Identification of Wild Hosts of Watermelon Chlorotic Stunt Virus in South and Southeastern Iran

Watermelon chlorotic stunt virus (WmCSV) is one of the destructive viruses of watermelon in south and southeastern Iran. In order to identify the wild hosts of the virus, watermelon growing areas of Minab (Hormozgan province), Roodbar-e-Jonob and Arzuiyeh (Kerman province) were surveyed and weed samples collected within and around the severely infected farms. The infection of the samples was tested by PCR using specific primer pair. Results showed that 14 weed species from 12 genera and nine plant families are infected with WmCSV. Most of the infected weeds were symptomless and did not show any specific symptoms. All the infected weed species in this study are reported for the first time as the WmCSV host in the world. In order to compare WmCSV isolates from weed species, the amplified 655 bp segment of coat protein (CP) gene from 11 infected weeds were cloned and sequenced. Comparison of nucleotide and amino acid sequences of 11 WmCSV isolates showed close similarities with each other and with the GenBank isolates. The closest GenBank isolate was the previously reported Iranian isolate from Bandar-Abbas (Hormozgan province) with 98/9-99/2 and 96/8-100% homologies for nucleotide and amino acid sequences, respectively. According to the results of this study, weed species are secondary hosts and serve as the reservoirs of the WmCSV. Thus, these weeds could be potentially important in epidemiology of the virus.