds and in different populations is a crucial step. In the present study, the previously identified Arabidopsis-derived intron polymorphic (IP) markers At5g41560 and At2g36360, which were highly linked with AcB1-A4.1 and AcB1-A5.1, respectively, were validated in a set of 25 genotypes of Indian Mustard and in three different F2 populations. The relationships between the variation of PCR products of the two markers with the percent disease index (PDI) of the tested genotypes, and the co-segregation analysis of the markers with disease phenotype in F2 populations clearly indicated that At5g41560 and At2g36360 are genotype-nonspecific markers and are closely linked to white rust resistance loci AcB1-A4.1 and AcB1-A5.1, respectively. It also became evident from the present study that AcB1-A4.1 and an another white rust resistance locus Ac(2)t are likely the same gene locus.


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