show Abstracthide AbstractWe backcrossed two early heading lines of synthetic hexaploid wheat with four Japanese elite cultivars to develop the early heading lines of bread wheat. In total, nine early heading lines, which showed two to eight days earlier heading time than their parental cultivars in the field conditions, were selected and established from the selfed progenies of the two- or three-times backcrossed populations. RNA sequencing-based genotyping was performed to detect single nucleotide polymorphisms between the selected lines and their parental wheat cultivars, which revealed the chromosomal regions transmitted from the parental synthetic wheat to the selected lines.