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Article|16 Feb 2023|OPEN
A petunia transcription factor, PhOBF1, regulates flower senescence by modulating gibberellin biosynthesis
Xiaotong Ji1 ,† , Ziwei Xin1 ,† , Yanping Yuan1 , Meiling Wang1 , Xinyi Lu1 , Jiaqi Li1 , Yanlong Zhang1 , Lixin Niu1 , Cai-Zhong Jiang2,3 , Daoyang Sun,1 ,
1College of Landscape Architecture and Arts, Northwest A&F University, Yangling, Shaanxi 712100, China
2Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
3Crops Pathology and Genetics Research Unit, USDA-ARS, Davis, CA 95616, USA
*Corresponding author. E-mail:
Both authors contributed equally to the study.

Horticulture Research 10,
Article number: uhad022 (2023)
Views: 241

Received: 24 Oct 2022
Accepted: 06 Feb 2023
Published online: 16 Feb 2023


Flower senescence is commonly enhanced by the endogenous hormone ethylene and suppressed by the gibberellins (GAs) in plants. However, the detailed mechanisms for the antagonism of these hormones during flower senescence remain elusive. In this study, we characterized one up-regulated gene PhOBF1, belonging to the basic leucine zipper transcription factor family, in senescing petals of petunia (Petunia hybrida). Exogenous treatments with ethylene and GA3 provoked a dramatic increase in PhOBF1 transcripts. Compared with wild-type plants, PhOBF1-RNAi transgenic petunia plants exhibited shortened flower longevity, while overexpression of PhOBF1 resulted in delayed flower senescence. Transcript abundances of two senescence-related genes PhSAG12 and PhSAG29 were higher in PhOBF1-silenced plants but lower in PhOBF1-overexpressing plants. Silencing and overexpression of PhOBF1 affected expression levels of a few genes involved in the GA biosynthesis and signaling pathways, as well as accumulation levels of bioactive GAs GA1 and GA3. Application of GA3 restored the accelerated petal senescence to normal levels in PhOBF1-RNAi transgenic petunia lines, and reduced ethylene release and transcription of three ethylene biosynthetic genes PhACO1PhACS1, and PhACS2. Moreover, PhOBF1 was observed to specifically bind to the PhGA20ox3 promoter containing a G-box motif. Transient silencing of PhGA20ox3 in petunia plants through tobacco rattle virus-based virus-induced gene silencing method led to accelerated corolla senescence. Our results suggest that PhOBF1 functions as a negative regulator of ethylene-mediated flower senescence by modulating the GA production.