Detection And Identification Of Four Phytoplasmas In Woody Plants In Shaanxi Province

We determined the taxonomy status of phytoplasmas associated with peach red leaf(PRL) disease and willow proliferation disease based on the results of histology andmolecular biology examinations. The taxonomy status of jujube witches’ broom phytoplasmawas defined by analyses with rp and secY genes of phytoplasmas. The secY and nusA genes ofphytoplasma were used for classifying the paulownia witches’ broom phytoplasma.Samples of peach leaves exhibiting red leaf symptom were collected in Yangling,Shaanxi Province. Typical phytoplasma-like bodies were observed under transmissionelectron microscope in the phloem cells within the petioles of symptomatic peach leaves.Phylogeny analysis and restricted fragment length polymorphism (RFLP) analysis with16SrRNA genes indicated that the PRL phytoplasma was a member of subgroup16SrI-C.Willow proliferation (WiP) disease was observed in Yulin, Shaanxi Province and Erdos,Inner Mongolia. Phylogenetic analysis and virtual RFLP analysis of phytoplasma16S rRNAgene sequences indicated that the WiP phytoplasma belonged to16SrVI-A subgroup. Thiswas the first record of occurrence of phytoplasmas of group16SrVI in China.Jujube witches’ broom (JWB) was an important disease in Shaanxi, Shanxi andShandong provinces, and JWB phytoplasmas has been classified into16SrV-B subgrouppreviously based on analyses with16S rRNA genes. To differentiate the JWB phytoplasmas inthe three regions, the rp (1196bp) and secY genes (1431bp) were yielded. The sequences ofrp genes as well as secY gene of JWB phytoplasmas were identical to one another. Phylogenyanalyses indicated that all the three strains of JWB phytoplasmas belonged to subgroup16SrV-B.Leaf samples were collected from paulownia trees exhibiting witches’ broom symptomin six areas of Xunyi, Binxian, Yongshou, Yangling, Zhouzhi and Baoji in Shaanxi Province.The secY genes (1358bp) as well as the nusA gene (946bp) of paulownia witches’ broom(PaWB) phytoplasmas were amplified by PCR respectively. The sequences of secY genes aswell as nusA genes of the six phytoplasma strains were identical with one another. Phylogenyanalyses indicated that the PaWB phytoplasma in Shaanxi belonged to subgroup16SrI-D...