The United Graduate School of Agricultural Science, Tottori University, Tottori 680-8553, Japan.
Faculty of Agriculture, Tottori University, Tottori 680-8553, Japan.
Plant Physiol. 2023 Nov 22;193(4):2677-2690. doi: 10.1093/plphys/kiad482.
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 lisianthus (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 biosynthesis of gentiopicroside (GPS) and swertiamarin (SWM), characteristic monoterpene glucosides in Gentianaceae, was upregulated in gibberellin-treated E. grandiflorum roots. Moreover, these metabolites considerably promoted hyphal branching in the Glomeraceae AM fungi Rhizophagus irregularis and Rhizophagus clarus. GPS treatment also enhanced R. irregularis colonization of the monocotyledonous crop chive (Allium schoenoprasum). Interestingly, these metabolites did not provoke the germination of the root parasitic plant common broomrape (Orobanche minor). Altogether, our study unveiled the role of GPS and SWM in activating the symbiotic relationship between AM fungi and E. grandiflorum.
植物源独脚金内酯触发丛枝菌根（AM）真菌的菌丝分枝，从而启动陆地植物与 AM 真菌之间的共生关系。然而，我们之前的研究表明，赤霉素处理的六出花（Eustoma grandiflorum，龙胆科）使用不同于独脚金内酯的未知分子激活 AM 真菌的根际菌丝分枝。在这项研究中，我们分析了 E. grandiflorum 的独立转录组数据，发现龙胆科特征性单萜葡萄糖苷，龙胆苦苷（GPS）和獐牙菜苦苷（SWM）的生物合成在赤霉素处理的 E. grandiflorum 根中上调。此外，这些代谢物显著促进了 Glomeraceae AM 真菌不规则根毛菌（Rhizophagus irregularis）和明显根毛菌（Rhizophagus clarus）的菌丝分枝。GPS 处理还增强了不规则根毛菌对单子叶作物细香葱（Allium schoenoprasum）的定殖。有趣的是，这些代谢物并没有引发根寄生植物普通列当（Orobanche minor）的萌发。总的来说，我们的研究揭示了 GPS 和 SWM 在激活 AM 真菌与 E. grandiflorum 共生关系中的作用。
