■ Introduction to Research〓 Research Area : Plant-Insect Interactions

Understanding of metabolic defense against
herbivores in plants〓 Prof.
GALIS Ivan

Plants activate powerful protective shield against feeding herbivores that involves biosynthesis of various toxic phytoalexins.
While spectrum of phytoalexins in plants is vast, their biosynthesis and regulation during herbivory are less known. We use
monocot plant models, including rice and sorghum, to identify
novel metabolic patterns associated with herbivory. We look fortranscriptional regulators involved in the regulation of biosynthetic genes for these compounds, in particular those induced
in response to herbivore attack. We also study the role of plant
hormones as secondary messengers in defense signaling pathways against herbivores.

Research on perception of herbivory in plants
The strength of plant defense largely depends on early detection of elicitor moleculesfrom herbivores which are deposited in plantwounds during feeding. As the number ofidentified elicitors is still limited, we aim identification of novel elicitors using rice plants
and their herbivores as our model systems.
We develop efficient bioassays for rapid detection and isolation of novel compounds, usebiochemical techniques for their characterization, and intact plants for functional analysesof these novel herbivory-associated molecular patterns (HAMPs).

〓 Assoc. Prof.
SHINYA Tomonori〓 Research Area : Plant-Pathogen Interactions

Involvement of phytocytokines in rice immunity
Plants cleverly regulate their immunity by secreting endogenous peptides called plant cytokines (phytocytokines). We
believe that understanding and optimizing phytocytokine signaling and theirnetworks will improve plant immunity, and we are conducting this research.
Recently, we have established a multi-omics pipeline to isolate potential
phytocytokines in rice and identified 236 endogenous secreted peptides thatwere induced during the disease resistance response (Plant Biotech J 2020).
These included cytokine-like peptides such as the cysteine-rich RALF7, thepost-translationally modified PSK4, and a novel family of IRPs that do notcontain any known domains. Further analysis revealed that IRPs do indeed
have cytokine activity and act as positive regulators of resistance to blast fungus, the most important pathogen of rice (bioRxiv 2021).

Effector-triggered immunity through small GTPaseOsRac1〓 Prof.
KAWANO Yoji

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Resistance (R) proteins are crucial intracellular receptors that detect attacks by insects and invasion by various pathogens,including fungi, bacteria and viruses. However, the signaling molecules which mediate R protein-induced immune responses
are not yet fully understood. We have previously shown that an intracellular switch, the small GTPase OsRac1, is a master
regulator controlling immunity in rice (Plant Cell 2016, Curr Genomic 2016, FPS 2014, COPB 2013, Rice 2010). However,
the mechanism by which OsRac1 receives signals from the immune receptors and becomes activated has remained unclear.
Thus, we explored OsRac1-binding proteins and identified the R protein Pit, which is an immune receptor for rice blast fungus, a prominent microbial disease of rice. Through various analyses, wedemonstrated that OsRac1 functions as a molecular switch, controlling ROS
production and hypersensitive cell death (CHM 2010) and a GDP/GTP exchanger OsSPK1 mediates the activation of OsRac1 by Pit1 (PNAS 2018).
Besides, we have found that anchoring Pit to the plasma membrane throughpalmitoylation, a type of lipid modification, is required for Pit-induced activation of OsRac1 on the plasma membrane (JBC 2014). Our work has therefore revealed the signaling pathway of the R protein Pit through OsRac1.