Molecular detection and identification of sweet cherry virescence phytoplasma
To confirm phytoplasma infection,samples of sweet cherry(Prunus avium L.)plants showing virescence symptom were collected from an orchard in Tai'an.Total DNAs were extracted from symptomatic and asymptomatic plants for PCR amplification.A 16SrDNA fragment of 1 248 bp in length were amplified from diseased cherry tissue,but not from healthy plant,using universal prim-ers for phytoplasmal 16SrRNA gene.The similarity coefficient between the SCHV and the 16SrV-B subgroup of jujube witches'-broom phytoplasma(AB052876)is 1.00.Phylogenetic analysis based on rp genes revealed that SCHV belonged to rpV-C subgroup.Sequence analysis indicated the tuf gene of SCHV was clustered with jujube witches'-broom phytoplasma JWB-XFDO(GU968759),belonging to the 16SrV group.In conclusion,this study clarified the classification of sweet cherry virescence phytoplasma isolated from Tai'an,providing a foundation for local disease detection,diagnosis,and scientific control.