Photoperiod-sensitive cytoplasmic male sterile elite lines for hybrid wheat breeding, showing high cross-pollination fertility under long-day conditions

Photoperiod-sensitive cytoplasmic male sterility (PCMS) caused by Aegilops crassa cytoplasm under long-day (LD) photoperiods (≧15 h) has been proposed as a two-line system for producing hybrid varieties in common wheat (Triticum aestivum). The PCMS line is maintained by self-pollination under short-day (SD) conditions, and hybrid seeds can be produced through outcrossing of the PCMS line with a pollinator line under LD conditions. Maintainer lines of the PCMS lines are not necessary in this system. In our previous study, we developed two PCMS lines with the genetic background of the Japanese wheat cultivar ‘Fukuotome’, which showed high male sterility under LD conditions and high seed fertility under SD conditions. These PCMS lines were from a BC2 generation and were not genetically pure. Therefore, we screened the progeny of the BC2 lines, and identified BC2F8 lines that showed high male sterility and high cross-pollination fertility under LD conditions and high seed fertility under SD conditions. Furthermore, we screened the pollinator lines suitable for the PCMS system. These PCMS elite lines and selected pollinator lines will be useful for developing hybrid wheat varieties.