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Article|16 Dec 2015|OPEN
A basic helix-loop-helix transcription factor, PhFBH4, regulates flower senescence by modulating ethylene biosynthesis pathway in petunia
Jing Yin1,2 , Xiaoxiao Chang2,3 , Takao Kasuga4 and Mai Bui4 , Michael S Reid2 , Cai-Zhong Jiang,4 ,
1Department of Ornamental Horticulture, China Agricultural University, Beijing 100193, China
2Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
3Department of Horticulture, Northwest A&F University, Yangling, Shanxi, China
4Crops Pathology and Genetic Research Unit, United States Department of Agriculture, Agricultural Research Service, One Shields Avenue, Davis, CA 95616, USA
*Corresponding author. E-mail: cjiang@ucdavis.edu

Horticulture Research 2,
Article number: 59 (2015)
doi: https://doi.org/10.1038/hortres.2015.59
Views: 1078

Received: 23 Oct 2015
Revised: 07 Nov 2015
Accepted: 07 Nov 2015
Published online: 16 Dec 2015

Abstract

The basic helix-loop-helix (bHLH) transcription factors (TFs) play important roles in regulating multiple biological processes in plants. However, there are few reports about the function of bHLHs in flower senescence. In this study, a bHLH TF, PhFBH4, was found to be dramatically upregulated during flower senescence. Transcription of PhFBH4 is induced by plant hormones and abiotic stress treatments. Silencing of PhFBH4 using virus-induced gene silencing or an antisense approach extended flower longevity, while transgenic petunia flowers with an overexpression construct showed a reduction in flower lifespan. Abundance of transcripts of senescence-related genes (SAG12, SAG29) was significantly changed in petunia PhFBH4 transgenic flowers. Furthermore, silencing or overexpression of PhFBH4 reduced or increased, respectively, transcript abundances of important ethylene biosynthesis-related genes, ACS1 and ACO1, thereby influencing ethylene production. An electrophoretic mobility shift assay showed that the PhFBH4 protein physically interacted with the G-box cis-element in the promoter of ACS1, suggesting that ACS1 was a direct target of the PhFBH4 protein. In addition, ectopic expression of this gene altered plant development including plant height, internode length, and size of leaves and flowers, accompanied by alteration of transcript abundance of the gibberellin biosynthesis-related gene GA2OX3. Our results indicate that PhFBH4 plays an important role in regulating plant growth and development through modulating the ethylene biosynthesis pathway.