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

Taraxacum kok-saghyz (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 TkCPT/CPTL family, with eight CPT and two CPTL 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 Taraxacum mongolicum. Collinearity analyses showed that fragment duplications were the primary factor of amplification in the TkCPT/CPTL gene family. Induced by ethylene and methyl jasmonate hormones, the expression levels of most genes increased, with significant increases in the expression levels of TkCPT5 and TkCPT6. Our results provide a theoretical basis for elucidating the role of the TkCPT/CPTL gene family in the mechanism of natural rubber synthesis and lay a foundation for molecular breeding of T. kok-saghyz and candidate genes for regulating natural rubber biosynthesis in the future.