Flower formation is a basic condition for fruit set in all flowering plants. The normal stamen of tomato flower fused together to form a yellow cylinder surrounding the carpels. In this study, we identified an un-fused flower (uf) tomato mutant that is defective in petal, carpal and stamen fusion and lateral outgrowth. After RNA-seq-based BSA (BSR), the candidate region location was identified in the long arm of chromosome 3. Using map-based cloning with InDel and CAPS markers, the UF candidate gene was mapped in a 104 kb region. In this region, a WOX (WUSCHEL-related homeobox) transcription factor SlWOX1 was considered as a candidate of UF as there is a 72bp deletion in its second exon in uf mutant. The mutations of SlWOX1 generated by CRISPR/CAS9 approach under wild-type background reproduced the phenotypes of uf mutant, indicating that the SlWOX1 gene is indeed UF. Interestingly, expression analysis of organ lateral polarity determinant genes showed that abaxial genes (SlYABBY5 and SlARF4) and adaxial genes (AS and HD-ZIPIII) were significantly down-regulated in the uf mutant, which is different to that in Arabidopsis and petunia. In conclusion, this work revealed a novel function of SlWOX1 in the regulation of flower development in tomato.

中文翻译：

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UF，一种 WOX 基因，调节番茄未融合花的一种新表型

花的形成是所有开花植物坐果的基本条件。番茄花的正常雄蕊融合在一起形成围绕心皮的黄色圆柱体。在这项研究中，我们确定了一个未融合的花 (uf) 番茄突变体，该突变体在花瓣、腕骨和雄蕊融合以及侧向生长方面存在缺陷。在基于 RNA-seq 的 BSA (BSR) 之后，在 3 号染色体的长臂中确定了候选区域位置。使用带有 InDel 和 CAPS 标记的基于图谱的克隆，将 UF 候选基因定位在 104 kb 区域。在该区域，WOX（WUSCHEL 相关同源框）转录因子 SlWOX1 被认为是 UF 的候选者，因为 uf 突变体的第二个外显子有 72bp 缺失。在野生型背景下通过 CRISPR/CAS9 方法产生的 SlWOX1 突变再现了 uf 突变体的表型，表明 SlWOX1 基因确实是 UF。有趣的是，器官侧向极性决定基因的表达分析表明，在 uf 突变体中，与拟南芥和矮牵牛不同，离轴基因（SlYABBY5 和 SlARF4）和近轴基因（AS 和 HD-ZIPIII）显着下调。总之，这项工作揭示了 SlWOX1 在调控番茄花发育中的新功能。