| Low molecular weight RNAs were extracted from40apple samples and18pear samples,which were collected from223Farming&Herding Regiment in Hejing County, XinjiangUygur Autonomous Region. Then the samples were detected by Return-PAGE and RT-PCR.The results showed that Y1,Y6, Y8, Y10of ’Golden delicious’ of the40apple samples wereinfected with Apple scar skin viroid (ASSVd); Z3, Z7of the early pears of the18pearsamples were infected with Apple scar skin viroid (ASSVd); the infection of the place was10.3%. Apple dimple fruit viroid (ADFVd) and Apple fruit crinkle viroid (AFCVd) weredetected from all samples for testing, the results showed that all samples were not detected.Some positive samples of apple and pear were purified and then amplified by reversetranscription-polymerase chain reaction (RT-PCR). The results showed that the ASSVdisolates had over85%nucleotide sequence identity with previously published sequences inGenBank. Sequence variation of ASSVd isolates from apple and pear in Xinjiang was small,especially the central conserved region, and the sequence homology between the differentgeographical and different hosts was high, and the results illustrated that the sequencevariation of ASSVd was no significant correlation with its geographical and hosts.Corresponding to the measured leaves, peel and seed of the positive samples were detectedby RT-PCR, the results showed that all of them were infected by ASSVd. The range of theplants infected with ASSVd was wide, including the phloems, leaves and fruits.In this study,6ASSVd isolates composed of4ASSVd sequences from apple (Goldendelicious)(accession no. KC110858~KC110861) and2ASSVd sequences from pear(Precocious pear)(accession no. JX861258~JX861259) were deposited into GenBank.We have in-depth studied the RT-PCR system for ASSVd, establish and optimize theRT-PCR system for Apple scar skin viroid, ASSVd distribution of plants were studied by insitu RT-PCR, the results showed that the RNA positive signals of Apple scar skin viroid aremainly located in the nucleus of the leaf mesophyll tissue of apple (Golden delicious) andpear (Precocious pear). |
