An effector from cotton bollworm oral secretion impairs host plant defense signaling

Significance Plants recognize insect-derived molecules and make the accurate defense response during herbivory. However, insects release effectors that disturb host plant defense responses for fitness. Effectors are crucial components in biotic interactions. We identified a caterpillar-derived effector (HARP1) from oral secretion of cotton bollworm, a devastating agricultural pest. HARP1 is released from larvae to plant leaves during feeding and is able to migrate from wounding site into plant cells automatically. HARP1 interacts with JASMONATE-ZIM-domain (JAZ) proteins, the suppressor of Jasmonate (JA) pathway, and blocks signaling transduction by preventing JAZ degradation. HARP1-like proteins are widely distributed and have conserved function in noctuids, and they may contribute to insect adaptation to host plants during coevolution.