The fruit glossiness locus, dull fruit (D) encodes a C2H2 type zinc finger transcription factor CsDULL in cucumber (Cucumis sativus L.)

Authors: ZHAI, XIULING - China Agricultural University; WU, HAOYIN - China Agricultural University; WANG, YARU - China Agricultural University; ZHANG, ZHONGREN - China Agricultural University; SHAN, LI - China Agricultural University; ZHAO, XI - China Agricultural University; WANG, RUIJIA - China Agricultural University; LIU, CHANG - China Agricultural University; Weng, Yiqun; WANG, YING - China Agricultural University; LIU, XINGWANG - China Agricultural University; REN, HUAZHONG - China Agricultural University

Submitted to: Horticulture Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2022
Publication Date: 7/2/2022
Citation: Zhai, X., Wu, H., Wang, Y., Zhang, Z., Shan, L., Zhao, X., Wang, R., Liu, C., Weng, Y., Wang, Y., Liu, X., Ren, H. 2022. The fruit glossiness locus, dull fruit (D) encodes a C2H2 type zinc finger transcription factor CsDULL in cucumber (Cucumis sativus L.). Horticulture Research. 2022, 9: uhac146. https://doi.org/10.1093/hr/uhac146.
DOI: https://doi.org/10.1093/hr/uhac146

Interpretive Summary: Background: Fruit glossiness is an important external fruit quality trait for fresh consumed cucumber fruit affecting its marketability. Dull fruit appearance is mainly controlled by a single gene D for dull fruit and d for glossy fruit, but the molecular mechanisms controlling fruit glossiness is unknown. Major findings: In this study, we conducted map-based cloning of the D gene locus in cucumber and identified a candidate gene that encodes transcription factor protein (CsDULL). Normal cucumber has dull fruit looking, but in the glossy fruit plant, a large piece of DAN (4895 base pairs) was missing from this gene. The CsDULL gene has high expression in the peel of cucumber fruit, and its expression level is positively correlated with the accumulation of cutins and waxes in the peel. From multiple experiments, we identified two genes potentially targeted by the CsDULL transcription factor for regulation of cutin and wax biosynthesis/transportation. The possibility that CsDULL controls both fruit glossiness and wart development in cucumber is discussed. Who cares Our work advances our understanding of regulatory mechanisms of fruit epidermal traits, and provides useful tool for molecular breeding to improve external fruit quality in cucumber.

Technical Abstract: Fruit glossiness is an important external fruit quality trait for fresh consumed cucumber fruit affecting its marketability. Dull fruit appearance is mainly controlled by a single gene, D (for dull fruit) that is dominant to glossy fruit (dd), but the molecular mechanisms controlling fruit glossiness is unknown. In the present study, we conducted map-based cloning of the D locus in cucumber and identified a candidate gene (Csa5G577350) that encodes a C2H2 type zinc finger transcription factor, CsDULL. A 4895bp deletion including the complete loss of CsDULL resulted in glossy fruit. CsDULL is highly expressed in the peel of cucumber fruit, and its expression level is positively correlated with the accumulation of cutins and waxed in the peel. Through transcriptome analysis, yeast one-hybrid and dual-luciferase assays, we identified two genes potentially targeted by CsDULL for regulation of cutin and wax biosynthesis/transportation that included CsGPAT4 and CsLTPG1. The possibility that CsDULL controls both fruit glossiness and wart development in cucumber is discussed. The present work advances our understanding of regulatory mechanisms of fruit epidermal traits, and provides useful tool for molecular breeding to improve external fruit quality in cucumber.