Yue Yuanzheng, Zhu Wuwei, Shen Huimin, Wang Hongtao, Du Juhua, Wang Lianggui, Hu Huirong
College of Landscape Architecture, Nanjing Forestry University, Nanjing 210037, China.
Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China.
Int J Mol Sci. 2023 Jul 26;24(15):11999. doi: 10.3390/ijms241511999.
Petal size is a key indicator of the ornamental value of plants, such as L., which is a popular ornamental species worldwide. Our previous study identified a flower-specific expression pattern of a DNA-binding one finger (Dof)-type transcription factor (TF) , in the semi-flowering and full-flowering stages of petunia. In this study, subcellular localization and activation assays showed that was localized in the cell nucleus and could undergo in vitro self-activation. The expression levels of tended to be significantly up-regulated at the top parts of petals during petunia flower opening. Transgenic petunia 'W115' and tobacco plants overexpressing showed similar larger petal phenotypes. The cell sizes at the middle and top parts of transgenic petunia petals were significantly increased, along with higher levels of endogenous indole-3-acetic acid (IAA) hormone. Interestingly, the expression levels of two TFs, and , which were reported as negative regulators for flower development, were dramatically increased, while the accumulation of jasmonic acid (JA), which induces expression, was also significantly enhanced in the transgenic petals. These results indicated that overexpression could increase petal size by enhancing the synthesis of endogenous IAA in petunias. Moreover, a JA-related feedback regulation mechanism was potentially activated to prevent overgrowth of petals in transgenic plants. This study will not only enhance our knowledge of the Dof TF family, but also provide crucial genetic resources for future improvements of plant ornamental traits.
花瓣大小是植物观赏价值的关键指标，例如矮牵牛（Petunia × hybrida），它是一种在全球范围内广受欢迎的观赏植物。我们之前的研究确定了一种DNA结合单指（Dof）型转录因子（TF）在矮牵牛半开花期和完全开花期的花特异性表达模式。在本研究中，亚细胞定位和激活分析表明，该转录因子定位于细胞核中，并且能够在体外进行自我激活。在矮牵牛花朵开放过程中，该转录因子在花瓣顶部的表达水平往往会显著上调。过表达该转录因子的转基因矮牵牛‘W115’和烟草植株表现出类似的较大花瓣表型。转基因矮牵牛花瓣中部和顶部的细胞大小显著增加，同时内源吲哚-3-乙酸（IAA）激素水平也更高。有趣的是，据报道作为花发育负调控因子的两个转录因子的表达水平显著增加，而诱导该转录因子表达的茉莉酸（JA）在转基因花瓣中的积累也显著增强。这些结果表明，过表达该转录因子可以通过增强矮牵牛内源IAA的合成来增加花瓣大小。此外，可能激活了一种与JA相关的反馈调节机制，以防止转基因植物花瓣过度生长。这项研究不仅将增进我们对Dof转录因子家族的了解，还将为未来改善植物观赏性状提供关键的遗传资源。
