Expression level of a gibberellin 20-oxidase gene is associated with multiple agronomic and quality traits in barley
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The use of dwarfing genes has resulted in the most significant improvements in yield and adaptation in cereal crops. The allelic dwarfing gene sdw1/denso has been used throughout the world to develop commercial barley varieties. The sdw1 gene has never been used successfully for malting barley, but only for a large number of feed varieties. One of the gibberellin 20-oxidase genes (Hv20ox 2 ) was identified as the candidate gene for sdw1/denso. Semi-quantitative real-time RT-PCR revealed that Hv20ox 2 was expressed at different levels in various organs of barley. Transcriptional levels were reduced in leaf blade, sheath, stem and rachis tissue in the barley variety Baudin with the denso gene. Subsequently, the relative expression levels of Hv20ox 2 were determined by quantitative real-time RT-PCR in a doubled haploid population and mapped as a quantitative trait. A single expression quantitative trait locus (eQTL) was identified and mapped to its structural gene region on chromosome 3H. The eQTL was co-located with QTLs for yield, height, development score, hectolitre weight and grain plumpness. The expression level of Hv20ox 2 was reduced fourfold in the denso mutant, but around 60-fold in the sdw1 mutant, compared to the control variety. The reduced expression level of Hv20ox 2 enhanced grain yield by increasing the number of effective tillers, but had negative effects on grain and malting quality. The sdw1 gene can be used only in feed barley due to its severe reduction of Hv20ox 2 expression. The gene expression marker for Hv20ox 2 can be used to distinguish different alleles of sdw1/denso.
KeywordsQuantitative Trait Locus Doubled Haploid Agronomic Trait Doubled Haploid Line Barley Variety
This project is supported by the Grain Research & Development Corporation of Australia, earmarked fund for Modern Agro-industry Technology Research System of China, Major International Scientific and Technological Joint Research Program of Zhejiang (2008C14072), National Natural Science Foundation of China (30828023 & 30800686) and Zhejiang Natural Science Foundation (Y308495).
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