Geographic distribution and molecular characterization of Turkish isolates of the citrus chlorotic dwarf-associated virus

Abstract

Citrus chlorotic dwarf-associated virus (CCDaV) was first reported in Turkey’s Eastern Mediterranean Region (EMR) in the late 1980s. No studies have been conducted on its presence in the other important citrus cultivation regions of Turkey until this publication. To investigate the potential spread of CCDaV we conducted surveys in commercial orchards, residential and hotel gardens, and recreational areas in four different citrus cultivation regions outside of the EMR. Plants were examined visually and a total of 141 samples showing symptoms similar to CCDaV were collected. Only one out of 141 samples tested positive for CCDaV. This sample was collected from garden grounds of a hotel in Antalya and, to the best of our knowledge, is the first report of CCDaV infection outside of the EMR in Turkey. CCDaV infection was not detected in any of the surveyed commercial citrus orchards. To determine the molecular characteristics and population structures of the CCDaV isolates, additional surveys were performed to obtain CCDaV isolates from different citrus species in EMR. Following sample collection and virus identification work, complete genome sequences were determined for CCDaV isolates from five different citrus species and a citrus hybrid cultivated commercially in Turkey. Analysis of these genomes showed sequence identities over 96% between themselves and with the Chinese CCDaV isolates. Phylogenetic studies showed that Turkish and Chinese samples clustered into different groups, based on their complete genomes and gene regions.