Analysis of the SlRAF-like B gene family in tomato and the molecular mechanism of SlRAF7 in regulating cold stress resistance.

Abstract

The SlRAF-like B gene family is crucial for the regulation of seed dormancy and response to osmotic stress. In this research, a bioinformatics approach was employed to identify a total of 18 members belonging to the SlRAF-like B gene family within the tomato genome. Phylogenetic analysis has categorized the identified SlRAF-like B genes into four distinct groups, revealing significant differences in conserved motifs and gene structure among the proteins within each cluster. Promoter sequence analysis revealed abundant stress, hormone, and light response elements, suggesting the involvement of SlRAF-like B genes in cold stress responses. RT-qPCR analysis showed that most SlRAF-like B genes are induced by cold stress. A knockout mutant of the SlRAF7 gene, belonging to the SlRAF-like B3 group, was generated and tested under normal and cold stress, demonstrating that SlRAF7 positively regulates cold resistance in tomato plants. Further analysis of antioxidant enzyme activities, expression of related genes, and key cold response genes (ICE1, CBFs, and COR genes) in different genotypes suggests that SlRAF7 may enhance cold resistance by modulating the antioxidant enzyme pathway and the CBF signaling pathway. This study provides initial insights into the physiological and molecular mechanisms that underlie cold stress tolerance in tomato, with a particular focus on the role of the SlRAF7 gene.