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Association mapping of spot blotch resistance in wild barley.

Roy JK, Smith KP, Muehlbauer GJ, Chao S, Close TJ, Steffenson BJ - Mol. Breed. (2010)

Bottom Line: A high frequency of resistance was found in the WBDC as 95% (302/318) of the accessions exhibited low infection responses.These QTL were found on chromosomes 1H, 2H, 3H, 5H, and 7H and explained from 2.3 to 3.9% of the phenotypic variance.This study demonstrates that AM is an effective technique for identifying and mapping QTL for disease resistance in a wild crop progenitor.

View Article: PubMed Central - PubMed

ABSTRACT
Spot blotch, caused by Cochliobolus sativus, is an important foliar disease of barley. The disease has been controlled for over 40 years through the deployment of cultivars with durable resistance derived from the line NDB112. Pathotypes of C. sativus with virulence for the NDB112 resistance have been detected in Canada; thus, many commercial cultivars are vulnerable to spot blotch epidemics. To increase the diversity of spot blotch resistance in cultivated barley, we evaluated 318 diverse wild barley accessions comprising the Wild Barley Diversity Collection (WBDC) for reaction to C. sativus at the seedling stage and utilized an association mapping (AM) approach to identify and map resistance loci. A high frequency of resistance was found in the WBDC as 95% (302/318) of the accessions exhibited low infection responses. The WBDC was genotyped with 558 Diversity Array Technology (DArT((R))) and 2,878 single nucleotide polymorphism (SNP) markers and subjected to structure analysis before running the AM procedure. Thirteen QTL for spot blotch resistance were identified with DArT and SNP markers. These QTL were found on chromosomes 1H, 2H, 3H, 5H, and 7H and explained from 2.3 to 3.9% of the phenotypic variance. Nearly half of the identified QTL mapped to chromosome bins where spot blotch resistance loci were previously reported, offering some validation for the AM approach. The other QTL mapped to unique genomic regions and may represent new spot blotch resistance loci. This study demonstrates that AM is an effective technique for identifying and mapping QTL for disease resistance in a wild crop progenitor. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11032-010-9402-8) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus

Two consensus maps of arbitrarily selected DArT® (left) and SNP markers (right) for the seven barley chromosomes: 1H–7H. Positions of DArT markers and associated bins were according to Wenzl et al. (2006), and those for SNP markers and associated bins were according to Close et al. (2009). Between the representative DArT and SNP chromosomal maps, the bin numbers of Kleinhofs and Graner (2001) are indicated by the prefix ‘B’. The bolded black marker names indicate loci associated with spot blotch resistance at P = 0.05 after correction for multiple comparisons in the Wild Barley Diversity Collection (WBDC). Vertical solid black bars along the chromosomes indicate the regions or bins where previously reported spot blotch resistance genes or QTLs were identified in biparental mapping populations that did not involve a wild barley parent. Vertical open bars along the chromosomes indicate the regions or bins where previously reported spot blotch resistance genes or QTLs were identified in biparental mapping populations that included a wild barley parent. A centiMorgan scale is given at the left side
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Fig2: Two consensus maps of arbitrarily selected DArT® (left) and SNP markers (right) for the seven barley chromosomes: 1H–7H. Positions of DArT markers and associated bins were according to Wenzl et al. (2006), and those for SNP markers and associated bins were according to Close et al. (2009). Between the representative DArT and SNP chromosomal maps, the bin numbers of Kleinhofs and Graner (2001) are indicated by the prefix ‘B’. The bolded black marker names indicate loci associated with spot blotch resistance at P = 0.05 after correction for multiple comparisons in the Wild Barley Diversity Collection (WBDC). Vertical solid black bars along the chromosomes indicate the regions or bins where previously reported spot blotch resistance genes or QTLs were identified in biparental mapping populations that did not involve a wild barley parent. Vertical open bars along the chromosomes indicate the regions or bins where previously reported spot blotch resistance genes or QTLs were identified in biparental mapping populations that included a wild barley parent. A centiMorgan scale is given at the left side

Mentions: From the AM analysis with DArT markers after correction for multiple comparisons, five QTL conferring resistance to spot blotch were identified at a significance level of P ≤ 0.05 (Table 1; Fig. 2). Two QTL (Rcs-qtl-1H-bPb-2813 and Rcs-qtl-1H-bPb-3089) were identified on chromosome 1H and explained 2.7 and 3.9% of the phenotypic variation as assessed by R2, respectively. The remaining three QTL were identified on chromosomes 3H (Rcs-qtl-3H-bPb-1068), 5H (Rcs-qtl-5H-bPb-2378), and 7H (Rcs-qtl-7H-bPb-4584) and explained 3.6, 3.6, and 3.1% of the phenotypic variation, respectively. Of the five QTL identified in this analysis, three mapped to bins where spot blotch resistance loci were previously reported and two mapped to novel locations (Table 1; Fig. 2). The MAF of DArT markers showing associations with spot blotch resistance ranged from 0.16 (bPb-2378 on chromosome 5H) to 0.40 (bPb-1068 on chromosome 3H).Table 1


Association mapping of spot blotch resistance in wild barley.

