小麦蓝矮病植原体16S rDNA基因片段的比较分析

 小麦蓝矮病是陕西乃至西北冬麦麦区的一个重要病害,由介体条沙叶蝉专化性传播。对小麦蓝矮病株叶片和带毒条沙叶蝉进行超薄切片及电镜观察,在叶片韧皮部和叶蝉后肠中均观察到大量典型植原体。利用植原体16S rDNA基因保守序列通用引物对Rm16F2/Rm16R1,应用PCR技术从小麦蓝矮病株叶片中扩增到1.4 kb的特异片段。通过对16S rDNA基因片段序列同源性比较,结果表明小麦蓝矮病病原与三叶草绿变、翠菊黄化、绣球花绿变、草莓矮化和番茄巨芽植原体亲缘关系较近,其同源率为99.2%~99.9%。据此可以判定小麦蓝矮病植原体是属于植原体16SrⅠ组,确定了其分类地位。

Comparition and analysis of 16S rDNA fragment of phytoplasma of wheat blue dwarf

Wheat blue dwarf(WBD) is an important disease of winter wheat disseminated by Psammotettix striatus L.in Shaanxi and Northwest area.Phytoplasma was observed in the phloem sieve elements of wheat leaf tissues and hind intestine of P.striatus L.under the electron microscope.Using primers(Rm16F2/Rm16R1) for phytoplasma 16S rDNA,a 1.4 kb DNA fragment was amplified by polymerase chain reaction in DNA samples extracted from infected wheats but not in those extracted from healthy plants.Homology analysis of nucleotide sequences showed that the amplified 16S rDNA fragment from WBD was closely related to those of clover phyllody(CPh),aster yellows(AY),hydrangea phyllody(HP),blueberry stunt(BBS) and tomato big bud(TBB),with homology rate 99.2%-99.9%.Our results suggest thatWBD is caused by a phytoplasma in 16SrⅠgroup.