Mutations in TaPRR59 impact transcript levels of some key flowering genes and show earlier heading time and reduced plant height. Favorable haplotype TaPRR59-A1-Hapla was positively selected in wheat breeding programs. The circadian clock system is a crucial endogenous rhythmic regulatory mechanism with a significant role in plant growth and development. The pseudo-response regulator (PRR) family is a pivotal component of circadian networks. In the present study, we cloned the wheat PRR family member TaPRR59 and investigated its function using gene editing, transcriptome sequencing, haplotype analysis, and association analysis. The expression profile of TaPRR59 over a 24-h period exhibited a diurnal rhythmic expression pattern. Luciferase transient transcriptional assay demonstrated that TaPRR59 acts as a transcriptional repressor in the nucleus. The taprr59-ABD-KO gene-edited lines produced using the CRISPR/Cas9 genome-editing system had earlier heading time and reduced plant height. Overexpression of TaPRR59-D1 in rice significantly delayed the heading date, reduced plant height and thousand-grain weight, and increased the number of grains per panicle. Transcriptome analysis revealed the transcript levels of several key flowering genes and chlorophyll a-b binding protein-related genes were up- or down-regulated in the taprr59 mutant plants. Association analysis showed that natural variations at TaPRR59-A1, TaPRR59-B1, and TaPRR59-D1 were significantly associated with yield traits such as plant height, thousand-grain weight, and heading date. Geographical analysis showed distinctive distribution characteristics of TaPRR59 haplotypes in different agroecological production zones. Additionally, the significant difference in frequency of the favorable haplotype TaPRR59-A1-Hapla between landraces and modern cultivars indicates that it has been subject to directional selection during wheat breeding. This research provided novel insights into the influence of the circadian clock system on agronomic traits and provided useful molecular markers and genetic resources for wheat breeding.
