biological rhythm clock is the core part of photoperiod regulation, and pseudo-response regulators (PRRs) are key components of biological rhythm regulation networks. As a member of the PRR family, the famous green revolution gene of wheat Ppd-1 (TaPRR37) has made significant contributions to increasing wheat yield. The Ppd-1 gene not only affects the photoperiod sensitivity of wheat, but is also related to important agronomic traits such as plant height and thousand grain weight of wheat. In addition, wheat PRR family member TaPRR73 has been reported to affect the heading stage and plant height of wheat. However, for the core member of the wheat biological clock, its function is relatively little researched.
Recently, the wheat molecular breeding innovation team of Shandong University cooperated with the Institute of Crop Science of the Chinese Academy of Agricultural Sciences and the Institute of Plant Science of the Chinese Academy of Sciences to publish a paper titled "The Circadian Clock Gene, TaPRR1, Is Associated With Yield-Related Traits in Wheat (Triticum aestivumL.)" online in the Frontiers in Plant Science. This study conducted functional analysis on the core member of the wheat biological clock TaPRR1, and mainly obtained the following research results:
(1) The different haplotypes of the wheat biological clock gene TaPRR1 were significantly correlated with yield traits. Molecular markers are developed based on the TaPRR1 polymorphic site. Combining the phenotypic data of 19 environmental natural populations, the relationship between different haplotypes of TaPRR1 and wheat yield traits was clarified through correlation analysis. At the same time, based on the 660K chip data, combined with the molecular marker in the 2Mb interval upstream and downstream of TaPRR1, the function of TaPRR1 was further verified (Figure 1). It is worth noting that TaPRR1-A1 is significantly related to the wheat heading period, and TaPRR1-6A-Haplan was 0.9-1.7% earlier than TaPRR1-6A-Hapla. TaPRR1-B1 and TaPRR1-D1 affect the plant height and 1,000 grain weight of wheat. The amplitudes of TaPRR1-6B-Haplan and TaPRR1-6D-Haplan reduced plant height and increased 1,000 grain weight were 13.3-26.4% and 6.3-17.3%, respectively.
(2) Analysis of expression characteristics and transcriptional activity of wheat TaPRR1 gene. The 48-hour expression profile of TaPRR1 is characterized by circadian rhythm, with two expression peaks under short and long sun conditions: 9 and 18 hours after dawn, respectively. There are also differences in the time and expression amount of expression peaks of different TaPRR1 haplotypes (Figure 2). Subcellular localization and transcriptional activity analysis showed that TaPRR1 is a nuclear localization protein whose transcriptional activity is controlled by the IR domain.
(3) There is genetic variation and differentiation between wheat TaPRR1 gene and modern breeding varieties. Haplotype network analysis shows that the genetic variants of TaPRR1 differ between local species and modern species. Through molecular variance analysis, we speculate that TaPRR1-A1 haplotype has moderate genetic differentiation, while TaPRR1-B1 and TaPRR1-D1 have high genetic differentiation. Although the geographical distribution shows that TaPRR1-6A-Hapla, TaPRR1-6B-Haplb and TaPRR1-6D-Haplb are the main distribution haplotypes. However, in the process of modern breeding, the proportion of excellent haplotypes TaPRR1-6B-Haplan and TaPRR1-6D-Haplan has increased significantly, and has been artificially selected (Figure 3).
Mermeal Molecular Breeding Innovation Team of Shandong University Sun Han Associate Professor, Institute of Botany, Chinese Academy of Sciences Dr. Guo Zhiai , and Researcher Jia Jizeng , Institute of Workshop, Chinese Academy of Agricultural Sciences, are the co-corresponding authors of the paper. The research was funded by projects such as the National Natural Science Foundation of China, Shandong Provincial Natural Science Foundation of China, Yantai City Key R&D Plan.
