Genome-Wide Analysis of the TIFY Gene Family in Three Cymbidium Species and Its Response to Heat Stress in Cymbidium goeringii

The TIFY family is a plant-specific gene family that is involved in regulating a variety of plant processes, including developmental and defense responses. The Cymbidium species have certain ornamental and ecological value. However, the characteristics and functions of TIFY genes in Cymbidium remain poorly understood. This study conducted a genome analysis of the TIFY gene family in Cymbidium goeringii, C. ensifolium, and C. sinense and investigated their physicochemical properties, phylogenetic relationships, gene structures, and expression patterns under heat stress in C. goeringii. C. goeringii (26), C. ensifolium (19), and C. sinense (21). A total of 66 TIFY genes were identified, and they were classified into four subfamilies (JAZ, ZML, PPD, and TIFY) based on their systematic evolutionary relationships. Sequence analysis showed that TIFYs contained a conserved TIFY domain and that genes within the same subfamily had structural similarity. Analysis of cis-regulatory elements revealed that these genes contain numerous light-responsive elements and stress-responsive elements. We subjected C. goeringii (16 h light/8 h dark) to 24 h of 38 °C high-temperature stress in a climate chamber. Additionally, results from RT-qPCR experiments showed that under heat stress, the expression levels of eight genes in C. goeringii show significant differences. Among them, the JAZ subfamily exhibited the strongest response to heat stress, initially showing upregulation followed by a downregulation trend. In conclusion, this study investigated the role of TIFY genes in three Cymbidium species, providing insights into C. goeringii under heat stress.