Transcriptomic profiling and differential alternative splicing of citrus in response to infestation by Asian citrus psyllid, Diaphorina citri

The Asian citrus psyllid, Diaphorina citri Kuwayama, is the principal vector of huanglongbing pathogens and poses a severe threat to citrus production worldwide. Transcriptional and post-transcriptional regulation mediated by alternative splicing (AS) are well-established mechanisms underlying plant resistance to insect infestation. Thus, a comprehensive understanding of these processes in citrus following D. citri infestation is essential for developing effective host resistance strategies.

We investigated transcriptomic alterations and AS dynamics in citrus shoots at 24 h post-feeding (hpf24) and 48 h post-feeding (hpf48) following D. citri infestation. A total of 2,273 and 3,049 differentially expressed genes (DEGs) were identified at hpf24 and hpf48, respectively. Among these, 19 upregulated DEGs were associated with jasmonic acid (JA) biosynthesis and signaling pathways, indicating activation of JA-mediated defense responses. AS analysis revealed that feeding by D. citri significantly altered pre‑mRNA splicing. At hpf24, 422 differential alternative splicing (DAS) events corresponding to 363 genes were detected, and this number increased to 717 DAS events corresponding to 580 genes at hpf48, with intron retention being the predominant AS type. Integrative analysis of gene expression and AS profiles demonstrated a limited overlap between DEGs and differentially spliced genes. This suggests that AS may function, at least partially, independently of transcriptional regulation during citrus defense against D. citri infestation. Finally, nine JA-related genes were selected for validation of their relative expression levels by quantitative real-time PCR.

Our study elucidates the coordinated transcriptomic and spliceomic reprogramming underlying citrus defense responses to D. citri infestation, highlighting the activation of JA‑mediated defenses and widespread AS events that largely operate independently of transcriptional changes. These findings provide novel molecular insights into citrus-psyllid interactions, with potential implications for future resistance breeding strategies.