Mutations in the gene of the G\u03b1 subunit of the heterotrimeric G protein are the cause for the brachytic1 semi-dwarf phenotype in barley and applicable for practical breeding

Ilka Braumann,Shakhira Zakhrabekova,Nils Stein,Finn Lok,Mats Hansson,Christoph Dockter,Ruonan Zhou,Udda Lundqvist,Birgitte Skadhauge,Sebastian Beier,Axel Himmelbach

doi:10.1186/s41065-017-0045-1

Ilka Braumann, Shakhira Zakhrabekova + Show 9 more

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https://doi.org/10.1186/s41065-017-0045-1

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Abstract

BackgroundShort-culm mutants have been widely used in breeding programs to increase lodging resistance. In barley (Hordeum vulgare L.), several hundreds of short-culm mutants have been isolated over the years. The objective of the present study was to identify the Brachytic1 (Brh1) semi-dwarfing gene and to test its effect on yield and malting quality.ResultsDouble-haploid lines generated through a cross between a brh1.a mutant and the European elite malting cultivar Quench, showed good malting quality but a decrease in yield. Especially the activities of the starch degrading enzymes β-amylase and free limit dextrinase were high. A syntenic approach comparing markers in barley to those in rice (Oryza sativa L.), sorghum (Sorghum bicolor Moench) and brachypodium (Brachypodium distachyon P. Beauv) helped us to identify Brh1 as an orthologue of rice D1 encoding the Gα subunit of a heterotrimeric G protein. We demonstrated that Brh1 is allelic to Ari-m. Sixteen different mutant alleles were described at the DNA level.ConclusionsMutants in the Brh1 locus are deficient in the Gα subunit of a heterotrimeric G protein, which shows that heterotrimeric G proteins are important regulators of culm length in barley. Mutant alleles do not have any major negative effects on malting quality.

Highlights

Short-culm mutants have been widely used in breeding programs to increase lodging resistance
It is not surprising that successful “Green revolution” semi-dwarfing genes can be exemplified by Reduced height1 (Rht1) in wheat encoding a transcriptional regulator with a DELLA domain involved in gibberellic acid (GA) signaling [23], Semi-dwarf1 (Sd1) in rice [3, 28] and Sdw1 in barley [36] both deficient in a gibberellin 20-oxidase of the GA biosynthetic pathway, and Uzu1 in barley encoding the brassinosteroid receptor [7, 9]
We show that Brh1 encodes a subunit of a heterotrimeric G protein and mutant alleles of Brh1 do not have any major negative effects on malting quality

Summary

Introduction

Short-culm mutants have been widely used in breeding programs to increase lodging resistance. In barley (Hordeum vulgare L.), several hundreds of short-culm mutants have been isolated over the years. Due to the potential agronomic usefulness, many different types of semidwarf mutants have been identified in barley (Hordeum vulgare) during the last 70 years. These semi-dwarf mutants have obtained different names since they often have other pleiotropic characters which might have been in focus of the involved research group. It is not surprising that successful “Green revolution” semi-dwarfing genes can be exemplified by Reduced height (Rht1) in wheat encoding a transcriptional regulator with a DELLA domain involved in GA signaling [23], Semi-dwarf (Sd1) in rice [3, 28] and Sdw in barley [36] both deficient in a gibberellin 20-oxidase of the GA biosynthetic pathway, and Uzu in barley encoding the brassinosteroid receptor [7, 9]

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