Tell me more: roles of NPRs in plant immunity

• Plant immune systems and the role of NPR1 in systemic acquired resistance.
• Interplay of NPR1 with other SAR signalling components.
• Proteasome-mediated degradation of NPR1 in plant immunity.
• NPR1, NPR3, and NPR4 as SA receptors.
• Future directions in the study of NPR1 and its paralogues and orthologues in plant immunity.

Plants and animals maintain evolutionarily conserved innate immune systems that give rise to durable resistances. Systemic acquired resistance (SAR) confers plant-wide immunity towards a broad spectrum of pathogens. Numerous studies have revealed that NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR) is a key regulator of SAR. Here, we review the mechanisms of NPR1 action in concert with its paralogues NPR3 and NPR4 and other SAR players. We provide insights into the mechanisms of salicylic acid (SA) perception. We discuss the binding of NPR3 and NPR4 with SA that modulates NPR1 coactivator capacity, leading to diverse immune outputs. Finally, we highlight the function of NPR1 as a bona fide SA receptor and propose a possible model of SA perception in planta.