Genetic diversity of and selection pressure on grapevine fanleaf virus movement protein in Iranian isolates

Movement protein (MP) plays multiple roles in plant pathogenic viruses, especially in cell-to-cell movement for establishing systemic infection. The grapevine fanleaf virus-MP is responsible for cell-to-cell movement of GFLV by introducing tubular structures through the plasmodesmata in host plants. In the present study, genetic diversity of GFLV-MP gene was investigated in Iranian isolates of the virus collected from Markazi, East-Azarbaijan, West-Azarbaijan, Zanjan, Ardabil, and Qazvine provinces. Selection pressure on this gene was furthermore estimated. A total of 245 leaf samples were collected randomly, of which 33 reacted positively in GFLV specific DAS-ELISA Kit. The GFLV-MP gene was amplified by RT-PCR and subsequently was cloned and sequenced. Phylogenetic analysis based on the MP gene uncovered that there were at least two lineages of the GFLV isolates in Iran. Moreover, sequence data analysis showed that the MP gene had constant size of 1044 nucleotides in the all GFLV isolates meaning that this gene did not tolerate any insertion or deletion events. Estimated population genetic parameters revealed that the MP gene of GFLV in Iranian and other isolates of GFLV was under sever purifying (negative) selection pressure, but it was not distributed on the MP gene uniformly.