Tendril morphogenesis is regulated by a CsaTEN–CsaUFO module in cucumber

Abstract

Summary Tendril is a morphological innovation during plant evolution, which provides the plants to obtain climbing ability. However, the tendril morphogenesis is poorly understood. A novel tendril morphogenesis defective mutant (tmd1) was identified in cucumber. The apical part of tendril was replaced by a leaf blade in tmd1 mutant, and it lost the climbing ability. Map‐based cloning, qPCR detection, bioinformatic analysis, yeast one‐hybrid assay, electrophoretic mobility shift assay, and luciferase assay were used to explore the molecular mechanism of CsaTMD1 in regulating tendril morphogenesis. CsaUFO was the candidate causal gene, and a fragment deletion within promoter impaired CsaUFO expression in tmd1 mutant. A conserved motif 1, which harbored two putative TCP transcription factor binding sites, was located within this deleted fragment. CsaTEN directly bound the motif 1 and positively regulated CsaUFO, and mutation in motif 1 removed this regulation. Our work shows a CsaTEN–CsaUFO module in regulating tendril morphogenesis, indicating that evolution of tendril in cucumber due to simply drive of CsaUFO by CsaTEN in tendril. Additionally, the conserved motif 1 provides a strategy for engineering tendril‐less Cucurbitaceae crops.