Molecular Identification Of Four Phytoplasmal Diseases In China

The phytoplasmas associated with air-plant phyllody,willow phyllody, common smoketree dieback and Chinese elm yellows were identified at molecular levels.The main results read as follows:The 16S rRNA gene,ribosomal protein gene(rp) and elongation factor Tu(EF-Tu) (tuf gene) of the phytoplasma associating with air-plant phyllody were amplified with normal or nested-PCR.Sequence analysis results show that the phytoplasma belongs to aster yellows group.The phytoplasma particles were observed under electron microscope.Graft experiment also conformed that air-plant phyllody is caused by phytoplasma.Phytoplasma of aster yellows group was also detected from willow plants showing symptom of phyllody.The associating phytoplasma belongs to 16Sr I-B according to 16S rRNA sequence and belongd to rp I-D according to rp gene sequence.Common smoketree dieback is caused by phytoplasma.Blast results of 16S rRNA sequences showed that the phytoplasma belongs to subgroup 16Sr I-B. Alignment results of this and other twelve 16S phytoplasmal rRNA that the corresponding phytoplasma belongs to subgroup 16Sr I-B.Psyllas inhabiting on common smoketree are probably the insect vector of common smoketree dieback disease.Phytoplasmal 16S rRNA fragment is also amplified and sequence from elm plants showing yellowing.The sequence analysis results showed that the phytoplasma associating with Chinese elm yellowing belongs to subgroup16Sr V-B of elm yellows group.