Abstract
Arbuscular mycorhiza (AM) is mutualistic plant-microbe interaction observed in more than 80% of land plants. In this symbiosis, mycorrhizal fungi provide inorganic materials to the host plant and in return, obtain photosynthetic products from the host. In addition, legume plants acquired the other form of symbiosis, root nodule symbiosis (RNS) by sharing some signaling factors with AM. Recent studies about RNS system revealed the signaling factors and mechanisms, and the knowledge was applied to the AM system through the shared mechanisms. However the AM specific system has been poorly understood because there are few tools for the molecular analysis of AM. Therefore, we established an AM gene maker 'SbtM1', which was specifically induced during AM and worked in the colonization of AM fungi in the host root. The fluorescent protein fusion with SbtM1 promoter visualized infected cells of AM fungi. In addition, the fusion with the secretion signal peptide of SbtM1 enabled visualization of the AM fungi in the host root. Using the AM specific response of the gene maker, we isolated two AM-response cis regions in the promoter.
