Comparative transcriptomics unveils the role of DELLA protein GAIP-B in cold tolerance of mango (Mangifera indica L.).

BACKGROUND: Cold stress severely limits the productivity and geographical distribution of mango, a tropical fruit crop of significant economic importance. We combined transcriptomic profiling and functional genomics to investigate the molecular mechanisms underlying cold tolerance in mango. RESULTS: Comparative analysis of the cold-tolerant Jinhuang (JH) and cold-sensitive Guiqi (GQ) cultivars identified 7,757 unique deferentially expressed genes (DEGs) were specifically altered in JH under cold stress, with significant enrichment in plant hormone signal transduction pathways. Notably, the DELLA protein GAIP-B (LOC123214451) was markedly upregulated in JH under cold stress. Functional validation through CRISPR/Cas9-mediated knockout and overexpression in Nicotiana benthamiana demonstrated that GAIP-B is both necessary and sufficient for cold tolerance. The knockout lines exhibit extreme cold sensitivity, reduced antioxidant enzyme activity, increased oxidative damage, and impaired osmotic adjustment. Conversely, the overexpression lines showed enhanced cold tolerance, with superior antioxidant capacity, maintenance of photosynthetic pigments, and increased soluble sugar accumulation. CONCLUSIONS: These findings establish GAIP-B as a central regulator that integrates antioxidant defense, photosynthetic protection, and osmotic adjustment in the cold stress response. This study provides valuable insight into molecular breeding strategies aimed at enhancing cold tolerance in mango and other economically important fruit crops.