College of Horticulture, Shenyang Agricultural University, Shenyang, 110866, China.
Key Laboratory of Protected Horticulture of Ministry of Education, Shenyang, China.
Plant Cell. 2022 Oct 27;34(11):4388-4408. doi: 10.1093/plcell/koac254.
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.
低光胁迫引发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未完全阐明。在这里，我们发现一个基因（SlCLV3）编码 CLAVATA3（CLV3），CLV3 是一种在分生组织中调节干细胞命运的肽激素，在番茄（Solanum lycopersicum）对低光的反应中，在花梗脱落区（AZ）中高度表达。SlCLV3 敲低和敲除系表现出延迟的低光诱导花脱落。受体激酶 SlCLV1 和 BARELY ANY MERISTEM1 在 SlCLV3 肽诱导的 AZ 中的低光反应中起作用，以降低转录因子基因 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 的靶基因。我们的数据表明，低光降低了 SlWUS 的表达，导致 AZ 中 SlKD1 和 SlFUL2 的表达增加，从而扰乱了生长素响应梯度并导致乙烯产量增加，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低光诱导的脱落中起核心作用。
