Single-nucleus transcriptomics reveals laticifer-specific transcriptional programs and triterpenoid-rubber metabolic coordination in Euphorbia lathyris L

Laticifers are specialized secretory cells that synthesize and store latex and provide a model for studying cellular specialization in plant metabolism. Euphorbia lathyris L. possesses non-articulated laticifers that produce triterpenoid-rich latex, but the mechanistic basis of laticifer specialization and latex metabolism remains unclear. Here, we generate the single-nucleus transcriptomic landscape of E. lathyris leaves and resolve a continuous laticifer trajectory with progressive activation of the mevalonate-derived triterpenoid pathway. Genes encoding the rubber biosynthetic complex, including cis - prenyltransferase ( CPT ), CPT-binding protein ( CBP ), and small rubber particle protein ( SRPP ), were specifically expressed in laticifers, indicating potential rubber formation. Ultrastructural and chemical analyses detect small rubber particles (∼150 nm) and a low-abundance cis -1,4-polyisoprene fraction in latex (0.30–0.47% w/w) with short average chain length ( Mw ≈ 150–180 kDa). The streamlined repertoire of rubber biosynthetic pathway genes and the absence of Hevea -like rubber elongation factors ( REFs ) may be associated with the observed low rubber content and smaller molecular weight in E. lathyris . Network inference and validation identified a laticifer-specific DOF transcription factor, COGWHEEL1 (ElCOG1), that binds the promoters of ElCPT1 and butyrospermol synthase 1 ( ElBUT1) and represses their activity , indicating a shared negative transcriptional control point acting on both the rubber-elongation and triterpenoid branches. In summary, this single-nucleus transcriptomic landscape of E. lathyris laticifers clarifies their metabolic specialization and establishes a framework for dissecting the regulatory programs of specialized secretory cells in latex-bearing plants. In Brief Single-nucleus RNA-seq resolves the differentiation trajectory of laticifers in Euphorbia lathyris , and particle morphology, ultrastructure, and size profiling define latex-associated rubber particles. Regulatory network analysis reveals coordinated activation of rubber and triterpenoid biosynthesis in laticifers and identifies ElCOG1 as a negative regulator of both pathways. • snRNA-seq resolves the differentiation trajectory of E. lathyris laticifers. • Morphology, ultrastructure and size profiling define rubber particles in E. lathyris . • NR-related genes are fewer and weaker expressed than in Hevea laticifers. • Rubber and triterpenoid biosynthesis are co-activated in laticifers. • ElCOG1 negatively regulates both rubber and triterpenoid synthesis.