Effective Pollen-Fertility Restoration Is the Basis of Hybrid Rye Production and Ergot Mitigation.

Hybrid rye breeding leads to considerably higher grain yield and a higher revenue to the farmer. The basis of hybrid seed production is the CMS-inducing Pampa (P) cytoplasm derived from an Argentinean landrace and restorer-to-fertility () genes. European sources show an oligogenic inheritance, with major and minor genes, and mostly result in low-to-moderate pollen-fertility levels. This results in higher susceptibility to ergot () because rye pollen and ergot spores are in strong competition for the unfertilized stigma. genes from non-adapted Iranian primitive rye and old Argentinean cultivars proved to be most effective. The major gene in these sources was localized on chromosome 4RL, which is also a hotspot of restoration in other . Marker-based introgression into elite rye materials led to a yield penalty and taller progenies. The gene of IRAN IX was fine-mapped, and two linked genes of equal effects were detected. Commercial hybrids with this gene showed a similar low ergot infection when compared with population cultivars. The task of the future is to co-adapt these exotic genes to European elite gene pools by genomic-assisted breeding.