The CBL-CIPK Network Integrates Calcium and ABA Signaling to Mediate Drought Adaptation in Asparagus cochinchinensis

Background Asparagus cochinchinensis (Lour.) Merr. ( A. cochinchinensis ) is a precious traditional Chinese medicinal herb with significant economic value. However, its cultivation is severely constrained by environmental stresses, particularly drought. The Calcineurin B-Like (CBL) and CBL-Interacting Protein Kinase (CIPK) network constitutes a crucial calcium sensor system that decodes stress-induced Ca ²⁺ signatures in plants. Despite its importance, the molecular architecture and functional roles of the CBL-CIPK network in A. cochinchinensis remain largely uncharacterized. Results In this study, we generated a high-quality full-length transcriptome of A. cochinchinensis using PacBio Single-Molecule Real-Time (SMRT) sequencing, yielding 52,042 non-redundant transcripts. Based on this resource, we identified 35 AcCIPK and 13 AcCBL genes. Phylogenetic analysis revealed high conservation between AcCIPK24/AcCIPK23 and their Arabidopsis orthologs, while also uncovering species-specific alternative splicing events, including a truncated isoform of AcCIPK24.5 . Yeast two-hybrid assays confirmed a specific physical interaction between AcCBL10 and AcCIPK24. Expression profiling demonstrated that these genes exhibit tissue-specific and temporal responses to drought stress. Notably, while both genes were downregulated in roots and stems under drought, AcCBL10 was significantly upregulated in cladodes, suggesting complex regulatory mechanisms. Furthermore, hormone analysis revealed that drought stress induced endogenous ABA accumulation, and exogenous ABA application not only accelerated this peak but also enhanced the expression of AcCBL10 and AcCIPK24.5 , indicating a positive feedback loop between calcium signaling and ABA pathways. Conclusion This study provides the first comprehensive functional characterization of the CBL-CIPK network in A. cochinchinensis . The specific interaction between AcCBL10 and AcCIPK24 , coupled with the crosstalk between calcium signaling and ABA pathways, highlights a key molecular mechanism underlying drought adaptation in this medicinal plant.