Stripe rust fungus subverts wheat phase separation-mediated immunity to promote infection.

Abstract

Liquid-liquid phase separation (LLPS) has emerged as an important strategy for plant stress resistance, yet its dynamic regulation during plant-pathogen interaction remains poorly understood. Here, we demonstrate that the stripe rust fungus <i>Puccinia striiformis</i> f. sp. <i>tritici</i> (<i>Pst</i>) deploys effector Hasp170 (one haustorial secreted protein) to subvert wheat immunity by directly disrupting host LLPS. Hasp170 targets the intrinsically disordered region (IDR1) of the wheat nuclear protein TaPSTE (phase separation protein targeted by effector), which forms LLPS-dependent biomolecular condensates. Within these condensates, TaPSTE recruits the transcription factor TaNF-YC, thereby activating the expression of genes driving reactive oxygen species burst and Ca²⁺ influx, key components for disease resistance. By binding TaPSTE's IDR1, Hasp170 impairs condensate formation and prevents TaNF-YC recruitment, consequently suppressing host immunity and facilitating fungal parasitism. This reveals a virulence strategy where pathogens directly manipulate host biomolecular condensates to evade immune responses.