Silencing of SlCAND1 expression resulted in dwarfish, loss of apical dominance, early flowering, suppression of seed germination, and abnormal root architecture in tomato Cullin-RING E3 ligases (CRLs)-dependent ubiquitin proteasome system mediates degradation of numerous proteins that controls a wide range of developmental and physiological processes in eukaryotes. Cullin-associated Nedd8-dissociated protein 1 (CAND1) acts as an exchange factor allowing substrate recognition part exchange and plays a vital role in reactivating CRLs. The present study reports on the identification of SlCAND1, the only one CAND gene in tomato. SlCAND1 expression is ubiquitous and positively regulated by multiple plant hormones. Silencing of SlCAND1 expression using RNAi strategy resulted in a pleiotropic and gibberellin/auxin-associated phenotypes, including dwarf plant with reduced internode length, loss of apical dominance, early flowering, low seed germination percentage, delayed seed germination speed, short primary root, and increased lateral root proliferation and elongation. Moreover, application of exogenous GA3 or IAA could partly rescue some SlCAND1-silenced phenotypes, and the expression levels of gibberellin/auxin-related genes were altered in SlCAND1-RNAi lines. These facts revealed that SlCAND1 is required for gibberellin/auxin-associated regulatory network in tomato. Although SlCAND1 is crucial for multiple developmental processes during vegetative growth stage, SlCAND1-RNAi lines didn't exhibit visible effect on fruit development and ripening. Meanwhile, we discussed that multiple physiological functions of SlCAND1 in tomato are different to previous report of its ortholog in Arabidopsis. Our study adds a new perspective on the functional roles of CAND1 in plants, and strongly supports the hypothesis that CAND1 and its regulated ubiquitin proteasome system are pivotal for plant vegetative growth but possibly have different roles in diverse plant species.

中文翻译：

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SlCAND1 编码与 cullin 相关的 Nedd8 解离蛋白 1，可调节番茄的株高、开花时间、种子萌发和根结构。

SlCAND1 表达的沉默导致番茄矮小、顶端优势丧失、早期开花、种子萌发抑制和异常根结构在番茄中 Cullin-RING E3 连接酶 (CRL) 依赖的泛素蛋白酶体系统介导多种蛋白质的降解，这些蛋白质控制范围广泛真核生物的发育和生理过程。Cullin 相关的 Nedd8 解离蛋白 1 (CAND1) 充当交换因子，允许底物识别部分交换，并在重新激活 CRL 中起着至关重要的作用。本研究报告了番茄中唯一一个CAND基因SlCAND1的鉴定。SlCAND1 的表达无处不在，并且受到多种植物激素的正向调控。使用 RNAi 策略沉默 SlCAND1 表达导致多效性和赤霉素/生长素相关表型，包括节间长度缩短、顶端优势丧失、开花早、种子发芽率低、种子发芽速度延迟、初生根短、侧根增殖和伸长增加的矮化植物。此外，外源 GA3 或 IAA 的应用可以部分挽救一些 SlCAND1 沉默的表型，并且在 SlCAND1-RNAi 系中赤霉素/生长素相关基因的表达水平发生了改变。这些事实表明，SlCAND1 是番茄中赤霉素/生长素相关调控网络所必需的。尽管 SlCAND1 在营养生长阶段对多个发育过程至关重要，但 SlCAND1-RNAi 系对果实发育和成熟没有表现出明显的影响。同时，我们讨论了SlCAND1在番茄中的多种生理功能与其在拟南芥中的直系同源物的先前报道不同。我们的研究为 CAND1 在植物中的功能作用提供了新的视角，并强烈支持 CAND1 及其调节的泛素蛋白酶体系统对植物营养生长至关重要但在不同植物物种中可能具有不同作用的假设。