Detection and sequencing of apple dimple fruit viroid in apple trees.
The apple branches, leaves and phloem collected from an old orchard in Yanji, Xinjiang were used as materials for total RNA isolation using the method designed. Specific fragments of apple dimple fruit viroid (ADFVd) were amplified by RT-PCR using the primers designed according to the sequence X99489 on GenBank. 7 sequences were obtained through recovering and sequencing; 5 sequences had high homology over 98%, the other two sequences only about 85%, also registered in GenBank (acc. No. EU031497_EU031503). The cDNA probe labelled by digoxigenin was prepared from plasmids containing target DNA of ADFVd and it can be successfully used for ADFVd detection. At the same time, the detection results by in situ RT-PCR proved the presence of ADFVd in apple leaf, and it mainly located in nucleus of mesophyll cell.