Super-Open Flowering Mutant (sof1) of Barley

A wild barley (Hordeum vulgare ssp. spontaneum) strain OUH602 originated from the Caspian See region were grown in the field of the Institute of Radiation Breeding, National Institute of Agrobiological Sciences, Japan and the plants (defined as M₁) were exposed to γ irradiation at 0.24 – 0.77 Gy/day and 5 days irradiation/week from the seedling to the maturation stage by means of a cobalt 60 (⁶⁰Co) source. About 1,600 M₃ lines derived from M₂ plants (10 M₃ plants in each line) were forward-screened for morphological mutation. A single plant in the line #44205 showed a “super-open flowering” phenotype. The palea and lemma of this mutant gaped wider than that of the wild type. The lodicule, a structure found in the floret of many grass species and functionally related to the petal in the hermaphroditic angiosperm flower, of this mutant was significantly larger in length and depth than that of wild type. A single recessive gene controlled the phenotype so the symbol was named sof1.