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Article|23 Mar 2022|OPEN
Functional analysis of the ScAG and ScAGL11 MADS-box transcription factors for anthocyanin biosynthesis and bicolour pattern formation in Senecio cruentus ray florets
Fangting Qi1 ,† , Yuting Liu1 ,† , Yiliu Luo1 , Yumeng Cui1 , Chenfei Lu1 , Hao Li1 , He Huang1 , and Silan Dai,1 ,
1Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Education Ministry, School of Landscape Architecture, Beijing Forestry University, Beijing, 100083, China
*Corresponding author. E-mail: 101navy@163.com,silandai@sina.com
Both authors contributed equally to the study.

Horticulture Research 9,
Article number: uhac071 (2022)
doi: https://doi.org/10.1093/hr/uhac071
Views: 55

Received: 11 Aug 2021
Accepted: 07 Mar 2022
Published online: 23 Mar 2022

Abstract

Cineraria (Senecio cruentus) is an ornamental plant with pure colour and bicolour cultivars, widely used for landscaping. Anthocyanin biosynthesis influences coloration patterns in cineraria. However, how anthocyanins accumulate and distribute in cineraria is poorly understood. This study investigated the molecular mechanisms underlying anthocyanin biosynthesis and bicolour formation in cineraria using pure colour and bicolour cultivars. Transcriptome and gene expression analysis showed that five genes, ScCHS2ScF3H1ScDFR3ScANS, and ScbHLH17, were inhibited in the white cultivar and colourless regions of bicolour cultivars. In contrast, two MADS-box genes, ScAG and ScAGL11, showed significantly higher expression in the colourless regions of bicolour cultivars. ScAG and ScAGL11 were localized in the nucleus and co-expressed with the bicolour trait. Further functional analysis verified that ScAG inhibits anthocyanin accumulation in tobacco (Nicotiana tabacum). However, virus-induced gene silencing (VIGS) experiments showed that silencing of ScAG and ScAGL11 increases anthocyanin content in cineraria leaves. Similar results were observed when ScAG and ScAGL11 were silenced in the cineraria capitulum, accompanied by the smaller size of the colourless region, specifically in the ScAG/ScAGL11-silenced plants. The expression of ScCHS2ScDFR3, and ScF3H1 increased in silenced cineraria leaves and capitulum. Furthermore, yeast two-hybrid and bimolecular fluorescence complementation experiments demonstrated that ScAG interacts with ScAGL11. Moreover, ScAG directly inhibited the transcription of ScF3H1 while ScAGL11 inhibited ScDFR3 expression by binding to their promoters separately. The findings reported herein indicate that ScAG and ScAGL11 negatively regulate anthocyanin biosynthesis in cineraria ray florets, and their differential expression in ray florets influences the bicolour pattern appearance.