Variation in genome composition of blue-aleurone wheat

Abstract

Different blue-aleurone wheats display major differences in chromosome composition, ranging from disomic chromosome additions, substitutions, single chromosome arm introgressions and chromosome translocation of Thinopyrum ponticum. Anthocyanins are of great importance for human health due to their antioxidant, anti-inflammatory, anti-microbial and anti-cancerogenic potential. In common wheat (Triticum aestivum L.) their content is low. However, elite lines with blue aleurone exhibit significantly increased levels of anthocyanins. These lines carry introgressed chromatin from wild relatives of wheat such as Thinopyrum ponticum and Triticum monococcum. The aim of our study was to characterize genomic constitutions of wheat lines with blue aleurone using genomic and fluorescence in situ hybridization. We used total genomic DNA of Th. ponticum and two repetitive DNA sequences (GAA repeat and the Afa family) as probes to identify individual chromosomes. This enabled precise localization of introgressed Th. ponticum chromatin. Our results revealed large variation in chromosome constitutions of the blue-aleurone wheats. Of 26 analyzed lines, 17 carried an introgression from Th. ponticum; the remaining nine lines presumably carry T. monococcum chromatin undetectable by the methods employed. Of the Th. ponticum introgressions, six different types were present, ranging from a ditelosomic addition (cv. Blue Norco) to a disomic substitution (cv. Blue Baart), substitution of complete (homologous) chromosome arms (line UC66049) and various translocations of distal parts of a chromosome arm(s). Different types of introgressions present support a hypothesis that the introgressions activate the blue aleurone trait present, but inactivated, in common wheat germplasm.