| Summary: | Timing of flowering is crucial for the transformation from vegetative to reproductive growth in the important food crop, wheat (Triticum aestivum L.). The circadian clock is a central part of photoperiod regulation, with Pseudo-Response Regulators (PRRs) representing key components of circadian networks. However, little is known about the effects of PRR family members on yield-related traits in crop plants. In this study, we identified polymorphisms and haplotypes of TaPRR1, demonstrating that natural variations in TaPRR1 are associated with significant differences in yield-related traits including heading date, plant height and thousand grain weight. TaPRR1-6A-Hapla showed an earlier heading date, advanced by 0.9 to 1.7%. TaPRR1-6B-Hapla and TaPRR1-6D-Hapla displayed reduced plant height and increased thousand grain weight of up to 13.3 to 26.4% and 6.3 to 17.3%, respectively. Subcellular localization and transcriptional activity analysis showed that TaPRR1 is a nuclear localization protein with transcriptional activity controlled by an IR domain. The expression profiles of TaPRR1 genes over a 48-h period were characterized by circadian rhythms, which had two peaks under both short- and long- day conditions. In addition, geographical distribution analysis indicated higher distribution frequencies of TaPRR1-6A-Hapla, TaPRR1-6B-Haplb, and TaPRR1-6D-Haplb in different agro-ecological production zones. Furthermore, analysis of molecular variance of the distribution frequency of TaPRR1 haplotypes suggested significant differences in haplotype distribution frequency between landraces and modern cultivars. Our study provides a basis for in-depth understanding of TaPRR1 function on yield-related traits in wheat, as well as establishing theoretical guidance for wheat molecular marker-assisted breeding.
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