TkNACs Heterodimerization and Methyl Jasmonate Signaling Synergistically Mediate Root Development in Taraxacum kok-saghyz

Taraxacum kok-saghyz (T. kok-saghyz) is a promising alternative crop for natural rubber production, in which root development is closely associated with rubber synthesis; however, the molecular mechanisms governing root architecture formation remain largely unclear. NAC transcription factors play pivotal roles in plant root development, yet their functions in T. kok-saghyz have not been systematically investigated. In this study, a genome-wide analysis identified 34 NAC family members in T. kok-saghyz. Through transcriptomic analysis following methyl jasmonate (MeJA) treatment, 27 genes significantly responsive to MeJA signaling were screened. Sequence analysis revealed that all TkNAC proteins contain a conserved NAM domain. Subcellular localization assays confirmed that TkNAC16, TkNAC20, TkNAC23, and TkNAC30 are localized to the nucleus. Yeast two-hybrid and bimolecular fluorescence complementation assays demonstrated that TkNAC16/18/20/23/30 can form extensive heterodimers. Overexpression lines of T. kok-saghyz exhibited significantly increased root length, while leaf growth exhibited line- and stage-specific effects. Collectively, this study provides the first systematic identification of the NAC transcription factor family in T. kok-saghyz, elucidates their involvement in methyl jasmonate signaling responses, the construction of heterodimerization networks, and the positive regulation of root elongation. These findings provide crucial genetic resources and a theoretical basis for dissecting the molecular mechanisms underlying the coordinated improvement of root development and rubber yield in T. kok-saghyz.