miR-278-3p targets ATG16L1 to modulate autophagy and suppresses CLas proliferation in Diaphorina citri

The phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas) is the primary cause of citrus Huanglongbing (HLB) and is transmitted by the Asian citrus psyllid, Diaphorina citri. MicroRNAs (miRNAs) are key posttranscriptional regulators involved in various biological processes, yet their role in D. citri's response to CLas infection remains unclear. In this study, we found that autophagy levels were significantly elevated in CLas-infected D. citri compared to non-infected individuals. Modulating autophagy influenced CLas titers, suggesting its role in pathogen suppression. Small RNA sequencing identified differentially expressed miRNAs, with miR-278-3p being significantly downregulated by 72.3%. Functional analyses revealed that miR-278-3p regulates autophagy by targeting ATG16L1. Inhibition of miR-278-3p increased autophagosome formation, whereas its overexpression suppressed autophagy. Dual-luciferase reporter assays confirmed miR-278-3p directly binds to the 3'UTR of ATG16L1, negatively regulating its expression. Notably, miR-278-3p inhibition reduced CLas titers by 48.7%, demonstrating its role in pathogen defense. These findings provide novel insights into the molecular mechanisms underlying insect-pathogen interactions and highlight the potential of miRNA-based strategies for controlling plant diseases transmitted by insect vectors. Understanding these regulatory pathways may lead to innovative pest and disease management approaches in agriculture.