Molecular Variability Of Apple Scar Skin Viriod In East Of Shandong Province

Apple scar skin disease was one of the main diseases of apple fruit, It seriouslyaffected the commercial value and economic value of the fruit. The pathogen was Applescar skin viroid (ASSVd), the evolution of ASSVd was faster than its host. Because itsmolecular weight was low, and its reproducion relyed on enzyme system of host cellwhich required shorter time. Molecular variability could provide the theoretical basis forthe research of virus classification, diagnosis, epidemic and prevention.In this work we studyed ASSVd of Gala, Red General, Fuji in Muping, Penglai,Qixia, Zhaoyuan, Wendeng, then compared ASSVd nucleotide sequence in the same areaof different specieses and the same species in different areas. The results showed that：1、In this work56ASSVd variants were obtained.(1)46ASSVd variants with FM208142.1from India in the highest similarity,78.5%～100%. Among them,30variants of331bp were similar or identical withFM208142.1; among five330bp variants, FM330-2had8differences sites withFM208142.1, other4variants were similar with FM208142.1, variation sites in C regionand T1region; two332bp variants existed4,8different sites with FM208142.1respectively, variation sites also in C region and T1region. Phylogenetic tree showed:variants of330bp,331bp,332bp existed close genetic relationship with FM208142.1. Andsecondary structure prediction results showed rod-like structure. Although9variants weresimilar with FM208142.1, but the length of nucleotide sequence existed large differences,including four272bp variants, two371bp variants, one371bp variant, one342bp variant.Phylogenetic tree showed: besides342bp variant, other8variants existed close geneticrelationship with FM208142.1. Secondary structure prediction results showed: secondarystructure all existed branch, which different from most member of Pospiviroidae, and342bp variant existed more branch.(2) Among10special variants, one263bp variant with HG764206from India in thehighest similarity,77.20%; two333bp variants with KC110858.1from Xinjiang in thehighest similarity,95.2%; two365bp variants with FJ974062.1from Greece in the highestsimilarity,88.21%. one354bp, one355bp, one358bp and two359bp variants with GQ249347.1from Greece in the highest similarity,89.08%～91.64%. Phylogenetic treeshowed: total10special variants existed close genetic relationship with FM208142.1.Secondary structure prediction results showed：besides333bp variant, others secondarystructure existed branch,365bp variant existed more branch.2、Multiple sequence alignment of330～333bp in this work with NC001340,19information sites were obtained, mutation sites and information sites in P region、C regionand T1region of secondary structure.3、Gala, Red General, Fuji in the same area existed certain host specificity; Gala, RedGeneral in different areas existed certain regional specialization, but Fuji no obviouslyregional specialization.