# Phytoalexin sakuranetin attenuates endocytosis and enhances resistance to rice blast

## TL;DR

Rice produces sakuranetin, a compound that reduces fungal protein uptake and boosts resistance to rice blast disease.

## Contribution

Sakuranetin's novel role in attenuating endocytosis of fungal effectors to confer rice blast resistance is revealed.

## Key findings

- Rice lines with resistance genes have high sakuranetin levels and reduced endocytic trafficking of PM proteins.
- Sakuranetin attenuates clathrin-mediated endocytosis of fungal effector PWL2 and AvrCO39.
- Reduced endocytosis via sakuranetin is sufficient to confer resistance against rice blast.

## Abstract

Phytoalexin sakuranetin functions in resistance against rice blast. However, the mechanisms underlying the effects of sakuranetin remains elusive. Here, we report that rice lines expressing resistance (R) genes were found to contain high levels of sakuranetin, which correlates with attenuated endocytic trafficking of plasma membrane (PM) proteins. Exogenous and endogenous sakuranetin attenuates the endocytosis of various PM proteins and the fungal effector PWL2. Moreover, accumulation of the avirulence protein AvrCO39, resulting from uptake into rice cells by Magnaporthe oryzae, was reduced following treatment with sakuranetin. Pharmacological manipulation of clathrin-mediated endocytic (CME) suggests that this pathway is targeted by sakuranetin. Indeed, attenuation of CME by sakuranetin is sufficient to convey resistance against rice blast. Our data reveals a mechanism of rice against M. oryzae by increasing sakuranetin levels and repressing the CME of pathogen effectors, which is distinct from the action of many R genes that mainly function by modulating transcription.

Sakuranetin is an important phytoalexin. The authors find that sakuranetin in rice attenuates endocytosis of effectors from the fungus Magnaporthe oryzae and enhances resistance against rice blast.