Identification and analysis of the metacaspase gene family in tomato

Metacaspases play critical roles in developmentally regulated and environmentally induced programmed cell death in plants. In this study, we systematically identified and analyzed metacaspase gene family in tomato (Solanum lycopersicum). The results illustrated that tomato possesses eight metacaspase genes (SlMC1-8) located on chromosomes 1, 3, 5, 9, and 10. SlMC1-6 belonged to type I metacaspases and had 5 exon/4 intron structures. SlMC7 and 8 were type II metacaspases and had 2 and 3 exons, respectively. Expression analysis revealed distinct expression patterns of SlMCs in various tomato tissues. Cis-regulatory element prediction showed that there were many hormone- and stress-related cis-regulatory elements in SlMCs promoter regions. Quantitative real-time PCR analysis further demonstrated that most of the SlMCs were regulated by drought, cold, salt, methyl viologen, and ethephon treatments. This study provides insights into the characteristics of SlMC genes and laid the foundation for further functional analysis of these genes in tomato.