First Report of Beet soil-borne virus on Sugar Beet in Iran.

Abstract

Sugar beet is a main field crop in Iran and is cultivated in 186,000 ha. During the summer of 2001, sugar beet (Beta vulgaris) plants with pale, often upright, narrow, and rolled leaves were collected from the six main beet cultivation provinces of Iran (Fars, Ghazvin, Kermanshah, Khorasan, Semnan, and Isfahan). Roots of symptomatic plants were small, often with constriction, and exhibited warty outgrowth, proliferation of fibrous roots, and vascular necrosis. Beet soil-borne virus (BSBV) and Beet necrotic yellow vein (BNYVV, genus Benyvirus) were detected in sugar beet root samples by tissue-blot immunoassay (TBIA) using BSBV- and BNYVV-specific monoclonal antibodies (As-0576.1 and As-0799.1/CG6-F4, respectively; DSMZ Plant Virus Collection, Germany). Root extracts of sugar beet plants infected with BSBV, were infective by mechanical inoculation to Chenopodium quinoa causing necrotic ring spots. BSBV was detected in inoculated plants by TBIA. Laboratory tests using TBIA on 2,387 randomly collected samples showed that BSBV was present in 406 plants (17%) and BNYVV was present in 1,347 plants (56.43%). BSBV resembles BNYVV, the causal agent of sugar beet rhizomania, morphologically and in its transmission by Polymyxa betae (1). BNYVV has been reported previously from Iran (2). To our knowledge, this is the first report of BSBV occurring on sugar beet in Iran.