Beet virus Q (BVQ) is a soilborne pomovirus (family Virgaviridae) associated with rhizomania syndrome in sugar beet. In the present study, BVQ was investigated in sugar beet farms of 12 provinces in Iran by RT-PCR. Thirty-five out of 214 root samples resulted in a positive reaction to BVQ (16.3%). Moreover, 501-bp- long fragments of the coat protein gene of 11 Iranian isolates were purified, cloned, and sequenced. Phylogenetic analysis using the 501 bp fragment of 17 BVQ isolates (11 from this study and six retrieved from GenBank) showed that all isolates clustered in two main groups. Iranian isolates belonged to group I alongside isolates from France (AJ810289) and Germany (AJ223597). Iranian isolates shared 98.80–100% nucleotide sequence identity (98.19–100% amino acid identity) and 97.21–99.60% nucleotide sequence identity (96.99–99.40% amino acid identity) with the corresponding sequence of six other BVQ isolates available in the GenBank. Iranian isolates displayed the highest nucleotide and amino acid sequence identities of 98.80-99.60% and 98.19-99.40%, respectively, with the French isolate FP71 (AJ810289). To our knowledge, this is the first molecular characterization of BVQ in Iran. This information can be used in plant breeding to obtain virus-resistant plants.

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