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The genus Phytophthora consists of many species that are arguably the most destructive plant pathogens causing widespread damage to ornamental, agronomic, and forest ecosystems throughout the world.A variety of molecular techniques have been used for identification of Phytophthora species.The most accurate molecular method for identification of isolates to a genus-or species-level is accomplished by development of molecular markers and sequence analysis of specific loci.The introns of the SNARE-related gene YKT6 were sufficiently polymorphic for the development of molecular markers for almost all Phytophthora species, with more conserved flanking coding regions appropriate for the design of Phytophthora genus-specific primers.The Phytophthora genus-specific primer set P-YKT6-F/P-YKT6-R was able to amplify a single band about 600 bp in tested 24 different Phytophthora species, no amplified product from any of the Pythium spp.and other true fungi tested.PCR with the P.sojae specific primer set Ps-YKT6-F/Ps-YKT6-R or P.capcisi primer set Pc-YKT6-F/Pc-YKT6-R amplified a specific 399 bp or 282 bp band only from isolates of P.sojae or P.capcisi separately.For P.sojae or P.capcisi, the detection sensitivity was achieved to 100 pg and 10 fg in standard PCR and nested PCR, respectively.These primers also proved to be efficient in detecting pathogens from diseased plant tissues, residues and soils.In addition,real-time quantitative PCR assays coupled with the species-specific primers were developed to detect and quantify the pathogen.The results demonstrated that the YKT6-based molecular marker and methods have great potential as a tool for identification and detection of Phytophthora spp.in a range of applications from pathogen surveys to statutory testing.