The goal is to understand how citrus interacts with�Candidatus Liberibacter asiaticus (Las) infection. To achieve the goal of this research, we are conducting the following objectives:�Objective 1. Identification of the receptors for Las PAMPs in susceptible and tolerant citrus varieties21 outer membrane proteins have been cloned and the putative targets in citrus are being identified using Yeast 2 hybrid system.�Potential PAMPs from Las (either homologous to known PAMPs or pilin genes) LasFlaA (flagellin), LasEF-Tu, LasCSP (cold shock protein), LasSSBP (single strand binding proein) and pilin assembly genes (named LasPil85, LasPil95, LasPil105 and LasPil115)� were cloned under 35S promoter and the Arabidopsis phloem specific promoter�SUC2 and introduced into Agrobacterium. We will be testing their receptors in Tobacco and citrus.�Objective 2. Generate transgenic/cisgenic citrus expressing PAMP receptors recognizing LasWe are cloning and overexpressing the selected PAMP receptors.Objective 3. Investigate the roles of effectors in HLB disease developmentFor the 10 selected SDEs, we have conducting Y2H and identified their targets in Valencia sweet orange. We are in the process of confirming the targets using other approaches such BiFC and co-IP assays. We will conduct Y2H and SPR assays to identify their targets in Poncirus.���