PhCYP724B1 positively regulates shoot branching

Abstract Background: Petunia hybrida is an important ornamental plant, and branch regulation is of great significance in its cultivation. Results: We isolated the homologous gene of CYP724B1 from Petunia × hybrida cv 'Mitchell Diploid', and named PhCYP724B1. Expression analysis revealed that PhCYP724B1 was expressed highest in buds, while lowest in flowers. The expression level of PhCYP724B1 was higher in the petunia variety with more branches, while lower in variety with fewer branches. Subcellular localization assays demonstrated that PhCYP724B1 protein was localized on the endoplasmic reticulum. Furthermore, overexpression of PhCYP724B1 in transgenic Arabidopsis and petunia plants both enhanced shoot branching. In contrast, RNAi of PhCYP724B1 in petunia resulted in a significantly inhibited shoot branching phenotype. Conclusions: Taken together, the results denote new insights into the important role of PhCYP724B1 in regulating petunia shoot branching.