P-429 - Transcriptional variation of Lotus japonicus and Brachypodium distachyon in response to four dikaryon strains of arbuscular mycorrhiza fungi

Arbuscular mycorrhizal fungi (AMF) are important soil fungi that form symbiosis with plant roots, helping them absorb nutrients and promoting growth. Strains of the same species are genetically diverse, including unique dikaryotic strains that contain two different types of nuclei in their aseptate hyphae. However, how plants respond to these genetically distinct AMF strains at the gene expression level remains unclear. In this study, we examined how two plant species a dicot legume (Lotus japonicus) and a monocot grass (Brachypodium distachyon) respond to four dikaryotic strains (A4, A5, G1, SL1) of the fungus Rhizophagus irregularis. By using RNA sequencing and modeling, we found that root colonization and plant gene expression varied depending on the specific plant-fungal genotype combination. The two plant species showed diverse transcriptional responses to the four strains, while mRNAs  of some core AM genes, such as well-established marker genes consistently accumulated to higher levels in response to all four strains. These findings highlight that AM symbiosis is not a uniform interaction but is influenced by the genetic makeup of both the plant and the fungus. Understanding this diversity of interactions could help improve AMF-based applications in agriculture and ecosystem management.