identification and molecular analysis of beet yellows virus (byv) in khorasan razavi province

beet yellows virus belong to the genus closterovirus in the closteroviridae family which is one the most important viruses of sugar beet worldwide. in order to identify and characterize some molecular aspects of the byv, 48 symptomatic leaf samples of sugar beet were collected from sugar beet field in khorasan razavi province of iran. leaves showing general yellowing, vein clearing and thickness were collected. in order to detect the byv in symptomatic samples rt-pcr reactions were done. coat protein of several byv symptomatic samples was amplified by rt-pcr. an amplification of the expected size of 615 bp for byv coat protein was obtained in these samples and then one of them sequenced. this sequence data was aligned with other reported byv using the blast and then analyzed with the aid of the dnaman version 7 software. it showed that this sequence covered the cp coding region of byv, and shared the highest nucleotide (94.79%) and amino acid (90.59%) identity with an ukrainian isolate (x73476). phylogenetic analyses were conducted with the clustal w method and visualized with mega (vers. 5.2). the results of phylogenetic analysis were consistent with the sequence comparison results.