Fruit-Specific Promoters in Plants: Advances, Regulatory Mechanisms and Applications in Plant Biotechnology

Fruit-specific promoters (FSPs) are a class of regulatory DNA sequences that direct transgene expression exclusively in fruit tissues or during specific stages of fruit development. They are indispensable molecular tools in modern agricultural biotechnology, with broad applications in fruit quality improvement, nutritional enhancement, and shelf-life extension. By functioning as precise molecular switches that regulate fruit-specific gene expression, FSPs overcome the limitations of constitutive promoters and facilitate precision molecular breeding for fruit quality improvement. This review systematically summarizes recent advances in FSP research. First, based on their spatiotemporal expression patterns, FSPs are classified into four categories: immature fruit-specific, fruit ripening-specific, whole fruit development stage-specific, and dual-stage (immature fruit/ripening) promoters. Their origins, expression characteristics, and key cis-regulatory elements are comprehensively summarized. Second, the complex transcriptional regulatory network governing FSP activity is discussed from the perspectives of cis-regulatory elements, major transcription factor families (such as MADS-box and NAC proteins), and epigenetic regulation, including DNA methylation and histone modifications. Furthermore, recent advances in key methodologies, including promoter cloning, functional characterization, and CRISPR/Cas9-mediated precise editing of cis-regulatory elements, are reviewed, together with their applications in crop genetic improvement, plant molecular farming, and fundamental molecular biology research. Finally, this review highlights the major challenges limiting the application of FSPs, including the relatively weak transcriptional activity of natural promoters, insufficient tissue specificity, and limited cross-species applicability. Future perspectives are discussed, emphasizing the integration of artificial intelligence-assisted promoter design, high-throughput screening, and single-cell omics technologies to develop finely tunable synthetic promoters. These advances are expected to provide both a theoretical foundation and technical support for precision molecular breeding in fruit crops.