Epigenetically regulated MYB–Nudix/TPS cascade drives geraniol biosynthesis in tea plants
Geraniol is a key floral aroma compound in tea and preferentially accumulates in young leaves for premium tea production, yet the molecular basis underlying its leaf position–dependent distribution remains unclear. Here, metabolomic profiling across successive leaf positions uncovered geranyl monophosphate (GP) abundance significantly positively correlated with geraniol accumulation. Functional analyses combining in vitro enzyme assays and metabolic profiling of transgenic tea plants identified CsNudix1-cyto as a key hydrolase responsible for GP accumulation, and geraniol production. Integrative transcriptome analyses and molecular validation revealed that CsMYB88 and CsMYB200 directly activate both CsNudix1-cyto and CsTPS1, thereby promoting geraniol biosynthesis in young leaves. Intriguingly, CsMYB200 activates the CsMYB88 promoter, forming a MYB cascade amplifying downstream geraniol biosynthetic genes. Furthermore, bisulfite sequencing demonstrated developmental stage–specific hypermethylation of a CpG island in the CsMYB200 promoter in mature leaves, which is associated with coordinated repression of CsMYB200, CsMYB88, CsNudix1-cyto, and CsTPS1, and decline in geraniol accumulation. Together, these findings establish a Nudix/TPS-mediated biosynthetic pathway controlled by a MYB transcriptional cascade and epigenetic regulation, providing a mechanistic framework for leaf position–dependent aroma formation in tea plants.