Citrus psorosis virus, Causal Agent of Ring Pattern Disorder in Thomson Navel Trees in East of Mazandaran

Citrus psorosis virus (CPV) is causal agent of one of the important citrus diseases in the world. A disorder was observed on Thomson Navel orange trees on sour orange or citrange rootstocks, with ring spot symptoms on mature fruits, especially around the stylar end. It had often caused expanded yellow ring lesions on mature leaves. Severe fruit abscission was occurred in the infected trees. Leaf samples were collected from spring flashes of the infected trees and tested by TAS-ELISA, using Citrus psorosis virus (CPV) 13C5 monoclonal antibody and CPV infections were confirmed. RT-PCR was done with four pair primers closely related to ICRSV, CRSV-4, CPV-RNA2 and CPVCPG on leaves of thirty infected Thomson Navel orange trees. The samples only amplified by CRSV-4 primers and produced a fragment about 218bp. This fragment length size was similar to the fragment obtained from CPV ring spot isolates from Florida and Argentina. Seven isolates were selected for biological indexing and based on the indicator plants divided into two groups. Based on the serological, molecular and biological results, the isolates can be settled into Citrus psorosis virus, B type group, without bark scaling symptoms.