Diverse role of basic Helix-Loop-Helix (bHLH) transcription factor superfamily genes in the fleshy fruit-bearing plant species

The basic Helix-Loop-Helix (bHLH) superfamily is the most widespread family of transcription factors in eukaryotic organisms, which can activate the expression of genes by interacting with specific promoters in the genes. The bHLH transcription factors direct the development and metabolic process of plants, including flowering initiation and secondary metabolite production, by attaching to specific sites on their promoters. These transcription factors are essential for encouraging plant tolerance or the adjustment to harsh environmental conditions. The involvement of bHLH genes in anthocyanin formation in fleshy fruit-bearing plants, as well as the role of these genes in response to stimuli including drought, salt, and cold stress, are discussed in this article. New concepts and goals for the production of stress-tolerant fruit species are suggested. Furthermore, solid evidence for the critical role of bHLH genes in the growth and development, as well as anthocyanin biosynthesis in fleshy fruit plants, are also presented in this article. This review identifies several future research directions that can shed light on the roles of bHLH genes in fruit-bearing plants and will assist the use of these genes in efforts to breed fruit crop varieties that are more resistant to stress. Generally, there has been little research carried out on the role of bHLHs transcription factor family genes in fleshy fruit-bearing plant species and more in-depth studies are required to fully understand the diverse role of bHLH genes in these species.