Suo Jinwei, Liu Ya, Yan Jiawen, Li Qianxi, Chen Weijie, Liu Zhihui, Zhang Zuying, Hu Yuanyuan, Yu Weiwu, Yan Jingwei, Song Lili, Wu Jiasheng
State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, Zhejiang, 311300, China.
New Phytol. 2024 Sep;243(5):1823-1839. doi: 10.1111/nph.19972. Epub 2024 Jul 15.
Cone enlargement is a crucial process for seed production and reproduction in gymnosperms. Most of our knowledge of cone development is derived from observing anatomical structure during gametophyte development. Therefore, the exact molecular mechanism underlying cone enlargement after fertilization is poorly understood. Here, we demonstrate that sucrose promotes cone enlargement in Torreya grandis, a gymnosperm species with relatively low rates of cone enlargement, via the TgNGA1-TgWRKY47-TgEXPA2 pathway. Cell expansion plays a significant role in cone enlargement in T. grandis. C labeling and sucrose feeding experiments indicated that sucrose-induced changes in cell size and number contribute to cone enlargement in this species. RNA-sequencing analysis, transient overexpression in T. grandis cones, and stable overexpression in tomato (Solanum lycopersicum) suggested that the expansin gene TgEXPA2 positively regulates cell expansion in T. grandis cones. The WRKY transcription factor TgWRKY47 directly enhances TgEXPA2 expression by binding to its promoter. Additionally, the NGATHA transcription factor TgNGA1 directly interacts with TgWRKY47. This interaction suppresses the DNA-binding ability of TgWRKY47, thereby reducing its transcriptional activation on TgEXPA2 without affecting the transactivation ability of TgWRKY47. Our findings establish a link between sucrose and cone enlargement in T. grandis and elucidate the potential underlying molecular mechanism.
球果增大是裸子植物种子生产和繁殖的关键过程。我们对球果发育的大部分了解都来自于观察配子体发育过程中的解剖结构。因此，受精后球果增大的确切分子机制尚不清楚。在这里，我们证明蔗糖通过TgNGA1-TgWRKY47-TgEXPA2途径促进了榧树（一种球果增大率相对较低的裸子植物）的球果增大。细胞扩张在榧树球果增大中起重要作用。碳同位素标记和蔗糖饲喂实验表明，蔗糖诱导的细胞大小和数量变化有助于该物种的球果增大。RNA测序分析、在榧树球果中的瞬时过表达以及在番茄（Solanum lycopersicum）中的稳定过表达表明，扩张蛋白基因TgEXPA2正向调节榧树球果中的细胞扩张。WRKY转录因子TgWRKY47通过结合其启动子直接增强TgEXPA2的表达。此外，NGATHA转录因子TgNGA1直接与TgWRKY47相互作用。这种相互作用抑制了TgWRKY47的DNA结合能力，从而降低了其对TgEXPA2的转录激活作用，而不影响TgWRKY47的反式激活能力。我们的研究结果建立了蔗糖与榧树球果增大之间的联系，并阐明了潜在的分子机制。
