Abstract
Tomato is a widely grown horticultural crop, and its growth process is often affected by high temperatures. Caseinolytic Protease B (ClpB), a homologous protein to heat shock protein 101 (HSP101), plays a vital role in plant heat adaptation and development. In this study, we identified six SlClpB genes in tomatoes, distributed across four chromosomes. Collinearity analysis revealed that the gene pairs SlClpB-2 and SlClpB-3A, as well as SlClpB-3C and SlClpB-12, resulted from segmental duplication events. Phylogenetic and motif analyses showed that ClpB proteins possess highly conserved domains across different species. We used RNA-seq data to analyze the expression patterns of the ClpB family. Among them, SlClpB-3A and SlClpB-12 exhibited increased expression in multiple tissues under heat stress. Specifically, SlClpB-2, SlClpB-3A, and SlClpB-3C were highly expressed in the fruit orange stage and in flower buds under heat treatment, while in seedlings, SlClpB-2 and SlClpB-3A exhibited heat-induced expression. Real-time quantitative fluorescent PCR (qRT-PCR) results showed that the expression of SlClpB-2 and SlClpB-3A was significantly increased under heat stress in the leaves and buds of Ailsa Craig, Micro-Tom, and M82. Overall, our findings provide valuable insights into the regulatory mechanisms of SlClpB genes in response to heat stress.