Data_Sheet_1_SlTPL1 Silencing Induces Facultative Parthenocarpy in Tomato.zip

Facultative parthenocarpy is of great practical value. However, the molecular mechanism underlying facultative parthenocarpy remains elusive. Transcriptional co-repressors (TPL) act as a central regulatory hub controlling all nine phytohormone pathways. Previously, we proved that SlTPLs participate in the auxin signaling pathway by interacting with auxin/indole acetic acid (Aux/IAAs) in tomato; however, their function in fruit development has not been studied. In addition to their high expression levels during flower development, the interaction between SlTPL1 and SlIAA9 stimulated the investigation of its functional significance via RNA interference (RNAi) technology, whereby the translation of a protein is prevented by selective degradation of its encoded mRNA. Down-regulation of SlTPL1 resulted in facultative parthenocarpy. Plants of SlTPL1-RNAi transgenic lines produced similar fruits which did not show any pleiotropic effects under normal conditions. However, they produced seedless fruits upon emasculation and under heat stress conditions. Furthermore, SlTPL1-RNAi flower buds contained higher levels of cytokinins and lower levels of abscisic acid. To reveal how SlTPL1 regulates facultative parthenocarpy, RNA-seq was performed to identify genes regulated by SlTPL1 in ovaries before and after fruit set. The results showed that down-regulation of SlTPL1 resulted in reduced expression levels of cytokinin metabolism-related genes, and all transcription factors such as MYB, CDF, and ERFs. Conversely, down-regulation of SlTPL1 induced the expression of genes related to cell wall and cytoskeleton organization. These data provide novel insights into the molecular mechanism of facultative tomato parthenocarpy and identify SlTPL1 as a key factor regulating these processes.

兼性单性结实（facultative parthenocarpy）具有重要的实用价值，但其分子机制仍未明确。转录共抑制因子（Transcriptional co-repressors, TPL）作为核心调控枢纽，可调控所有九类植物激素信号通路。此前本团队已证实，番茄中SlTPL家族蛋白可通过与生长素/吲哚乙酸蛋白（auxin/indole acetic acid, Aux/IAA）互作参与生长素信号通路，但它们在果实发育中的功能尚未被研究。除在花发育阶段高表达外，SlTPL1与SlIAA9的互作结果促使我们通过RNA干扰（RNA interference, RNAi）技术探究其功能意义——该技术可通过选择性降解靶基因的mRNA阻断蛋白质翻译。下调SlTPL1的表达可诱导产生兼性单性结实。SlTPL1-RNAi转基因株系在正常生长条件下所结果实与野生型无显著差异，未表现出任何多效性表型；但在去雄处理及热胁迫条件下，该株系可产生无籽果实。进一步检测发现，SlTPL1-RNAi的花蕾中细胞分裂素（cytokinins）水平显著升高，而脱落酸（abscisic acid）水平则显著降低。为揭示SlTPL1调控兼性单性结实的分子机制，本研究通过RNA测序（RNA-seq）分析了坐果前后子房（ovaries）中受SlTPL1调控的基因。结果显示，SlTPL1表达下调会抑制细胞分裂素代谢相关基因以及MYB、CDF、ERF等转录因子的表达；反之，SlTPL1表达下调则会诱导细胞壁与细胞骨架组织相关基因的表达。本研究数据为解析番茄兼性单性结实的分子机制提供了新视角，并确定SlTPL1是调控该过程的关键因子。