Premature abscission of flowers and fruits triggered by low light stress can severely reduce crop yields. However, the underlying molecular mechanism of this organ abscission is not fully understood. Here, we show that a gene (SlCLV3) encoding CLAVATA3 (CLV3), a peptide hormone that regulates stem cell fate in meristems, is highly expressed in the pedicel abscission zone (AZ) in response to low light in tomato (Solanum lycopersicum). SlCLV3 knockdown and knockout lines exhibit delayed low light-induced flower drop. The receptor kinases SlCLV1 and BARELY ANY MERISTEM1 function in the SlCLV3 peptide-induced low light response in the AZ to decrease expression of the transcription factor gene WUSCHEL (SlWUS). DNA affinity purification sequencing identified the transcription factor genes KNOX-LIKE HOMEDOMAIN PROTEIN1 (SlKD1) and FRUITFULL2 (SlFUL2) as SlWUS target genes. Our data reveal that low light reduces SlWUS expression, resulting in higher SlKD1 and SlFUL2 expression in the AZ, thereby perturbing the auxin response gradient and causing increased ethylene production, eventually leading to the initiation of abscission. These results demonstrate that the SlCLV3-SlWUS signaling pathway plays a central role in low light-induced abscission by affecting auxin and ethylene homeostasis.

中文翻译：

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SlCLV3-SlWUS 模块在弱光诱导的番茄花脱落中调节生长素和乙烯稳态。

弱光胁迫引起的花和果实过早脱落会严重降低作物产量。然而，这种器官脱落的潜在分子机制尚不完全清楚。在这里，我们发现编码 CLAVATA3 (CLV3) 的基因 (SlCLV3)，一种调节分生组织中干细胞命运的肽激素，在番茄 (Solanum lycopersicum) 的花梗脱落区 (AZ) 中高表达，以响应弱光。SlCLV3 敲低和敲除品系表现出延迟的低光诱导落花。受体激酶 SlCLV1 和几乎任何 MERISTEM1 在 SlCLV3 肽诱导的 AZ 弱光反应中发挥作用，以减少转录因子基因 WUSCHEL (SlWUS) 的表达。DNA亲和纯化测序鉴定出转录因子基因KNOX-LIKE HOMEDOMAIN PROTEIN1 (SlKD1)和FRUITFULL2 (SlFUL2)作为SlWUS靶基因。我们的数据表明，弱光会降低 SlWUS 表达，导致 AZ 中 SlKD1 和 SlFUL2 表达升高，从而扰乱生长素响应梯度并导致乙烯产生增加，最终导致脱落的开始。这些结果表明，SlCLV3-SlWUS 信号通路通过影响生长素和乙烯稳态在弱光诱导的脱落中发挥核心作用。