El-kereamy, A. and Jayasankar, S. 2013. Cloning and differential expression of a plum single repeat-MYB, PdMYB3, in compatible and incompatible interactions during fungal infection. Can. J. Plant Sci. 93: 599-605. Enhancing resistance to pathogen attack through conventional breeding is a major challenge, especially in perennial species. Monilinia fructicola fungal infection causes brown rot disease, resulting in economic damage of stone fruits at flowering, pre- and post-harvest stages. The molecular mechanism of resistance to this disease is still not known. In the present study, we cloned and analyzed the expression of a novel MYB transcription factor from European plums (PdMYB3) induced in response to M. fructicola fungal infection. The identified PdMYB3 is a single repeat-MYB protein that contains a conserved SHAQKYF motif. Monilinia fructicola infection induces the expression of PdMYB3 in fruits of four cultivars within 24 h; however, it is differentially expressed in the susceptible and resistant varieties. By comparing four different cultivars we found that PdMYB3 is induced in much higher levels in the susceptible cultivars than the resistant ones. In addition the PdMYB3 expression is higher in the early stages of fruit development prior to pit hardening, suggesting a potential role for PdMYB3 during this stage. Promoter analysis revealed the presence of some hormone cis-elements suggesting a possible role for PdMYB3 gene in transmitting a signal from the hormonal pathways to downstream components during host-pathogen interactions.