Functional Analysis of the CsTFL1c Gene in Regulating Lateral Branch Number in Cucumber

To investigate the function of the CsTFL1c gene in cucumber lateral branch development and provide a theoretical basis and genetic resources for cucumber plant architecture improvement. Bioinformatics methods were used to analyze the phylogenetic relationship and physicochemical properties of CsTFL1c. Cucumber inbred line XTMC (a low-branching genotype) was used as the genetic transformation recipient. Agrobacterium-mediated transformation was performed to obtain T0 generation CsTFL1c overexpression transgenic plants, from which 3 lines with stably heritable phenotypes were selected. RNA sequencing (RNA-seq) was conducted to compare the transcriptomes of overexpression lines and the control line, aiming to reveal the underlying molecular regulatory network. A total of 4 TFL1 homologous genes were identified in the cucumber genome. Phylogenetic analysis showed that CsTFL1c was most closely related to AtTFL1 and clustered in the same clade. Phenotypic identification revealed that the number of lateral branches in CsTFL1c overexpression lines was significantly higher than that in the control line. Transcriptomic analysis identified 3090 differentially expressed genes (DEGs). Further analysis indicated that the expression levels of multiple transcription factors involved in lateral branch development and auxin-related genes were significantly altered. CsTFL1c plays a positive regulatory role in cucumber lateral branch initiation, and its function may be achieved by regulating the expression of a series of lateral branch-related transcription factors and auxin-related genes.