Cucumber glossy fruit 1 (CsGLF1) encodes the zinc finger protein 6 that regulates fruit glossiness by enhancing cuticular wax biosynthesis

Cucumber glossiness is an important visual quality trait that affects consumer choice. Accumulating evidence suggests that glossy trait is associated with cuticular wax accumulation. However, the molecular genetic mechanism controlling cucumber glossiness remains largely unknown. Here, we report the map-based cloning and functional characterization of CsGLF1, a locus that determines the glossy trait in cucumber. CsGLF1 encodes a homolog of the Cys(2)His(2)-like fold group (C2H2) -type zinc finger protein 6 (ZFP6) and its deletion leads to glossier pericarp and decreased cuticular wax accumulation. Consistently, transcriptomic analysis demonstrated that a group of wax biosynthetic genes were downregulated when CsZFP6 was absent. Further, transient expression assay revealed that CsZFP6 acted as a transcription activator of cuticular wax biosynthetic genes. Taken together, our findings demonstrated a novel regulator of fruit glossiness, which will provide new insights into regulatory mechanism of fruit glossiness in cucumber.

Automated summary

Cucumber glossiness, an important visual quality trait for consumers, is associated with cuticular wax accumulation. This study identified CsGLF1 as the gene responsible for the glossy trait in cucumber. CsGLF1 encodes a C2H2-type zinc finger protein 6 (ZFP6) and its deletion results in glossier pericarp and reduced cuticular wax accumulation. Transcriptomic analysis revealed downregulation of wax biosynthetic genes in the absence of CsZFP6. Transient expression assays showed that CsZFP6 acts as a transcription activator for cuticular wax biosynthetic genes. These findings provide new insights into the regulatory mechanism of fruit glossiness in cucumber.