TkMYB7 Coordinates Jasmonate and Ethylene Signaling to Regulate Natural Rubber Biosynthesis in Taraxacum kok-saghyz

Russian dandelion (Taraxacum kok-saghyz Rodin, TKS) is a natural rubber (NR)-producing species whose roots contain 3% to 27% NR, underscoring its considerable research and economic significance. The myeloblastosis (MYB) transcription factor family, one of the largest in plants, plays pivotal roles in metabolic regulation, stress responses, and various growth and developmental processes. To identify key MYB transcription factors involved in hormone-induced rubber biosynthesis, we conducted homology-based and bioinformatic analyses to characterize 268 MYB family proteins in the TKS genome. Utilizing transcriptome data from jasmonic acid (JA) and ethylene (ET) treatments, we screened and shortlisted 10 candidate TkMYB transcription factors. Through tissue-specific expression profiling, TkMYB7 was selected as the primary candidate. We confirmed that promoter analysis combined with yeast one-hybrid assays confirmed that TkMYB7 directly binds to and regulates the expression of acetyl-CoA acetyltransferase (TkACAT5), a key enzyme in the mevalonate (MVA) pathway. Furthermore, heterologous overexpression of TkMYB7 in Arabidopsis thaliana significantly enhanced seed germination and root development. These findings identify TkMYB7 as a novel transcriptional regulator linking JA and ET signaling pathways to rubber biosynthesis in TKS, representing a promising target for the genetic improvement of rubber yield.