http://dx.doi.org/10.1016/j.cub.2016.06.072

Abstract

Hemibiotrophic pathogens are some of the mostdestructive plant pathogens, causing huge economiclosses and threatening global food security. Infectionwith these organisms often involves an initial biotrophicinfection phase, during which the pathogenspreads in host tissue asymptomatically, followed bya necrotrophic phase, during which host-cell death isinduced. How hemibiotrophic pathogens trigger hostnecrosis and how plants inhibit the transition fromthe biotrophic stage to the necrotrophic stage in diseasesymptom expression are mainly unknown. Therice blast fungus Magnaportheoryzae spreads in ricebiotrophically early during infection, but this biotrophicstage is followed by a pronounced switch tocell death and lesion formation. Here, we show thatthe M. oryzaeeffector AvrPiz-t interacts with thebZIP-type transcription factor APIP5 in the cytoplasmand suppresses itstranscriptional activity and proteinaccumulation at the necrotrophic stage. Silencing ofAPIP5 in transgenic rice leads to cell death, andthe phenotype is enhanced by the expression ofAvrPiz-t.Conversely, Piz-t interacts withandstabilizesAPIP5 to prevent necrosis at the necrotrophic stage.At the same time, APIP5 is essential for Piz-t stability.These results demonstrate a novel mechanism forthe suppression of effector-triggered necrosis at thenecrotrophic stage by an NLR receptor in plants.