We report the characterization and genetic variations of a novel betanucleorhabdovirus infecting sugar beet in Iran. Pairwise comparison of the obtained betanucleorhabdovirus sequence with betanucleorhabdoviruses from GenBank showed that it shares the highest nucleotide identity with tomato betanucleorhabdovirus 2 (TBRV2) and Sambucus betanucleorhabdovirus 4. The obtained sequence contained six open reading frames (ORFs) in antigenomic sense flanked by complementary 3′ leader and 5′ trailer sequences (3\\\'-N-P-P3-M-G-L-5\\\'). In the phylogenetic tree, the detected isolate was clustered with the betanucleorhabdoviruses and was most closely related to TBRV2, tomato betanucleorhabdovirus 1, and Sambucus betanucleorhabdovirus 1 to 5. The genome organization, phylogenetic relationships, and sequence similarities to other betanucleorhabdoviruses suggest that the virus is a new member of the genus Betanucleorhabdovirus, which we propose to name beet betanucleorhabdovirus 1 (BNRV1). The virus’s partial spread and host-range investigations revealed that sugar beet fields in northeast Iran were infected by BNRV1, which also infects Chenopodium album, Malva neglecta, and Carthamus oxyacanthus weeds. Low values of Ks*, Kst*, Z*, and Snn indicate no substantial genetic differentiation between populations of this virus. Selection pressures on a portion of the BNRV1 N gene analyzed were negative, showing purifying selection was occurring. The magnitude of negative selection in the BNRV1 N gene was consistent with what has been reported for other betanucleorhabdoviruses.

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