Narrow leaf 1 (NAL1) plays an important role in plant branching, while little is known about the roles of this gene in petunias. In this study, PhNAL1b was cloned from Petunia×hybrida cv. Mitchell Diploid, with a total length of 1 767 bp, encoding a protein composed of 588 amino acid residues and containing the peptidase S64 domain. The PhNAL1b promoter region contained several elements involved in the responses to auxin, jasmonic acid, abscisic acid, and light. The expression analysis showed that PhNAL1b had the highest expression level in roots and the lowest expression level in flowers, and its transcription could be inhibited by decapitation and cytokinin. The subcellular localization analysis showed that PhNAL1b was located in the nucleus and was a nuclear protein. Virus-induced gene silencing was employed to downregulate the expression of PhNAL1b, which resulted in significant increases in branch number and plant height. The results indicated that PhNAL1b played an important role in regulating the branching of petunias. This study lays a foundation for revealing the mechanism of NAL1 in regulating branch development and provides genetic resources for plant architecture improvement.
Petunia/growth & development* ; Plant Proteins/metabolism* ; Diploidy ; Gene Expression Regulation, Plant ; Cloning, Molecular ; Promoter Regions, Genetic