Abscission, a cell separation process, is an important trait that influences grain and fruit yield. We previously reported that BEL1-LIKE HOMEODOMAIN 4 (SlBL4) is involved in chloroplast development and cell wall metabolism in tomato fruit. In the present study, we showed that silencing SlBL4 resulted in the enlargement and pre-abscission of the tomato (Solanum lycopersicum cv. Micro-TOM) fruit pedicel. The anatomic analysis showed the presence of more epidermal cell layers and no obvious abscission zone (AZ) in the SlBL4 RNAi lines compared with the wild-type plants. RNA-seq analysis indicated that the regulation of abscission by SlBL4 was associated with the altered abundance of genes related to key meristems, auxin transporters, signaling components, and cell wall metabolism. Furthermore, SlBL4 positively affected the auxin concentration in the abscission zone. A dual-luciferase reporter assay revealed that SlBL4 activated the transcription of the JOINTLESS, OVATE, PIN1, and LAX3 genes. We reported a novel function of SlBL4, which plays key roles in fruit pedicel organogenesis and abscission in tomatoes.

中文翻译：

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番茄 SlBL4 在果梗器官发生和脱落中起重要作用

脱落是一种细胞分离过程，是影响谷物和果实产量的重要性状。我们之前报道过BEL1-LIKE HOMEODOMAIN 4(SLBL4) 参与番茄果实中的叶绿体发育和细胞壁代谢。在本研究中，我们证明了沉默SLBL4导致番茄变大并提前脱落（番茄品种 微型汤姆) 果梗。解剖分析显示，表皮细胞层较多，无明显脱落区（AZ）。SLBL4RNAi 系与野生型植物相比。RNA-seq 分析表明，脱落的调节是由SLBL4与关键分生组织、生长素转运蛋白、信号成分和细胞壁代谢相关的基因丰度改变有关。此外，SLBL4对脱落区的生长素浓度产生积极影响。双荧光素酶报告基因分析表明，SlBL4 激活了无接头,卵形,PIN1,和LAX3基因。我们报道了 SlBL4 的一种新功能，它在番茄的果梗器官发生和脱落中起关键作用。