The Iranian provinces where sugar beet is cultivated have been surveyed for the presence of soil-borne sugar beet viruses. Beet necrotic yellow vein virus (BNYVV) was detected in 288 of the 392 samples collected in Iran. A-type BNYVV was mostly detected. The p25 coding region on BNYVV RNA-3 was amplified by RT-PCR. Nine different p25 variants of the highly variable amino acid tetrad at positions 67 to 70 were identified i.e. ACHG, AHHG, AYHG, ALHG, AFHR, AFHG, AHYG, VLHG and VHHG. The first three variants were the most commonly found. In 23 out of the 303 BNYVVpositive samples we detected the P type of BNYVV. Surprisingly, none of these samples contained the fifth RNA species usually associated with P type BNYVV in other countries. The Beet black scorch virus was also detected in 62 of 203 samples in ten out of thirteen Iranian provinces. The BBSV satellite was found in 18 of 203 samples in nine provinces. The quasi absence of BBSV infection in the warmer provinces is possibly due to the fact that O. brassicae are less tolerant to warmer temperature than other Olpidium sp. The Beet soil-borne virus was detected in 101 of 203 samples in all of provinces under cultivation of sugar beet. By comparison of the nucleotide sequence of the coat protein gene, the Iranian BSBV were shown similar to other BSBV isolates from Germany, France and USA. The Beet virus Q was finally detected in 34 samples in five different Iranian provinces. The distribution and co-occurrence of these four viruses will be analyzed

Keywords