Analysis of salivary proteins in gall-inducing psylla and their potential influence on host plants

Gall-forming insects manipulate host plants through the proteins present in their saliva, which play essential roles in reprogramming plant cells. In this study, we utilized an integrated transcriptomic and proteomic approach to explore the salivary proteome of camphor psylla (Trioza camphorae). Transcriptomic analysis identified 97 secretory proteins that were abundantly and specifically expressed in the salivary glands. Proteomic analysis further revealed 69 secretory proteins in the salivary glands and 21 proteins in the secreted saliva. Collectively, 168 proteins were identified as potential salivary components of T. camphorae. Comparative analysis of T. camphorae saliva with other herbivorous insects unveiled 66 conserved salivary proteins. Interestingly, in contrast to the closely related Diaphorina citri, which lacks gall formation ability, 68 T. camphorae salivary proteins exhibited species-specificity. Due to the challenges of overexpressing proteins in camphor trees, we used Nicotiana benthamiana as a heterologous system to preliminarily assess salivary protein function. Three proteins were found to alter N. benthamiana physiology, though their specific roles in T. camphorae-camphor tree interactions require further investigation. Our findings contribute to a deeper understanding of the molecular mechanisms underlying insect-induced gall formation, and might be useful in the future management of forest pests.