Rice Genomics and Genetics 2024, Vol.15, No.1, 28-35 http://cropscipublisher.com/index.php/rgg 28 Scientific Review Open Access Genetic Regulation of Diurnal Flowering Time Divergence in Rice: The Role of the OsMYB8 and OsJAR1 Module Jianli Zhong , Jim Fang Hainan Institute of Tropical Agricultural Resources, Sanya, 572025, Hainan, China Corresponding author email: zhongjianli8888@gmail.com Rice Genomics and Genetics, 2024, Vol.15, No.1 doi: 10.5376/rgg.2024.15.0004 Received: 01 Dec., 2023 Accepted: 03 Jan., 2024 Published: 15 Jan., 2024 Copyright © 2024 Zhong and Fang, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Zhong J.L., and Fang J., 2024, Genetic regulation of diurnal flowering time divergence in rice: the role of the OsMYB8 and OsJAR1 module, Rice Genomics and Genetics, 15(1): 28-35 (doi: 10.5376/rgg.2024.15.0004) On March 13, 2024, a joint research achievement by the State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, School of Life Sciences, South China Agricultural University, the Guangdong Provincial Key Laboratory of New Technology in Rice Breeding, Rice Research Institute of Guangdong Academy of Agricultural Sciences, and the Life Sciences Technology Center of China National Seed Group Co., Ltd. was published in Nature Communications. The paper, titled "Natural variation in OsMYB8 confers diurnal floret opening time divergence between indica and japonica subspecies," had Yajun Gou and Yueqing Heng as co-first authors, with Rongxin Shen and Haiyang Wang as co-corresponding authors. The study was funded by the National Natural Science Foundation of China Innovation Group Project and the Hainan Yazhou Bay Seed Laboratory Commander Project, among others. It identified the OsMYB8 gene as a key factor regulating the divergence in diurnal flowering time in rice. The interaction between OsMYB8 and OsJAR1 significantly affects the flowering time of indica and japonica rice. Transferring the indica allele of OsMYB8 into japonica rice effectively advances flowering time, providing a new strategy for indica-japonica hybrid breeding. 1 Experimental Data Analysis This research meticulously recorded the behavior of indica and japonica rice varieties flowering at different times of the day. RNA sequencing (RNA-seq) analysis revealed that OsMYB8 expression levels increased before flowering, and this upregulation directly promoted the expression of the OsJAR1 gene. The interaction between OsMYB8 and OsJAR1 further influenced the expression of genes regulating cell permeability and cell wall remodeling, collectively facilitating floret opening. Figure 1 showed the divergence in Diurnal Flowering Opening Time (DFOT) between the two rice subspecies. Figure 1a compared the DFOT of indica (n=28) and japonica (n=12) rice varieties in Guangzhou in October 2019, showing that indica varieties generally flowered earlier than japonica. Figures 1b and 1c compared the floret opening of the indica rice TFB and the japonica ZH11 at 10:30 AM and 12:00 PM, showing significant differences, with TFB opening earlier. Figures 1d and 1e recorded the DFOT changes of TFB and ZH11 in June and October 2020, showing the stability of their DFOT across different seasons. Figure 1f displayed the changes in pistil morphology of TFB and ZH11 at different times of the day using stereomicroscope photos, while figure 1g explained how the pistil was considered an ellipsoid for volume measurement. Figure 1h quantitatively compared the pistil volumes of ZH11 and TFB at different times, using the ellipsoid volume formula for calculations. Finally, figure 1i analyzed the water content of 100 pistils of ZH11 and TFB at different times, providing experimental data for subsequent exploration of the association between DFOT and water content. Therefore, these results highlighted the significant divergence in DFOT between the two rice subspecies, which is of great significance for rice breeding and understanding the impact of different biological clocks on plant flowering.
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