小麦蓝矮病植原体延伸因子(EF-Tu) tuf基因序列的同源性分析

 【目的】利用分子生物学方法分析小麦蓝矮病植原体延伸因子tuf基因，从亚组水平上确定小麦蓝矮病植原体的分类地位。【方法】电镜观察自然发病的小麦蓝矮病病叶；用引物fTufu/rTufu对小麦蓝矮病植原体延伸因子tuf基因进行PCR扩增；核苷酸序列测定及分析。【结果】经电镜超微结构观察，在韧皮部观察到大量典型植原体。通过PCR扩增得到约850 bp的特异片段。感受态转化后，进行测序，结果表明小麦蓝矮病植原体tuf基因片段长842 bp，编码280个氨基酸。分析比较15种植原体延伸因子tuf基因的同源性，结果表明小麦蓝矮病植原体与三叶草绿变（KVF）亲缘关系最近，核苷酸同源性为99.9％，氨基酸同源性为100％。【结论】从亚组水平上确定了小麦蓝矮病植原体的分类地位，为研究小麦蓝矮病植原体的来源及致病分子机理提供理论依据。

Homologic Analysis of tuf Gene for Elongation Factor Tu of Phytoplasma from Wheat Blue Dwarf

【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.