The Circadian Clock Gene, TaPRR1, Is Associated With Yield-Related Traits in Wheat (Triticum aestivum L.)

Abstract

Timing of flowering is crucial for the transformation from vegetative to reproductive growth in the important food crop, wheat (<i>Triticum aestivum</i> 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 <i>TaPRR1</i>, demonstrating that natural variations in <i>TaPRR1</i> are associated with significant differences in yield-related traits including heading date, plant height and thousand grain weight. <i>TaPRR1-6A-Hapla</i> showed an earlier heading date, advanced by 0.9 to 1.7%. <i>TaPRR1-6B-Hapla</i> and <i>TaPRR1-6D-Hapla</i> 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 <i>TaPRR1</i> 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 <i>TaPRR1-6A-Hapla</i>, <i>TaPRR1-6B-Haplb</i>, and <i>TaPRR1-6D-Haplb</i> in different agro-ecological production zones. Furthermore, analysis of molecular variance of the distribution frequency of <i>TaPRR1</i> haplotypes suggested significant differences in haplotype distribution frequency between landraces and modern cultivars. Our study provides a basis for in-depth understanding of <i>TaPRR1</i> function on yield-related traits in wheat, as well as establishing theoretical guidance for wheat molecular marker-assisted breeding.