Monoterpene glucosides accumulated inEustoma grandiflorumroots promote hyphal branching in arbuscular mycorrhizal fungi

Abstract

AbstractHost plant-derived strigolactones trigger hyphal branching in arbuscular mycorrhizal (AM) fungi, initiating a symbiotic interaction between land plants and AM fungi. However, our previous studies revealed that gibberellin-treatedEustoma grandiflorum(Gentianaceae) activates rhizospheric hyphal branching in AM fungi using unidentified molecules other than strigolactones. In this study, we analyzed independent transcriptomic data ofE. grandiflorumand found that the gentiopicroside (GPS) and swertiamarin (SWM), which are characteristic monoterpene glucosides in Gentianaceae, were highly biosynthesized in gibberellin-treatedE. grandiflorumroots. Moreover, these metabolites considerably promoted hyphal branching in the Glomeraceae AM fungiRhizophagus irregularisandR. clarus. GPS treatment also enhancedR. irregulariscolonization of the monocotyledonous cropAllium schoenoprasum. Interestingly, these metabolites did not provoke the germination of the root parasitic plantOrobanche minor. Altogether, our study unveiled the crucial role of GPS and SWM in activating the symbiotic relationship between AM fungi andE. grandiflorum.