Genome-Wide Analysis of the Cis-Prenyltransferase (CPT) Gene Family in <i>Taraxacum kok-saghyz</i> Provides Insights into Its Expression Patterns in Response to Hormonal Treatments

<i>Taraxacum kok-saghyz</i> (TKS) is a natural rubber (NR)-producing plant with great development prospects. Accurately understanding the molecular mechanism of natural rubber biosynthesis is of great significance. Cis-prenyltransferase (CPT) and cis-prenyltransferase-like (CPTL) proteins catalyze the elongation of natural rubber molecular chains and play an essential role in rubber biosynthesis. In this study, we performed a genome-wide identification of the <i>TkCPT</i>/<i>CPTL</i> family, with eight <i>CPT</i> and two <i>CPTL</i> members. We analyzed the gene structures, evolutionary relationships and expression patterns, revealing five highly conserved structural domains. Based on systematic evolutionary analysis, CPT/CPTL can be divided into six subclades, among which the family members are most closely related to the orthologous species <i>Taraxacum mongolicum.</i> Collinearity analyses showed that fragment duplications were the primary factor of amplification in the <i>TkCPT/CPTL</i> gene family. Induced by ethylene and methyl jasmonate hormones, the expression levels of most genes increased, with significant increases in the expression levels of <i>TkCPT5</i> and <i>TkCPT6</i>. Our results provide a theoretical basis for elucidating the role of the <i>TkCPT</i>/<i>CPTL</i> gene family in the mechanism of natural rubber synthesis and lay a foundation for molecular breeding of <i>T. kok-saghyz</i> and candidate genes for regulating natural rubber biosynthesis in the future.