The Cyclophilin Effector TaCYPE1 From the Tomato Leaf Miner Tuta absoluta Suppresses Plant Immunity by Targeting Host RNA-Binding Proteins.

Abstract

The leaf-mining insect Tuta absoluta is a highly destructive pest that deploys candidate effector proteins to modulate host defences; however, the molecular mechanisms underlying this manipulation remain poorly understood. In this study, we characterise TaCYPE1, a predicted secreted cyclophilin-like effector, and demonstrate its role in promoting insect virulence. Transient expression of TaCYPE1 in Nicotiana benthamiana suppresses pattern-triggered immunity (PTI), including INF1-induced cell death, reactive oxygen species (ROS) burst, and defence-related gene expression. Notably, this immune suppression occurs independently of the conserved peptidyl-prolyl cis-trans isomerase (PPIase) activity of TaCYPE1. Stable overexpression of TaCYPE1 in tomato increases host susceptibility and enhances larval feeding, confirming its virulence function in a crop host. Mechanistically, TaCYPE1 physically interacts with host glycine-rich RNA-binding proteins (GR-RBPs), including SlRBP1 in tomato and NbRBGA in N. benthamiana, the latter contributes positively to selected immune responses and anti-herbivore defence. Domain-mapping analyses reveal that TaCYPE1 interacts with the conserved RNA-recognition motifs (RRMs) of GR-RBPs, and similar interactions are observed among GR-RBP homologues in solanaceous plants. Collectively, our findings identify TaCYPE1 as a virulence-associated factor that attenuates plant immunity through targeting GR-RBP-mediated regulatory processes, revealing a previously unrecognised layer of post-transcriptional modulation in plant-insect interactions.