The effects of gibberellin on the expression of symbiosis-related genes in <i>Paris</i>-type arbuscular mycorrhizal symbiosis in <i>Eustoma grandiflorum</i>

Arbuscular mycorrhiza (AM) is a symbiotic interaction in terrestrial plants that is colonized by fungi in the Glomeromycotina. The morphological types of AM, including the <i>Arum</i>-type and <i>Paris</i>-type, are distinct, depending on the host plant species. A part of the regulatory pathways in <i>Arum</i>-type AM symbiosis has been revealed because most model plants form the <i>Arum</i>-type AM with a model AM fungus, <i>Rhizophagus irregularis</i>. Moreover, gibberellin (GA) is known to severely inhibit AM fungal colonization in <i>Arum</i>-type AM symbiosis. Recently, we showed that exogenous GA treatment significantly promoted AM fungal colonization in <i>Paris</i>-type AM symbiosis in <i>Eustoma grandiflorum</i>. In this study, we focused on the transcriptional changes in AM symbiosis-related genes in GA-treated <i>E. grandiflorum</i>. The expression levels of all examined <i>E. grandiflorum</i> genes were maintained or increased by GA treatment compared with those of the control treatment. Our new results suggest that signaling pathway(s) required for establishing AM symbiosis in <i>E. grandiflorum</i> may be distinct from the well-characterized pathway for that in model plants.