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GrainGenes Reference Report: TAG-106-1283

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Reference	TAG-106-1283
Title	QTL mapping provides evidence for lack of association of the avoidance of leaf rust in Hordeum chilense with stomata density
Journal	Theoretical and Applied Genetics
Year	2003
Volume	106
Pages	1283-1292
Author	Patto MCV [ Show all 7 ]
Abstract	Summary: In cereals, rust fungi are among the most harmful pathogens. Breeders usually rely on short-lived hypersensitivity resistance. As an alternative, 'avoidance' may be a more durable defence mechanism to protect plants to rust fungi. In Hordeum chilense avoidance is based on extensive wax covering of stomata, which interferes with the induction of appressorium formation by the rust fungi. High avoidance levels are associated with a higher stoma density on the abaxial leaf epidermis. The avoidance level was assessed as the percentage of germ tube/stoma encounters that did not result in appressorium differentiation by Puccinia hordei, the barley leaf rust fungus. One hundred F2 individuals from the cross between two H. chilense accessions with contrasting levels of avoidance showed a continuous distribution for avoidance of the rust fungus and for stoma density, indicating quantitative inheritance of the traits. No significant correlation was found between avoidance and stoma density in the segregating F2 population. In order to map quantitative trait loci (QTLs) for both traits, an improved molecular marker linkage map was constructed, based on the F2 population. The resulting linkage map spanned 620 cM and featured a total of 437 AFLP markers, thirteen RFLPs, four SCARs, nine SSRs, one STS and two seed storage protein markers. It consisted of seven long and two shorter linkage groups, and was estimated to cover 81% of the H. chilense genome. Restricted multiple interval mapping identified two QTLs for avoidance and three QTLs for stoma density in the abaxial leaf surface. The QTLs for avoidance were mapped on chromosome 3 and 5; those for stoma density on chromosomes 1, 3 and 7. Only the two QTLs regions located on chromosome 3 (one for avoidance and the other for stoma density) overlapped. The wild barley H. chilense has a high crossability with other members of the Triticeae tribe. The knowledge on the location of the QTLs responsible for the avoidance trait is a prerequisite to transfer this favourable agronomic trait from H. chilense to cultivated cereal genomes
External Databases	Pubmed: 12748780
Keyword	[ Hide all but 1 of 66 ] accessions aflp aflp marker appressoria appressorium appressorium differentiation appressorium formation avoidance barley barley leaf rust barley leaves cereal genomes cover cross crossability densities density differentiation epidermis fungi fungus genetic linkage map hordei hordeum induction inheritance interval interval mapping leaf rust linkage linkage groups linkage map locus map mapping mechanism member mendelian factors molecular marker morphology multiple percentage population protein provides qtl qtl mapping quantitative quantitative trait quantitative trait loci resistance rust seed seed storage protein stoma density stomata storage storage protein sts surface trait trait loci transfer triticeae wild wild barley

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