Detection and Molecular Variation of Jujube Witches' Broom Phytoplasma in Resistant Jujube Scions Grafted on Diseased Root Stocks in Three Jujube Orchards

[Objective] This study aimed to detect the jujube witches '-broom（JWB） phytoplasma status of jujubes cultivated in three jujube orchards after inoculating the trees by graft,and to analyze the transmission,epidemic,heritable variation,and phylogeny of different phytoplasma strains;and reveal the relationship between different phytoplasma strains and different resistance jujube cultivars.[Method] In April 2017,different resistant jujube scions were collected and grafted on the phytoplasma-infected rootstocks cultivated in three jujube orchards including Yuquanshan and Changping orchards in Beijing and Juncheng orchard in Tang county,Hebei province.The total DNA of scion and rootstock tissue samples were extracted from August to October of that year,to be used as templates for PCR amplification.Specific PCR products of 16 S rDNA,16 S-23 S intergenic region（SR）,secA,tuf,fusA-tuf intergenic region,himA and its downstream putative protein gene were sequenced.Genetic variation and phylogenetic evolution were analyz