Plant cell walls are composed of polysaccharides such as cellulose, hemicelluloses, and pectins, whose location and function differ depending on plant type. UDP-Ara mutases (UAMs) have been reported to play important roles in plant development and response to various plant stresses (abiotic and biotic). However, little work has been reported on UAM in wheat. In this study, we dissected the role of the UAM family member, UAM3, during the interaction between wheat and the stripe rust fungus, Puccinia striiformis f. sp. tritici (Pst), and in response to treatment with salicylic acid (SA). RNA interference (RNAi)-based stable silencing of TaUAM3 resulted in decreased resistance to Pst fungus. In addition, CRISPR-mediated genome editing (GE) of TaUAM3 enhanced the susceptibility of wheat to Pst or compromised disease resistance accompanied by increased fungal growth and decreased H2O2 production in plant tissues. Moreover, the transcript levels of pathogenesis-related (PR) genes and reactive oxygen species (ROS)-generating genes were down-regulated in both the RNAi-silenced and CRISPR-edited plants, while the ROS-scavenging gene, TaCAT3, was up-regulated. Therefore, TaUAM3 positively regulates the resistance of wheat to Pst.