Egusa, M. | bioRxiv Science

bioRxiv2023

Monoterpene glucosides accumulated in Eustoma grandiflorum roots promote hyphal branching in arbuscular mycorrhizal fungi

Host 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-treated Eustoma grandiflorum (Gentianaceae) activates rhizospheric hyphal branching in AM fungi using unidentified molecules other than strigolactones. In this study, we analyzed independent transcriptomic data of E. grandiflorum and found that the gentiopicroside (GPS) and swertiamarin (SWM), which are characteristic monoterpene glucosides in Gentianaceae, were highly biosynthesized in gibberellin-treated E. grandiflorum roots. Moreover, these metabolites considerably promoted hyphal branching in the Glomeraceae AM fungi Rhizophagus irregularis and R. clarus. GPS treatment also enhanced R. irregularis colonization of the monocotyledonous crop Allium schoenoprasum. Interestingly, these metabolites did not provoke the germination of the root parasitic plant Orobanche minor. Altogether, our study unveiled the crucial role of GPS and SWM in activating the symbiotic relationship between AM fungi and E. grandiflorum.

plant biology↗

bioRxiv2021

Chitin-induced systemic disease resistance in rice requires both OsCERK1 and OsCEBiP and is mediated via perturbation of cell-wall biogenesis in leaves

O_LIChitin is a well-known elicitor of disease resistance whose recognition by plants is crucial to perceive fungal infections. Chitin can induce both a local immune response and a systemic disease resistance when provided as a supplement in soils. Unlike local immune responses, how chitin-induced systemic disease resistance is deployed has not been studied in detail. C_LIO_LIIn this study, we evaluated systemic disease resistance against the fungal pathogen Bipolaris oryzae by performing a transcriptome analysis and monitoring cell-wall composition in rice plants grown in chitin-supplemented soils. We also examined the local immune response to chitin by measuring the production of reactive oxygen species in leaves. C_LIO_LIChitins induced both local immune response and systemic disease resistance with differing requirements for the receptors OsCERK1 and OsCEBiP. Transcriptome analysis suggested that a perturbation in cell-wall biogenesis is involved in the induction of systemic disease resistance, an idea which was supported by the induction of disease resistance by treatment with a cellulose biosynthesis inhibitor and alterations of cell-wall composition. C_LIO_LIThese findings suggest that chitin-induced systemic disease resistance in rice is caused by a perturbation of cell-wall biogenesis in leaves through long-distance signalling after recognition of chitins by OsCERK1 and OsCEBiP. C_LI

plant biology↗