Cloning of the GPCR-type G protein gene SikCOLD1 from Saussurea involucrata and functional validation and mechanistic analysis of its chilling tolerance in overexpressed processing tomato

Chilling stress is a major abiotic constraint limiting the production of processing tomato, and the identification of superior chilling-tolerance genes and elucidation of their regulatory mechanisms are of great significance for genetic improvement of tomato stress resistance. COLD1 (Chilling tolerance divergence 1) is a key cold sensor protein in plants that plays a central role in cold signal perception and response. However, the chilling-tolerance function and downstream regulatory network of SikCOLD1 , derived from the alpine extreme plant Saussurea involucrata, remain largely unexplored in processing tomato. In this study, SikCOLD1 -overexpressing processing tomato lines (OE) and the wild-type cultivar Riegel 87-5 (WT) were used as experimental materials and subjected to chilling stress at 4°C for 48 h. By integrating physiological and biochemical analyses, transcriptome sequencing, weighted gene co-expression network analysis (WGCNA), protein–protein interaction (PPI) network analysis, and qRT-PCR validation, we systematically investigated the physiological basis and molecular regulatory mechanisms underlying SikCOLD1 -mediated chilling tolerance in tomato.