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GrainGenes Reference Report: JEB-56-47

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Reference	JEB-56-47
Title	A centromeric region on chromosome 6(6H) affects dormancy in an induced mutant in barley
Journal	Journal of Experimental Botany
Year	2005
Volume	56
Pages	47-54
Author	Prada D Romagosa I Ullrich SE Molina-Cano JL
Abstract	Genetic control of seed dormancy in barley ( Hordeum vulgare L.) has mostly been described in terms of quantitative variation. Although some molecular markers for dormancy QTL have been identified, the corresponding genes involved in the regulation of the process have not been cloned. Induced barley mutants may constitute useful material to study the physiology and genetics of seed dormancy. The objective of this study was to identify the genetic control of this trait in a mutant (TL43) produced in the barley cv. Triumph. This mutant was selected for reduced dormancy and reduced sensitivity to abscisic acid (ABA). Two sets of F SUB 6 barley lines were selected for high and low levels of dormancy from a cross between the original dormant parent and the sodium azide-induced non-dormant TL43 mutant. Unexpectedly, given the near-isogenic nature of these two genotypes, polymorphism was detected for an SSR located in the centromeric region of chromosome 6(6H) out of a total of 92 molecular markers evenly distributed along the genome. Fortunately, upon three cycles of intensive divergent selection, every dormant and non-dormant F SUB 5 line consistently showed the genotype for this region identical to Triumph and TL43, respectively. Based on the mutagenic effect presumably attributed to sodium azide, mostly single point mutations, it cannot be clearly established if such extensive genomic variation on chromosome 6(6H) is due to the mutagenic treatment or may be an introgression from an unknown source. The means that could originate such heterogeneity are discussed; however, regardless of its origin, this genomic region shows a strong association with the expression of seed dormancy and provides an additional genetic locus for further studies of the mechanistic basis of this complex trait. In addition, since TL43 shows reduced sensitivity to ABA, the response to this hormone was determined on the F SUB 6 seed from the two sets of selected F SUB 5 lines. The results confirmed that the initial level of dormancy in the seed lot is the most important factor in determining ABA sensitivity
External Databases	Pubmed: 15501909
Keyword	[ Hide all but 1 of 36 ] abscisic acid barley centromeres chromosomes control crosses dormancy gene genes genetic control genetic markers genetic polymorphism genetic regulation genetics genome genome analysis genotype genotypes heterogeneity hordeum vulgare induced mutations introgression lines loci molecular marker mutagenesis mutants mutations origin polymorphism regulation seed dormancy seeddormancy selection sodium sodium azide

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