Heat shock proteins (HSPs) serve as molecular chaperones for diverse client proteins in many biological processes. In plant immunity, cytosolic HSP90s participate in immune receptor complex assembly, stability control and/or activation. In this study, we report that in addition to the well-established positive roles HSP90 isoforms play in plant immunity, they are also involved in the negative regulation of immune receptor accumulations. Point mutations in two HSP90 genes, HSP90.2 and HSP90.3, were identified from a forward genetic screen designed to isolate mutants with enhanced disease resistance. We found that specific mutations in HSP90.2 and HSP90.3 lead to heightened accumulation of immune receptors including SNC1, RPS2 and RPS4. HSP90s may assist SGT1 in the formation of SCF E3 ubiquitin ligase complexes that target immune receptors for degradation. Such regulation is critical for maintaining appropriate immune receptor protein levels to avoid autoimmunity.This article is protected by copyright. All rights reserved.