PhSPEAR1 Participates in Regulating the Branch Development of Petunia

Petunia hybrida is an economically important ornamental plant species. Branching in ornamental plants is closely associated with their ornamental traits, and branching is a significant agronomic trait in petunia, which shapes plant architecture and production cost. Although there are few studies regarding the involvement of the SPEAR genes in lateral branch development, they are known to regulate the development of plant organs. The PhSPEAR1 gene in petunia, an ortholog of Arabidopsis SPEAR1, was isolated for study. According to the results of real-time quantitative PCR (qRT-PCR), PhSPEAR1 was primarily expressed in the roots. The fluorescence signal indicated that PhSPEAR1 was localized in the nucleus and cytoplasm. An increase in PhSPEAR1 expression was induced by cytokinin or decapitation. Overexpression of PhSPEAR1 increased lateral branches in Arabidopsis. Based on our findings, PhSPEAR1 participates significantly in the regulation of branch number in petunia.