Malectin-like domain-containing receptor-like kinases (MRLKs) compose a big and diverse protein family in plants that playssignifi cant roles in biotic and abiotic stress response. However, the MRLK family members in Citrus, as well as their rolesduring drought stress (abiotic stress) and arbuscular mycorrhizal fungi (AMF) colonization, remain relatively unknown. Inthe present study, we characterized the MRLK family genes in Citrus. By analyzing the presence of malectin-like domainsand searching through the Citrus genome, we identifi ed 47 CsMRLKs located within nine chromosomes, with most CsMRLKsmainly located on chromosome 1. These 47 CsMRLK family members were classifi ed into 6 subfamilies with distinct malectindomains. Gene expression analysis showed that all 47 CsMRLKs were expressed in the roots and exhibited diff erentialexpression patterns. During the drought stress response, CsMRLK6 , 7 , 8 , 9 , 10 , 11 , 19 , 25 , 26 , and 40 were downregulated. AMF colonization downregulated the expression of CsMRLK6 , 10 , 11 , 12 , 14 , 17 , 20 , 30 , 35 , 43 , and 47 and upregulatedthe expression of CsMRLK2 , 5 , 13 , 21 , 22 , 28 , 29 , 32, 38 , 41 , 45 , and 46 . In addition, AMF colonization and drought stressshowed a synergistic eff ect, in which the downregulated genes became even more weakened and the upregulated genesbecame even more enhanced. The present study off ers useful perception into the Citrus MRLK gene family and its responsesin AMF colonization and drought stress.