Molecular Mechanisms in Responses to Combined Stresses in Strawberry

Strawberry is a globally important yet stress-sensitive crop, increasingly threatened by combined abiotic and biotic stresses. Unlike single stresses, combined stresses elicit unique, non-additive responses through complex signaling and gene regulatory networks. This review synthesizes current knowledge on the molecular mechanisms underlying strawberry responses to combined stresses, focusing on signal perception and transduction as well as gene regulation. We examine how combined stresses are perceived by membrane-localized sensors and calcium channels, and how these signals are transduced through MAPK (mitogen-activated protein kinase) cascades, CDPKs (calcium-dependent protein kinases), and hormonal crosstalk involving ABA (abscisic acid), JA (jasmonic acid), and ethylene. At the gene regulation level, we discuss the roles of key transcription factors (WRKY, NAC (NAM, ATAF1, ATAF2 and CUC2), GRAS (GAI-RGA-and-SCR), DREB (Dehydration-Responsive Element-Binding protein), bZIP (basic leucine zipper transcription factor), CAMTA (calmodulin-binding transcription activator), ARF (auxin response factor), and LAV (Leafy Cotyledon2-Abscisic Acid Insensitive3-Val)), transcriptional cascades, epigenetic regulation via DNA methylation, and post-transcriptional (miRNAs such as Fan-miR73) and post-translational (ubiquitination and phosphorylation) control mechanisms. The review also evaluates emerging mitigation strategies informed by these molecular insights, including genomic selection, and explores future directions such as CRISPR (clustered regularly interspaced short palindromic repeats)-based genome editing and multi-omics integration. We conclude that understanding the integrated signaling and gene regulatory networks is essential for developing climate-resilient strawberry cultivars capable of withstanding increasingly complex stress combinations.