Genome-Wide Profiling of bZIP Transcription Factors and FocbZIP11's Impact on Fusarium TR4 Pathogenicity

The basic leucine zipper (bZIP) transcription factor (TF) family performs diverse functions in fungal processes, including vegetative growth, nutrient utilization, stress responses, and invasion. Despite their importance, little is known about the bZIP members in Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), a highly virulent banana pathogen. In this study, we systematically identified 17 bZIPs distributed across 10 Foc TR4 chromosomes and classified them into four types based on their protein sequences. Phylogenetic analysis of fungal bZIP TFs revealed that the FocbZIP proteins cluster into 12 groups shared across fungal species. A cis-element analysis showed that each bZIP promoter contains at least one type of stress response-related element. Furthermore, RNA-seq and RT-qPCR analyses of FocbZIP gene expression patterns demonstrated that these genes may serve distinct roles during infection. Notably, the deletion of FocbZIP11 led to reduced vegetative growth, heightened sensitivity to osmotic, oxidative, and cell wall stresses, and diminished virulence toward banana plantlets. Overall, our findings indicate that FocbZIP11 plays a critical role in growth, abiotic stress responses, and virulence in Foc TR4. This study provides a foundation for the further functional characterization of FocbZIP genes, and FocbZIP11 might serve as a promising target for RNA-based biopesticide control of FWB.