Background: GDSL esterases/lipases are a large protein subfamily defined by the distinct GDSL motif, and play important roles in plant development and stress responses. However, few studies have reported on the role of GDSLs in the growth and development of axillary buds. This work aims to identify the GDSL family members in tobacco and explore whether the NtGDSL gene contributes to development of the axillary bud in tobacco. Results: One hundred fifty-nine GDSL esterase/lipase genes from cultivated tobacco (Nicotiana tabacum) were identified, and the dynamic changes in the expression levels of 93 of these genes in response to topping, as assessed using transcriptome data of topping-induced axillary shoots, were analysed. In total, 13 GDSL esterase/lipase genes responded with changes in expression level. To identify genes and promoters that drive the tissue-specific expression in tobacco apical and axillary buds, the expression patterns of these 13 genes were verified using qRT-PCR. GUS activity and a lethal gene expression pattern driven by the NtGDSL127 promoter in transgenic tobacco demonstrated that NtGDSL127 is specifically expressed in apical buds, axillary buds, and flowers. Three separate deletions in the NtGDSL127 promoter demonstrated that a minimum upstream segment of 235 bp from the translation start site can drive the tissue-specific expression in the apical meristem. Additionally, NtGDSL127 responded to phytohormones, providing strategies for improving tobacco breeding and growth. Conclusion: We propose that in tobacco, the NtGDSL127 promoter directs expression specifically in the apical meristem and that expression is closely correlated with axillary bud development.

The release and outgrowth of axillary buds are essential parts of the process of shoot branching in plants, but knowledge of the underlying regulatory mechanisms remains limited. Analysis of mab1‐D , a tobacco mutant with a greater number of axillary branches, showed that the mutant phenotype resulted from positive modulation of axillary buds release and outgrowth. TAIL‐PCR and co‐separation analyses suggested that NtMAB1‐S1 , a member of the Related to ABI3/VP1 ( RAV ) subfamily that was highly expressed in the base of axillary buds, was associated with the mutant phenotype. Phenotypic analyses of mab1‐D overexpression, knockdown, knockout and complementation lines demonstrated that NtMAB1‐S1 was a positive regulator of axillary buds release and outgrowth. NtMAB1‐S1 accelerated these processes through transcriptional repression via the B3 repression domain. RNA‐sequencing analysis revealed that NtMAB1‐S1 was involved in the trehalose‐6‐phosphate and gibberellin metabolism pathways. Moreover, NtMAB1‐S1 enhanced the release and outgrowth of axillary buds by directly repressing transcription of NtTPPF , a trehalose‐6‐phosphate phosphatase, and NtGA2ox8 , a gibberellin oxidase. NtMAB1‐S1 thus plays a pivotal role in regulating the release and outgrowth of axillary buds and is a potential target for genetic interventions aimed at shaping ideal plant architecture.