A petunia transcription factor, <i>PhOBF1</i>, regulates flower senescence by modulating gibberellin biosynthesis

Abstract Flower senescence is commonly enhanced by the endogenous hormone ethylene and suppressed gibberellins (GAs) in plants. However, detailed mechanisms for antagonism of these hormones during flower remain elusive. In this study, we characterized one up-regulated gene PhOBF1, belonging to basic leucine zipper transcription factor family, senescing petals petunia (Petunia hybrida). Exogenous treatments with GA3 provoked a dramatic increase PhOBF1 transcripts. Compared wild-type plants, PhOBF1-RNAi transgenic plants exhibited shortened longevity, while overexpression resulted delayed senescence. Transcript abundances two senescence-related genes PhSAG12 PhSAG29 were higher PhOBF1-silenced but lower PhOBF1-overexpressing Silencing affected expression levels few involved GA biosynthesis signaling pathways, as well accumulation bioactive GAs GA1 GA3. Application restored accelerated petal normal lines, reduced release three biosynthetic PhACO1, PhACS1, PhACS2. Moreover, was observed specifically bind PhGA20ox3 promoter containing G-box motif. Transient silencing through tobacco rattle virus-based virus-induced method led corolla Our results suggest that functions negative regulator ethylene-mediated modulating production.