Abstract: 【Objective】The aim is to analyze the phytoplasma tuf gene of wheat blue dwarf (WBD). Then this study can differentiate and classify phytoplasma of WBD from subgroup.【Method】 Diseased wheat was observed under the electron microscope and primers (fTufu/rTufu) for phytoplasma tuf gene(EF-Tu) were used to amplify DNA samples extracted from infected wheats, then the amplified fragment was transformed into the plasmid, sequenced and analysed. 【Result】Phytoplasmas were observed in the phloem sieve elements of leaf tissues from naturally-infected wheat under the electron microscope. A 850 bp DNA fragement was amplified in DNA samples from infected wheats but not in those extracted from healthy plants. The sequencing result revealed that the tuf gene of phytoplasma from wheat blue dwarf was 842 bp in length, which encoding 280 amino acids. Homology analysis for sequences of tuf gene from 15 kinds of phytoplasmas showed that the tuf gene of WBD was closely related to those of clover phyllody (KVF), homology rate of nucleotide sequences and amino acids was 99.9% and 100%, respectively.【Conclusion】Homology analysis for sequences of tuf gene can differentiate and classify phytoplasma of wheat bule dwarf from subgroup, thus providing a theoretical basis for research of the phytoplasma origin and molecular nosogenesis of wheat bule dwarf.

Key words: Wheat blue dwarf (WBD), Phytoplasma, tuf gene for elongation factor Tu, Homology