Foliar-applied methanol promotes root growth and rubber production in Taraxacum kok-saghyz

Taraxacum kok-saghyz L.E. Rodin (TKS) has been identified as a promising alternative source of natural rubber. Enhancing rubber yield has been the primary focus of research aimed at establishing TKS as a competitive rubber crop. In this study, we demonstrate for the first time that foliar application of 25 % methanol, but not irrigation, significantly increases root biomass and rubber content in both laboratory- and field-grown TKS plants. Transcript analysis using qRT-PCR revealed the upregulation of several rubber biosynthetic genes, notably those associated with the mevalonate pathway and cis-prenyltransferase genes, in response to methanol treatment. These results were largely consistent with our RNA-seq data, which also provided molecular evidence for the enhanced growth of methanol-treated TKS. Our study offers novel insights into the molecular basis underlying methanol-induced rubber biosynthesis and growth promotion. These findings establish foliar methanol application as a simple and effective strategy to enhance rubber yield in TKS and potentially in other alternative rubber-producing crops.