GRAS family transcription factors (TF) are involved in multiple biological processes in plants. In recent years among the 54 identified GRAS proteins, only few have been studied functionally in tomato (Solanum lycopersicum). In the present study, a novel and previously uncharacterized member of tomato GRAS transcription factors family SlGRAS15 was isolated and functionally characterized. It was observed that SlGRAS15 preferably expressed in roots, followed by young leaves, stem, and comparatively low transcripts levels were noticed in all other tissues. To explore the SlGRAS15 function in detail, an RNA interference (RNAi) vector targeting SlGRAS15 was constructed and transformed into tomato plants. The transgenic plants carrying SlGRAS15-RNAi displayed pleiotropic phenotypes associated with multiple agronomical traits including reduced plant height and small leaf size with pointed margins, increased node number, lateral shoots, and petiolules length. In addition, transcriptional analysis revealed that silencing SlGRAS15 altered vegetative growth by downregulating gibberellin (GA) biosynthesis genes and stimulating the GA deactivating genes, thus lowering the endogenous GA content in tomato transgenic lines. Moreover, the GA signaling downstream gene (SlGAST1) was downregulated but the negative regulator of GA signaling (SlDELLA) was upregulated by SlGRAS15 silencing. The root and hypocotyl length in SlGRAS15-RNAi lines showed reduced growth under normal conditions (Mock) as compared with the wild type (WT) control plants. Taken together, these findings enhanced our understanding that suppression of SlGRAS15 lead to a series of developmental processes by modulating gibberellin signaling and demonstrate an association between the SlGRAS15 and GA signaling pathway during vegetative growth in tomato.

中文翻译：

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SlGRAS15的下调操纵了番茄的植物结构（茄属植物）

GRAS家族转录因子（TF）参与植物的多个生物过程。近年来，在54种已鉴定的GRAS蛋白中，在番茄（Solanum lycopersicum）中进行功能研究的很少。在本研究中，番茄GRAS转录因子家族SlGRAS15的一个新的和以前未表征的成员是分离和功能表征。观察到SlGRAS15优选在根中表达，然后在所有其他组织中发现幼叶，茎和相对较低的转录水平。为了详细研究SlGRAS15的功能，靶向SlGRAS15的RNA干扰（RNAi）载体被建造并转化为番茄植物。携带SlGRAS15 -RNAi的转基因植物表现出与多种农艺性状相关的多效性表型，包括植物高度降低和叶尖尖的小叶尺寸，节数，侧枝和叶柄长度的增加。另外，转录分析显示沉默SlGRAS15通过下调赤霉素（GA）生物合成基因并刺激GA失活基因来改变营养生长，从而降低番茄转基因品系中的内源GA含量。此外，GA信号下游基因（SlGAST1）被下调，而GA信号负调控子（SlDELLA）被SlGRAS15上调。沉默。与野生型（WT）对照植物相比，SlGRAS15 -RNAi系中的根和下胚轴长度在正常条件下（模拟）显示出减少的生长。综上所述，这些发现增强了我们的理解，即通过调节赤霉素信号传导而抑制SlGRAS15会导致一系列发育过程，并证明了在番茄营养生长过程中SlGRAS15和GA信号传导途径之间的关联。