Comparative analysis on Arum- and Paris-type arbuscular mycorrhizal symbioses in tomato roots

Most terrestrial plants associate with arbuscular mycorrhizal (AM) fungi to gain mineral nutrients from the partners. In the interaction, AM fungal morphologies in the host roots are known to change depending on the host species: Arum- and Paris-type AMs. Since recent studies often focus on legume plants forming Arum-type AM, we have compared the regulatory mechanisms of Arum- and Paris-type AM symbioses in several host plants. However, using phylogenetically distant plants, comparative analysis possibly detects the genetic differences among plants. Therefore, this study conducted comparative transcriptomics on Arum- and Paris-type AM symbioses in Solanum lycopersicum (tomato) that forms both types of AMs depending on AM fungal species. As a result, AM-related genes exhibited similar transcriptional responses during Arum- and Paris-type AM symbioses. In contrast, gibberellin biosynthetic pathway and defense response were transcriptionally promoted during Paris-type AM symbiosis in tomato roots. Our results suggest that fundamental regulation of AM symbiosis was shared irrespectively to AM morphotypes; however, some different transcriptional reprogramming would associate with establishing Arum- and Paris-type AM symbioses in tomato roots.