Abstract
Herbivore-associated molecular patterns (HAMPs) enable plants to recognize herbivores and may help plants adjust their defense responses. Here, we report on herbivore-induced changes in a protein disulfide isomerase (PDI) widely distributed across arthropods. PDI from the spider mite Tetranychus evansi (TePDI), a mesophyll-feeding agricultural pest worldwide, triggered immunity in multiple Solanaceae plants. TePDI-mediated cell death in Nicotiana benthamiana required the plant signaling proteins SGT1 (suppressor of the G2 allele of skp1) and HSP90 (heat shock protein 90), but was suppressed by spider mite effectors Te28 and Te84. Moreover, PDIs from phylogenetically distinct herbivorous and nonherbivorous arthropods triggered plant immunity. Finally, although PDI-induced plant defenses impaired the performance of spider mites on plants, RNAi experiments revealed that PDI genes are essential for the survival of mites and whiteflies. Our findings indicate that plants recognize evolutionarily conserved HAMPs to activate plant defense and resist pest damage, pointing to opportunities for broad-spectrum pest management.