Molecular Characterization of the Cytoplasmic Male Sterility System Underlying the Breeding and Production of HyvidoTM Hybrids in Barley

Barley (Hordeum vulgare) ranks amongst the most important small grain cereals grown worldwide and its crop finds use in both food and feed applications. Despite its predominant position in modern agriculture, a reliable and competitive hybridization system has only lately become available. Recent years have seen the market introduction of hybrid cultivars for winter barley based on the cytoplasmic male sterility (CMS) system described by Ahokas (Ahokas, 1979). Both the cytoplasm and the restorer locus Rfm1 were originally derived from wild barley (Hordeum vulgare ssp. spontaneum) accessions that were used as donor for the introduction of the CMS system into cultivated barley. In practice, this hybridization system proved sufficiently reliable to convert a strictly autogamous species like barley into a hybrid crop relying on wind pollination only and allowed for the commercialization of high-yielding hybrids.

Because of its diploid genome, barley is considered a model crop for the Triticeae tribe that comprises many polyploid crops including wheat. In the past years, valuable genomic tools have become available in barley, paving the way for map-based cloning projects. In parallel, the development of non-gridded BAC libraries has facilitated the access to genetic loci in genotypes of interest in addition to the Morex reference sequence.

With the help of the available genomic resources, we here describe the molecular characterization of the CMS hybridization system in barley and its application in the breeding and production of commercial hybrids.