Genome-wide analysis of ABF gene family in lettuce ( Lactuca sativa L.) reveals the negative roles of LsABF1 in thermally induced bolting

High-temperature-induced early bolting poses a pressing challenge in annual leaf lettuce cultivation. ABF transcription factors, or ABA-responsive element binding factors, are crucial components of the ABA signalling pathway. In this study, we identified 8 members of the ABF gene family in leaf lettuce, categorising them into groups A, B, and C through phylogenetic analysis. All LsABFs exhibited a conserved domain, RMIKNRESAARSRARKQAY (Bzip_plant_BZIP46), as revealed by multiple sequence alignment. A total of 1242 cis-acting elements were detected, with 323 elements screened. Predictive analysis indicated 304 phosphorylation sites. Expression patterns of LsABFs were similar, peaking on the 8th day, implicating their role in bolting. Silencing LsABF1 positively impacted lettuce bolting, signifying its regulatory potential. This study establishes a theoretical foundation for comprehending the molecular mechanisms governing ABF genes in high-temperature-induced bolting in leaf lettuce.