Transcriptomic analysis on Rhizophagus irregularis treated with gentiopicroside

Our previous studies have shown that gibberellin (GA) significantly upregulates the infection of arbuscular mycorrhizal (AM) fungi in Eustoma grandiflorum (Gentianaceae) roots. However, the production of strigolactones, representative molecules activating AM fungal branching, is considerably inhibited symbiosis GA-treated E. grandiflorum roots. These findings indicate that E. grandiflorum would attract arbuscular mycorrhizal fungi using unidentified molecules. Therefore, we conducted transcriptomic analyses on GA-treated E. grandiflorum mycorrhizal roots and found that a Gentianaceae-specific monoterpene glucoside, gentiopicroside (GPS), was the possible stimulant. Indeed, GPS significantly increased hyphal branches in the model AM fungus Rhizophagus irregularis. Here, we investigated transcriptional responses of R. irregularis to GPS to reveal the mechanisms underlying GPS-mediated hyphal branching.