Transcriptome and Hormone Profiling of NPR1-Mediated Responses to Candidatus Liberibacter asiaticus

In this project, we investigated the earliest plant responses to HLB infection by comparing gene expression and hormone dynamics in susceptible citrus plants and NPR1-overexpressing tolerant plants. Using RNA sequencing and hormone profiling shortly after infection, we found that NPR1-overexpressing plants are primed for defense even before pathogen exposure and respond more precisely once infection begins. These plants showed improved regulation of phloem defenses, reduced harmful oxidative stress, and balanced hormone signaling compared to susceptible plants.Together, our findings demonstrate that NPR1 enhances HLB tolerance by coordinating early immune signaling with controlled structural, oxidative, and hormonal responses. This work provides new mechanistic insight into plant tolerance to HLB and identifies molecular pathways that could be targeted to develop more resilient citrus varieties.