Novel Plant Growth Regulator Guvermectin Promotes Root Development by Modulating Auxin Signaling

Guvermectin (GV), a novel plant growth regulator from
rhizosphere
microorganism, has been officially registered as a new biopesticide
in China. It plays important roles in regulating plant root growth
and development, while the underlying mechanisms remain largely unknown.
In this study, we demonstrate that GV induces auxin accumulation in Arabidopsis root tips and regulates root architecture through
an auxin signaling-dependent pathway. Mechanistic investigation revealed
that GV activates the indole-3-pyruvic acid biosynthetic pathway of
auxin biosynthesis by upregulating the expression of YUC family genes, thereby increasing endogenous indole-3-acetic acid
levels in the root tip. Concurrently, GV modulates polar auxin transport
by downregulating PIN2 protein abundance, thereby reducing basipetal
auxin efflux and promoting localized auxin retention. Collectively,
these findings elucidate a dual regulatory mechanism whereby GV coordinates
auxin biosynthesis and transport to optimize root growth. Our work
bridges the gap between its agronomic application and molecular mechanism,
offering a theoretical foundation for its integration into precision
agriculture.