Functional Characterization of CaSpr2 in Jasmonate-Dependent Induced Defense Against Western Flower Thrips in Capsicum annuum

Insect infestation poses a significant threat to global agriculture by impairing plant growth and reducing crop yields. The western flower thrip (WFT) causes substantial damage through both direct feeding and transmission of plant viruses. Although the jasmonic acid (JA) signaling pathway is known to participate in plant defense against WFTs, the underlying molecular mechanisms in non-model crops such as peppers, remain largely elusive. This study investigates the role of suppressor of prosystemin-mediated responses2 (Spr2) within JA-mediated defense against WFTs in pepper. Through an integrated approach employing virus-induced gene silencing (VIGS), transcription analysis, phytohormone quantification, insect behavior assays and life history investigations, we demonstrated that silencing CaSpr2 significantly reduced JA and JA-Ile accumulation, and led to a strong feeding preference of WFTs for CaSpr2-silenced plants. Furthermore, the adult lifespan, survival rate, female fecundity, oviposition rate, and population parameters of WFTs were significantly improved on CaSpr2-silenced plants. Spr2 functions as an essential component within the JA signaling pathway, thereby playing a critical role in conferring resistance to WFTs in cultivated pepper. These findings provide profound insights and practical implications for breeding thrips-resistant cultivars in non-model plants, through genetic manipulation of JA signaling, offering a promising avenue for sustainable agricultural pest management.