To effectively monitor the occurrence of major sweet potato viruses,the multiplex RT-PCR assay was established for detection of Sweet potato feathery mottle virus( SPFMV),Sweet potato latent virus( SPLV)and Sweet potato virus 2( SPV2). Three pairs of specific primers were designed based on the conserved region sequences of the coat protein( CP) gene published in GenBank. The mainly factors including the concentration of primer and polymerase,reaction cycles and annealing temperature were optimized. Three sp...