To invade and colonize their hosts, fungal pathogens utilize a serious of effector proteins to suppress plant immunity.Many of these effectors are secreted, cysteine-rich proteins that may have a role in virulence.In the genome of Fusarium graminearum, the causal agent of the wheat and barley head blight disease, we identified 53 genes that encode secreted proteins and have no homologous sequences in GenBank or other sequenced fungal genomes.Deletion mutants of all these SUP (secreted unique protein) genes were generated and assayed for defects in growth, conidiation, sexual reproduction, DON production, and pathogenicity.Four of them, Sup1-Sup4, were found to be important for plant infection.Whereas Sup1 and Sup3 are required for infection of both wheat heads and corn stalks, Sup2 and Sup4 are only involved in wheat infection.In transient expression assays with the PVX-based system, all of them could block Bax-induced programmed cell death induced in Nicotianabenthamiana and wheat.The expression of Sup2 and Sup4 was significantly up-regulated during early infection stages up to 72h.Western blot analysis with GFP-fusion proteins confirmed that Sup2 and Sup4 were secreted proteins.Live-cell imaging suggested that Sup4-fusion proteins were expressed and secreted by invasive hyphae formed in wheat leaf sheath cells.Further characterization of the translocation and localization of the Sup-GFP fusion constructs was in progress.Additional experiments to determine whether Sup1-Sup4 function as important effector genes during wheat infection also are under the way.