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The citrus industry has been threatened by Huanglongbing (HLB) for over a century. Here, an HLB-induced Arabidopsis <i>RPM1-interacting protein 4</i> (<i>RIN4</i>) homologous gene was cloned from <i>Citrus clementina</i>, and its characteristics and function were analyzed to determine its role during citrus–<i>Candidatus</i> Liberibacter asiaticus (<i>C</i>Las) interactions. Quantitative real-time PCR showed that <i>RIN4</i> was expressed in roots, stems, leaves and flowers, with the greatest expression level in leaves. Its expression was suppressed by gibberellic acid, indole-3-acetic acid, salicylic acid and jasmonic acid treatments, but was induced by abscisic acid and salt treatments, as well as wounding. The transient expression of a RIN4-GFP showed that RIN4 was localized in the cell membrane. <i>RIN4</i>-overexpressing transgenic <i>C. maxima</i> cv. ‘Shatianyou’ plants were obtained, and some transgenic plants showed greater sensitivity to <i>C</i>Las infection and earlier HLB symptoms appearance than non-transgenic controls. Results obtained in this study indicated that the upregulated expression of <i>RIN4</i> in HLB diseased citrus may aid <i>C</i>Las infection.