Gene sequences of vromindolines in Avena species

Abstract

Vromindolines, a family of oat starch-bound proteins responsible for the extremely soft endosperm of this cereal, are characterized by a tryptophan-rich domain and ten conserved cysteine residues, as it was observed in the starch-bound proteins from other cereals, and proved to be specific of the genus Avena. Two-dimensional electrophoresis of vromindolines from different oat species, both cultivated and wild, revealed that they are present in all genomes and ploidy levels, with no major differences in their molecular weight and electrophoretic mobility. PCR amplification and sequencing of genes coding for VIN-2 and VIN-3 indicated that both proteins are strongly conserved across the species analysed. Some differences were found between diploid and polyploid accessions at specific amino acid positions along the protein. In particular the C-genome accessions (A. clauda, A. eriantha, A. ventricosa) differed from the A-genome diploids (A. canariensis, A. damascena, A. longiglumis, A. nuda, A. strigosa) for some peculiar sequences. Tetraploids (A. barbata, A. magna and A. insularis) showed two sequences each for both proteins; the variability observed in them was similar to that found in A. sativa. The characteristics of these genes could help to clarify the genetic relationship among the various species of the genus Avena. Moreover, the knowledge of the genetic control of these proteins represent an important tool for the modulation of oat endosperm texture.