title: A splice acceptor site mutation in TaGW2-A1 increases thousand grain weight in tetraploid and hexaploid wheat through wider and longer grains.
abstract: Across 13 experiments the gw2 - A1 mutant allele shifts grain size distribution consistently across all grains significantly increasing grain weight (6.6 %), width (2.8 %) and length (2.1 %) in tetraploid and hexaploid wheat. There is an urgent need to identify, understand and incorporate alleles that benefit yield in polyploid wheat. The rice OsGW2 gene functions as a negative regulator of grain weight and width and is homologous to the wheat TaGW2 gene. Previously it was shown that transcript levels of the A-genome homoeologue, TaGW2-A1, are negatively associated with grain width in hexaploid wheat. In this study we screened the tetraploid Kronos TILLING population to identify mutants in TaGW2-A1. We identified a G to A transition in the splice acceptor site of exon 5 which leads to mis-splicing in TaGW2-A1. We backcrossed the mutant allele into tetraploid and hexaploid wheat and generated a series of backcross derived isogenic lines which were evaluated in glasshouse and field conditions. Across 13 experiments the GW2-A1 mutant allele significantly increased thousand grain weight (6.6 %), grain width (2.8 %) and grain length (2.1 %) in tetraploid and hexaploid wheat compared to the wild type allele. In hexaploid wheat, this led to an increase in spike yield since no differences were detected for spikelet or grain number between isogenic lines. The increase in grain width and length was consistent across grains of different sizes, suggesting that the effect of the mutation is stable across the ear and within spikelets. Differences in carpel size and weight between alleles were identified as early as 5 days before anthesis, suggesting that TaGW2-A1 acts on maternal tissue before anthesis to restrict seed size. A single nucleotide polymorphism marker was developed to aid the deployment of the mutant allele into breeding programmes.
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
authors.forename: James
authors.initials: J
authors.lastname: Simmonds
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Scott
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
authors.forename: Jemima
authors.initials: J
authors.lastname: Brinton
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.|CEBAS-CSIC, Espinardo, P.O. Box 164, 30100, Murcia, Spain.
authors.forename: Teresa C
authors.initials: TC
authors.lastname: Mestre
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
authors.forename: Max
authors.initials: M
authors.lastname: Bush
authors.affiliation: University of California Davis, One Shields Avenue, Davis, CA, 95616, USA.
authors.forename: Alicia
authors.initials: A
authors.lastname: Del Blanco
authors.affiliation: University of California Davis, One Shields Avenue, Davis, CA, 95616, USA.|Howard Hughes Medical Institute, Chevy Chase, MD, 20815, USA.
authors.forename: Jorge
authors.initials: J
authors.lastname: Dubcovsky
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK. cristobal.uauy@jic.ac.uk.
authors.forename: Cristobal
authors.identifier: http://orcid.org/0000-0002-9814-1770
authors.initials: C
authors.lastname: Uauy
mesh_terms: D000483:Alleles; D018744:DNA, Plant / Q000235:genetics; D002523:Edible Grain / Q000235:genetics; D005091:Exons; D017343:Genes, Plant; D009154:Mutation; D010641:Phenotype; D000069600:Plant Breeding; D010940:Plant Proteins / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D011123:Polyploidy; D022821:RNA Splice Sites; D014908:Triticum / Q000235:genetics*
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D022821:RNA Splice Sites