丁香卷叶病植原体的分子鉴定

 通过透射电子显微镜，在表现卷叶、褪绿症状的丁香(Syringa oblata)样品的叶脉韧皮部筛管细胞内观察到大量植原体粒子。应用植原体16S rRNA基因通用引物对P1/P7和R16F2n/R16R2对表症丁香植株总DNA进行巢式PCR扩增，得到了约1.2 kb的目标片段，通过对扩增片段进行测序、系统发育分析和同源性分析，结果表明，该片段长度为1 246 bp，在系统发育进化树上与翠菊黄化组（Candidatus Phytoplasma asteris）成员是聚集在一起的，与该组成员同源性均在98%以上。用16Sr RNAⅠ组和Ⅴ组特异引物确定了该病害非混合侵染所致，相似性系数和RFLP分析表明该植原体属于16SrⅠ B亚组。这是国内关于翠菊黄化组植原体在丁香上感染的首次报道。

Molecular detection and identification of a phytoplasma associated with lilac leaf roll

In those of Syringa oblata plants showing symptoms of leaf roll,chlorotic,a great quantity of structures resembling phytoplasmas were observed in small pieces of phloem sieve elements by Electron microscopy.Nested PCR using a combination of phytoplasma-specific universal primer pairs(P1/P7-R16F2n/R16R2) amplified 16S rDNA with the expected size(1.2 kb) from all samples of symptomatic S.oblata plants.On the basis of sequencing,phylogenetic analysis and nucleotide alignments to PCR products,a 1 246 bp fragment was obtained that clustered together with the members of ’Candidatus Phytoplasma asteris’ and shared a 98% similarity.Group specific primer pairs R16(Ⅰ)F1/R16(Ⅰ)R1 and R16(Ⅴ)F1/R16(Ⅴ) proved that this disease was caused by unmixed infection.Similarity coefficient and RFLP analysis indicated that it was belonged to phytoplasmas members of 16Sr I-B.This is the first time to report group ’Candidatus Phytoplasma asteris’ infecting S.oblata plants in China.