Basic Leucine Zipper (bZIP) Transcription Factors as Biological Macromolecules Responded to Abiotic Stress and Secondary Metabolite Biosynthetic Pathways in Plants: A Comprehensive Review

Since abiotic stress is an unfavourable environmental factor that significantly affects plant growth and development, plants have evolved over time to adapt to these stresses, thereby enhancing their survival capabilities. As one of the largest transcription factor families in plants, bZIP transcription factors are involved in plant growth and development, plant hormone signalling transduction, secondary metabolism synthesis pathways, and responses to abiotic stress. Numerous studies have shown that bZIP transcription factors, upon activation by external environmental signals, can either act independently or through interactions with other proteins to bind to the A-box (TACGTA), the C-box (GACGTC), and the G-box (CACGTG) cis-acting elements in the promoter regions of downstream target non-biotic stress genes, thereby regulating the expression of downstream stress response genes and modulating plant tolerance to non-biotic stress as well as secondary metabolic pathways in plants. Additionally, bZIP transcription factors are involved in plant hormone signalling pathways in response to non-biotic stress. For example, abscisic acid, jasmonic acid, brassinosteroids, and salicylic acid. In this review, we discuss the structure, classification, and mechanisms of action of plant bZIP transcription factors, their roles in plant hormone regulation, and the mechanisms by which bZIP transcription factors respond to abiotic stresses such as drought, salt stress, high/low temperatures, nutrient deficiencies, heavy metal stress and light stress. Additionally, we summarise the role of bZIP transcription factors in regulating the biosynthesis of various secondary metabolites, such as flavonoids, terpenoids, alkaloids, phenolic acids and lignans. Finally, the role of bZIP transcription factors and non-coding RNAs (ncRNA) in enhancing tolerance to abiotic stress was discussed. In the future, we will focus on studying bZIP transcription factors as core regulators of downstream gene networks associated with abiotic stress to enhance plant tolerance to abiotic stress and improve crop yields, thereby addressing food security issues.