PubMed · 2026-04-23
Scientists discovered that a sugar called mannose — released by an enzyme borrowed from four o'clock flowers — triggers a hormone signaling chain in plants that drives root branching and elongation. The mechanism runs through a genetic switch (MYB41) that activates brassinosteroid hormone production, revealing a previously unknown sugar-to-hormone relay governing root architecture.
Mannose released by the MirMAN enzyme significantly promoted both lateral root emergence and root elongation in thale cress, while raising endogenous auxin levels and upregulating at least six auxin-response and lateral-root development genes.
The transcription factor MYB41 was strongly induced by mannose and directly bound the promoter of DWF4 — a brassinosteroid biosynthesis gene — positively regulating its transcription and downstream hormone production.
Mutant plants lacking MYB41 had fewer lateral roots, reduced DWF4 expression, and measurably lower brassinosteroid content, establishing MYB41 as the critical molecular bridge between sugar signaling and hormone-driven root architecture.
