Construction of infectious clone of Mashhad isolate Beet black scorch virus and studying the reaction of some sugar beet cultivars to it under greenhouse conditions

Beet black scorch virus (BBSV) is a soil-borne virus infecting sugar beet. In order to construct an infectious full-length cDNA clone of Mashhad isolate (IR-Mash1), Iran (GenBank Accession no. MK092329), and studying reaction of some sugar beet cultivars, sugar beet roots with beard lateral root growth were collected from Mashhad field and subjected to total RNA extraction and then cDNA synthesis. PCR reaction was performed to amplify the whole genome of the virus were cloned to pDrive Cloning Vector. DNA was extracted from the plasmid vector. It was used as templates for run-off transcription in vitro by use of a T7 RNA polymerase. Chenopodium quinoa was inoculated under greenhouse conditions. Necrotic local lesions formed on C. quinoa (5 dpi) leaves were used as inoculation material for inoculation of the leaves of different sugar beet cultivars grown in the greenhouse. BBSV was inoculated by rubbing the sugar beet seedling leaves. Iranian cultivar including Sharif (susceptible check), Aria, Shokoufa and foreign cultivar including Pauletta KWS (tolerant to Rhizomania and sugarbeet cyst nematode), Isabella KWS (Double Resistant to Rhizomania) and Dorothea (tolerant to Rhizoctonia) cultivars were inoculated under greenhouse conditions. Pinpoint Symptoms appeared on the leaves of all cultivars after twenty days. The result showed that the virus produces similar symptoms on leaves of susceptible and resistant cultivars to Rhizomania. So, using infectious clone, possible to screening sugar beet germplasms as part of pre-breeding programs under greenhouse conditions and to find sources of resistance to the virus in sugar beet and wild beets.