Institute of Plant Biology

Arbuscular mycorrhizal (AM) symbiosis is the name given to the endosymbiotic association of a plant root and a fungus from the phylum Glomeromycota. More than 80% of vascular plants can be colonized by AM fungi. Inside root inner cortex cells, the fungal hyphae develops highly branched tree-like structures called arbuscule, which is the major site for nutrient exchange between fungi and plant. From my past research, I found that 70% of the overall Pi acquired by the rice cultivar Nipponbare is delivered via the symbiotic route. Surprisingly , mutations in PT11 or PT13, two symbiosis-specific rice Pi transporters, both affected fungal colonization and arbuscule formation, so each gene is essential for AM symbiosis. However, for symbiotic Pi uptake, only PT11 is necessary and sufficient. Besides, so far the transcriptional regulation mechanism of PT11 and PT13 is still mysterious and worth for further investigation. Like PT11 and PT13, a set of genes which was exclusively expressed in myc orrhizal roots might be essential for the cellular reprogramming during AM symbiosis. However, so far the transcriptional regulation mechanism of these genes was not fully understood. Transcription factors which expression is up-regulated by AM symbiosis are often important for AM symbiosis. By comparing the transcriptomes between non-mycorrhizal and mycorrhizal rice using RNA-Seq technology, AM-specific or induced transcription factors in rice can be identified. The expression of these candidate genes can be confirmed in tomato to see if the conservation exists between monocot and dicot. The function and target genes regulated by these transcription factors can be further analyzed. Even though the benefits of AM symbiosis on host plant stress tolerance are widely reported, the molecular mechanisms behind is still unclear. In order to find the possible plant-AM combination for improving plant stress tolerance, several combinations between the host plant, tomato and rice, and the AM fun gi, will be tested under drought and salt stress conditions. During this process, different stress responses resulted from diverse combination between plants and AM fungi will be acquired for further analysis to identify the molecular mechanisms. To identify which pathways might be essential for symbiosis- related stress tolerance, the transcriptome and metabolomics approach will be applied on plants with different treatments, including non-mycorrhizal and mycorrhizal plants grown with or without stress. These analyses could help us to find the candidate genes or metabolites highly correlated with symbiosis-involved stress tolerance.​