Genetic analysis on the fertility restoration by Triticum aestivum cv. Chinese Spring against photoperiod-sensitive cytoplasmic male sterility

Triticum aestivum cv. Norin 26 with Aegilops crassa cytoplasm shows photo-period-sensitive cytoplasmic male sterility (PCMS). This alloplasmic line is almost completely male sterile under a long-day condition (15 h light period), but highly male fertile under a short-day condition (14.5 h light period). The alloplasmic line of T. aestivum cv. Chinese Spring with the same cytoplasm does not express PCMS. Conventional and telosomic analyses revealed that the fertility restoration manifested by Chinese Spring is controlled mainly by a single dominant gene (designated Rfd1) located on the long arm of chromosome 7B, and that a large number of modifiers are involved in modifying the level of fertility restoration. The function of the Rfd1 gene is expressed sporophytically. A slight certation was observed between the two types of pollen grains, one carrying and the other not carrying this gene, under the presence of Ae. crassa cytoplasm.