Conservation and Diversity in Gibberellin-Mediated Transcriptional Responses Among Host Plants Forming Distinct Arbuscular Mycorrhizal Morphotypes

Takaya Tominaga; Chihiro Miura; Yuuka Sumigawa; Yukine Hirose; Katsushi Yamaguchi; Shuji Shigenobu; Akira Mine; Hironori Kaminaka

doi:10.3389/fpls.2021.795695

Conservation and Diversity in Gibberellin-Mediated Transcriptional Responses Among Host Plants Forming Distinct Arbuscular Mycorrhizal Morphotypes

Front Plant Sci. 2021 Dec 16:12:795695. doi: 10.3389/fpls.2021.795695. eCollection 2021.

Authors

Takaya Tominaga¹, Chihiro Miura², Yuuka Sumigawa², Yukine Hirose², Katsushi Yamaguchi³, Shuji Shigenobu³, Akira Mine^{4

5}, Hironori Kaminaka²

Affiliations

¹ The United Graduate School of Agricultural Sciences, Tottori University, Tottori, Japan.
² Faculty of Agriculture, Tottori University, Tottori, Japan.
³ Functional Genomics Facility, NIBB Core Research Facilities, National Institute for Basic Biology, Okazaki, Japan.
⁴ Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
⁵ JST, PRESTO, Kawaguchi, Japan.

Abstract

Morphotypes of arbuscular mycorrhizal (AM) symbiosis, Arum, Paris, and Intermediate types, are mainly determined by host plant lineages. It was reported that the phytohormone gibberellin (GA) inhibits the establishment of Arum-type AM symbiosis in legume plants. In contrast, we previously reported that GA promotes the establishment of Paris-type AM symbiosis in Eustoma grandiflorum, while suppressing Arum-type AM symbiosis in a legume model plant, Lotus japonicus. This raises a hitherto unexplored possibility that GA-mediated transcriptional reprogramming during AM symbiosis is different among plant lineages as the AM morphotypes are distinct. Here, our comparative transcriptomics revealed that several symbiosis-related genes were commonly upregulated upon AM fungal colonization in L. japonicus (Arum-type), Daucus carota (Intermediate-type), and E. grandiflorum (Paris-type). Despite of the similarities, the fungal colonization levels and the expression of symbiosis-related genes were suppressed in L. japonicus and D. carota but were promoted in E. grandiflorum in the presence of GA. Moreover, exogenous GA inhibited the expression of genes involved in biosynthetic process of the pre-symbiotic signal component, strigolactone, which resulted in the reduction of its endogenous accumulation in L. japonicus and E. grandiflorum. Additionally, differential regulation of genes involved in sugar metabolism suggested that disaccharides metabolized in AM roots would be different between L. japonicus and D. carota/E. grandiflorum. Therefore, this study uncovered the conserved transcriptional responses during mycorrhization regardless of the distinct AM morphotype. Meanwhile, we also found diverse responses to GA among phylogenetically distant AM host plants.

Keywords: Daucus carota; Eustoma grandiflorum; Lotus japonicus; Rhizophagus irregularis; arbuscular mycorrhizal morphotypes; arbuscular mycorrhizal symbiosis; comparative transcriptomics; gibberellin.