Abstract
Recent studies of symbiotic mutants of Lotus japonicus have led to isolation of a number of host genes, which are required for endosymbioses with both rhizobia and arbuscular mycorrhiza. These genes are termed "common sym genes" and thought to be essential for early signaling processes required for successful infection of plant cells by symbiotic fungi and bacteria. The seven common sym genes identified so far are all conserved in rice that is known as a mycorrhizal plant. On the other hand, non-mycorrhizal plant Arabidopsis thaliana loses half of them. This suggests that common sym genes are universally involved in plant-arbuscular mycorrhiza symbiosis.
To confirm the involvement of common sym genes in rice-arbuscular mycorrhiza symbiosis, we isolated and characterized their rice orthologues, OsCASTOR, OsPOLLUX and OsCCaMK. Furthermore, OsPOLLUX and OsCCaMK deficient rice mutants, isolated from the Tos17 mutant library, show symbiotic defective phenotypes in arbuscular mycorrhizal infection.
