Molecular Detection And Identification Of Six Phytoplasmal Diseases In Shandong Province

Phytoplasmal disease is a worldwide disease. So far,there are 1000 phytoplasmal diseases have been found worldwide and only 100 phytoplasmal diseases have been .reported in China. In this study, we identified six phytoplasmal disease in Shandong province using molecular biotechnoligy, the main results are as follows:The symptoms of rose (Rosa rugosa cv. plena) witches'-broom(RoWB) included stunting, yellowing, witches'-broom and dieback. The disease was graft-transmissible. Phytoplasma cells were observed in diseased phloem under electron microscopy. Sequence alignment of 16S rRNA, tuf and rp genes confirmed that the phytoplasma associated with RoWB belonged to 16SrI-D subgroup of Candidatus Phytoplasma asteris (16SrI group),which was also the causal agent of Paulownia witches'-broom and might be transmitted from the paulownia tree that is several meters away. The phytoplasma associated with rose witches'-broom is different from the one reported in foreign counties.A specific fragment of ca. 1.2 kb in length was amplified with nested PCR from spiraea plants showing typical phytoplasma symptom of yellowing, witches'-broom and dieback. The fragment was sequenced and subjected to RFLP and phylogenetic analysis. RFLP analysis showed that the phytoplasma associated with spiraea witches'-broom belonged to 16Sr I-B subgroup of Aster yellows phytoplasma group. This phytoplasma shared the highest homology of 99.6% with Severe aster yellows (SAY) in subgroup 16Sr I-B.Elm plants exhibiting typical phytoplasma disease symptoms of witches'-broom were observed in Zhaoyuan and Tai'an City, Shandong Province. RFLP and phylogenetic analysis showed that the phytoplasma associated with elm witches'-broom in these two cities belonged to Ca. Phytoplasma asteris.Fragments of ca. 1.2 kb in length were amplified by nested-polymerase chain reaction from samples showing symptoms of cherry phyllody, Chinese scholartree and pomegranate fasciated. RFLP and phylogenetic analysis showed that the phytoplasmas associated with these three diseases all belonged to Ca. Phytoplasma asteris (16SrI group). Cherry phyllody phytoplasma may be a new subgroup of 16SrI group. This is the first report of cherry phyllody and pomegranate fasciated diseases in the world. Rose witches'-broom, spiraea witches'-broom, and elm witches'-broom disease were new records in China. Chinese scholartree fascinated was once reported in China. In this study, we reported the molecular characterization of the phytoplasma associated with Chinese scholartree fascinated.