Identification of a hard kernel texture line of synthetic allohexaploid wheat reducing the puroindoline accumulation on the D genome from Aegilops tauschii

Abstract

Grain hardness is an important factor for wheat breeding. Generally, the grain hardness of hexaploid wheat is determined by two puroindoline (PIN) genes, Pina-D1 and Pinb-D1, at the Hardness locus on chromosome 5D. Here, the grain hardness of 55 synthetic wheat lines from crosses between a durum wheat cultivar and 55 Ae. tauschii accessions were examined, and nucleotide sequence variation in Pina-Dtau1 and Pinb-Dtau1 was analyzed using the Ae. tauschii accessions. Most synthetic wheat lines showed a soft texture with smoothly rounded starch granules, whereas one exceptional line exhibited a hard texture with starch granules that tightly adhered to the matrix proteins and reduced PINA and PINB protein accumulation. The parental Ae. tauschii accession of the hard-textured synthetic line has smoothly rounded starch granules and abundant PIN accumulation in the endosperm. Any genetic change that occurred at the Pin loci was transmitted from the parental Ae. tauschii accession, but the Pina and Pinb transcription was decreased in the hard-textured synthetic line. Therefore, any genetic and/or epigenetic modification in the process of allopolyploidization might have affected the PIN accumulation in synthetic hexaploid wheat lines.