〓 Research Area : Plant-Pathogen Interactions

Design new rice plants to cope with pathogens
Earth's population is expected to reach 9 billion by 2050. Plant agriculture must change fundamentally to support this number of people by mid-century. Rice is the most important food cropand therefore, improvement of rice is a key research goal.
Our ultimate goal is to design new rice plants to cope with biotic and abiotic stresses and improve
important agronomic traits. We have been working on immune receptors and the small GTPaseOsRac1, which are major components of rice immunity. A comprehensive understanding ofimmune receptors and OsRac1 functions would allow the design of rice immune system to control
pathogens. We are also interested in how plants orchestrate epigenetic regulations in responding
to abiotic stresses. To address these issue, we have been investigating rice as a model systemwith a combination of several cutting-edge technologies including live imaging and gene editing.

Ongoing projects in Plant Immune Design Group[1] Clarify PAMP-triggered immunity in rice〓 Prof.
KAWANO Yoji

[2] Decipher effector-triggered immunity in rice

Pattern recognition receptors (PRRs) and Resistance (R) proteins are crucial receptors that detect attack by insects and invasion by various pathogens including fungi, bacteria, viruses, etc.
However, the signaling molecules which mediate PRR and R protein-induced immune responses
are not yet fully understood. We would like to address this important question and have revealed
that small GTPase OsRac1 acts as one of the master regulators in both PAMP-triggered immunity and effector-triggered immunity in rice.

〓 Research Area : Plant-Environmental Microbiology

Lanthanide-dependent enzyme and motility
in plant-associating methylotrophic bacteria
Plant emit large quantities of methanol through stomata as aresult of their growth and pectin degradation. Methanol canbe a good nutrient for bacteria and methanol-utilizing (methylotrophic) bacteria predominate on the aerial plant surface(phyllosphere). We focus on their methanol metabolism andsymbiosis with plants.
Methylobacterium species are commonly found in phyllosphere, and they can promote plant growth. They have methanol dehydrogenase (MDH) to oxidize methanol. Not only calcium-dependent MDH encoded by mxaF, recently it was foundthat lanthanide-dependent MDH is also encoded by xoxF in
the genomes of Methylobacterium species. This is the first enzyme described to date, to contain lanthanide. We investigate
the mechanism of expression switching between these MDHs,depending on the availability of lanthanide.
We also study molecular mechanism of the motility and chemotaxis in methylotrophs, which is important for the bacteria
to find and colonize plants. The chemotaxis is also affected bythe carbon source and lanthanide.

〓 Assoc. Prof.
TANI Akio

We have found new methylotrophic bacteria belonging tonovel genera. They have been isolated from rice rhizosphereusing lanthanide as an essential cofactor. They are named as
Oharaeibacter diazotrophicus SM30 and Novimethylophilus
kurashikiensis La2-4. Thus, lanthanide can be used for isolation of bacteria that contain xoxF, which can be found in manyso-believed non-methylotrophic bacteria and novel bacteria.

Methylobacterium aquaticum strain 22A

Strain 22A adhering plant root hair

Strain 22A chemotaxis toward methanol

Novimethylophilus kurashikiensis La2-4

Graduate School of Environmental and Life Science, Okayama University51