Molecular Identification And Sequence Analysis of the <i>Apple Scar Skin Viroid</i> (ASSVd) Isolated from Four Kinds of Fruit Trees in Xinjiang Province, China

Abstract

In this paper, low molecular weight RNAs were extracted from tender leaves and shoots of apple, pear, peach and apricot trees, which were collected from Yanqi, Hejing, Bohu, Heshuo, Xinhe, Korla and Aksu in Xinjiang province, China. Then the samples were detected by reverse transcription-polymerase chain reaction (RT-PCR) and in situ RT-PCR technology. The detection results demonstrated that four kinds of fruit trees were infected by Apple scar skin viroid (ASSVd) and the detection rates were 2.1%, 2.1%, 2.8% and 3.3% on apple, pear, peach and apricot trees, respectively. I n situ RT-PCR result further confirmed that the existence of ASSVd was mainly distributed in the nucleus of the leaf tissues. And then the RT-PCR products from the samples were cloned and sequenced, and we obtained 42 ASSVd nucleic acid sequences, which were registered in GenBank and the accession numbers was from EU031455 to EU031496 by using biological software to analyze and the total detection rate was 3.0%. The homology analysis results showed that the 42 isolated ASSVd sequences had 85%~100% nucleotide sequence identity with previously published sequence NC_001340 (Puchta et al.,1990). All this results indicated that the variation of nucleic acid sequence of ASSVd isolate in each host was not obvious and was no significant difference in regions and varieties. In this present study, we established the optimized detection methods of RT-PCR and in situ RT-PCR, which would lay a good foundation for the rapid identification of ASSVd in this four kinds of fruit trees.