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

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

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.795695

DOI=10.3389/fpls.2021.795695

ISSN=1664-462X

ABSTRACT=<p>Morphotypes of arbuscular mycorrhizal (AM) symbiosis, <italic>Arum</italic>, <italic>Paris</italic>, and Intermediate types, are mainly determined by host plant lineages. It was reported that the phytohormone gibberellin (GA) inhibits the establishment of <italic>Arum</italic>-type AM symbiosis in legume plants. In contrast, we previously reported that GA promotes the establishment of <italic>Paris</italic>-type AM symbiosis in <italic>Eustoma grandiflorum</italic>, while suppressing <italic>Arum</italic>-type AM symbiosis in a legume model plant, <italic>Lotus japonicus</italic>. 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 <italic>L. japonicus</italic> (<italic>Arum</italic>-type), <italic>Daucus carota</italic> (Intermediate-type), and <italic>E. grandiflorum</italic> (<italic>Paris</italic>-type). Despite of the similarities, the fungal colonization levels and the expression of symbiosis-related genes were suppressed in <italic>L. japonicus</italic> and <italic>D. carota</italic> but were promoted in <italic>E. grandiflorum</italic> 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 <italic>L. japonicus</italic> and <italic>E. grandiflorum</italic>. Additionally, differential regulation of genes involved in sugar metabolism suggested that disaccharides metabolized in AM roots would be different between <italic>L. japonicus</italic> and <italic>D. carota</italic>/<italic>E. grandiflorum</italic>. 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.</p>