Roy JK, Smith KP, Muehlbauer GJ, Chao S, Close TJ, Steffenson BJ - Mol. Breed. (2010)

Two consensus maps of arbitrarily selected DArT® (left) and SNP markers (right) for the seven barley chromosomes: 1H–7H. Positions of DArT markers and associated bins were according to Wenzl et al. (2006), and those for SNP markers and associated bins were according to Close et al. (2009). Between the representative DArT and SNP chromosomal maps, the bin numbers of Kleinhofs and Graner (2001) are indicated by the prefix ‘B’. The bolded black marker names indicate loci associated with spot blotch resistance at P = 0.05 after correction for multiple comparisons in the Wild Barley Diversity Collection (WBDC). Vertical solid black bars along the chromosomes indicate the regions or bins where previously reported spot blotch resistance genes or QTLs were identified in biparental mapping populations that did not involve a wild barley parent. Vertical open bars along the chromosomes indicate the regions or bins where previously reported spot blotch resistance genes or QTLs were identified in biparental mapping populations that included a wild barley parent. A centiMorgan scale is given at the left side
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908432&req=5

Fig2: Two consensus maps of arbitrarily selected DArT® (left) and SNP markers (right) for the seven barley chromosomes: 1H–7H. Positions of DArT markers and associated bins were according to Wenzl et al. (2006), and those for SNP markers and associated bins were according to Close et al. (2009). Between the representative DArT and SNP chromosomal maps, the bin numbers of Kleinhofs and Graner (2001) are indicated by the prefix ‘B’. The bolded black marker names indicate loci associated with spot blotch resistance at P = 0.05 after correction for multiple comparisons in the Wild Barley Diversity Collection (WBDC). Vertical solid black bars along the chromosomes indicate the regions or bins where previously reported spot blotch resistance genes or QTLs were identified in biparental mapping populations that did not involve a wild barley parent. Vertical open bars along the chromosomes indicate the regions or bins where previously reported spot blotch resistance genes or QTLs were identified in biparental mapping populations that included a wild barley parent. A centiMorgan scale is given at the left side
Mentions: From the AM analysis with DArT markers after correction for multiple comparisons, five QTL conferring resistance to spot blotch were identified at a significance level of P ≤ 0.05 (Table 1; Fig. 2). Two QTL (Rcs-qtl-1H-bPb-2813 and Rcs-qtl-1H-bPb-3089) were identified on chromosome 1H and explained 2.7 and 3.9% of the phenotypic variation as assessed by R2, respectively. The remaining three QTL were identified on chromosomes 3H (Rcs-qtl-3H-bPb-1068), 5H (Rcs-qtl-5H-bPb-2378), and 7H (Rcs-qtl-7H-bPb-4584) and explained 3.6, 3.6, and 3.1% of the phenotypic variation, respectively. Of the five QTL identified in this analysis, three mapped to bins where spot blotch resistance loci were previously reported and two mapped to novel locations (Table 1; Fig. 2). The MAF of DArT markers showing associations with spot blotch resistance ranged from 0.16 (bPb-2378 on chromosome 5H) to 0.40 (bPb-1068 on chromosome 3H).Table 1

Bottom Line: A high frequency of resistance was found in the WBDC as 95% (302/318) of the accessions exhibited low infection responses.These QTL were found on chromosomes 1H, 2H, 3H, 5H, and 7H and explained from 2.3 to 3.9% of the phenotypic variance.This study demonstrates that AM is an effective technique for identifying and mapping QTL for disease resistance in a wild crop progenitor.

View Article: PubMed Central - PubMed

ABSTRACT
Spot blotch, caused by Cochliobolus sativus, is an important foliar disease of barley. The disease has been controlled for over 40 years through the deployment of cultivars with durable resistance derived from the line NDB112. Pathotypes of C. sativus with virulence for the NDB112 resistance have been detected in Canada; thus, many commercial cultivars are vulnerable to spot blotch epidemics. To increase the diversity of spot blotch resistance in cultivated barley, we evaluated 318 diverse wild barley accessions comprising the Wild Barley Diversity Collection (WBDC) for reaction to C. sativus at the seedling stage and utilized an association mapping (AM) approach to identify and map resistance loci. A high frequency of resistance was found in the WBDC as 95% (302/318) of the accessions exhibited low infection responses. The WBDC was genotyped with 558 Diversity Array Technology (DArT((R))) and 2,878 single nucleotide polymorphism (SNP) markers and subjected to structure analysis before running the AM procedure. Thirteen QTL for spot blotch resistance were identified with DArT and SNP markers. These QTL were found on chromosomes 1H, 2H, 3H, 5H, and 7H and explained from 2.3 to 3.9% of the phenotypic variance. Nearly half of the identified QTL mapped to chromosome bins where spot blotch resistance loci were previously reported, offering some validation for the AM approach. The other QTL mapped to unique genomic regions and may represent new spot blotch resistance loci. This study demonstrates that AM is an effective technique for identifying and mapping QTL for disease resistance in a wild crop progenitor. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11032-010-9402-8) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus