Gong Feifei, Wang Xiaoyu, Zhao Qingcui, Wang Dan, Yan Huijun, Wang Qigang, Zhang Yiping, Zhang Yixin, Jian Hongying, Qiu Xianqin, Tang Kaixue, Zhang Hao, Jing Weikun
Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture, College of Horticulture, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, China.
Flower Research Institute of Yunnan Academy of Agricultural Sciences, No. 2238 Beijing Road, Panlong District, Kunming, Yunnan 650205, China.
Hortic Res. 2025 May 21;12(8):uhaf134. doi: 10.1093/hr/uhaf134. eCollection 2025 Aug.
Cell expansion in petals plays a crucial role in flower opening and final size in rose (), which largely determines its market value. While cell expansion is known to be closely associated with gibberellins (GAs), the underlying molecular mechanism remains elusive. Here, we measured the levels of GAs during flower opening and demonstrated that GA treatment significantly increases petal size. Moreover, we identified RhMYB70, an R2R3 MYB transcription factor, whose expression was inhibited by GA treatment. silencing resulted in larger petals and petal cell size than those of TRV control. Through transcriptome analysis and biochemical identification, RhMYB70 could directly bind to the promoter of the cellulose synthase gene and repress its transcription, thereby resulting in decreased cellulose content of petals and final size. In addition, we also identified the GA biosynthesis gene as an RhMYB70 target and demonstrated that RhMYB70 directly binds to and inhibits the promoter activity of , leading to decreased cellulose content of petals and petal size. Besides, knocking down expression not only resulted in increasing GA and GA levels in petals compared to TRV but also elevated cellulose content. Together, our findings reveal that the feedback regulation of GAs and RhMYB70 signaling fine-tunes cell expansion and petal size by modulating cellulose content of rose petals, providing genetic targets for improving rose flower quality.
花瓣中的细胞扩张在玫瑰花朵开放和最终大小方面起着关键作用，这在很大程度上决定了其市场价值。虽然已知细胞扩张与赤霉素（GAs）密切相关，但其潜在的分子机制仍不清楚。在这里，我们测量了花朵开放过程中赤霉素的水平，并证明赤霉素处理显著增加了花瓣大小。此外，我们鉴定出一个R2R3 MYB转录因子RhMYB70，其表达受到赤霉素处理的抑制。与TRV对照相比，RhMYB70沉默导致花瓣和花瓣细胞尺寸更大。通过转录组分析和生化鉴定，RhMYB70可以直接结合到纤维素合酶基因的启动子上并抑制其转录，从而导致花瓣纤维素含量降低和最终尺寸减小。此外，我们还鉴定出赤霉素生物合成基因作为RhMYB70的靶标，并证明RhMYB70直接结合并抑制其启动子活性，导致花瓣纤维素含量和花瓣尺寸降低。此外，与TRV相比，敲低表达不仅导致花瓣中赤霉素和赤霉素水平增加，还提高了纤维素含量。总之，我们的研究结果表明，赤霉素和RhMYB70信号的反馈调节通过调节玫瑰花瓣的纤维素含量来微调细胞扩张和花瓣大小，为改善玫瑰花朵品质提供了遗传靶点。
