Thesis (Ph.D.) - Cairo University - Faculty Of Agriculture - Department Of Plant Pathology and Physiology

A new Ilravirus infecting sugar beet plants was isolated for the first time in EgyptThe virus was given the provisional name beet necrotic ringspot virus BNRSV - EGBNRSV - EG caused ring spot , line pattern and calico mosaic on sugar beet in the fieldIt infected several hosts belonging to seven familiesBNRSV - EG was transmitted mechanically and through Thrips tabaci insects , but not through Myzus persicae aphids or through the tested seeds of some sugar beet cultivarsNine commercial cvs were found to be susceptible to BNRSV - EGccording to indirect ELISA testVirus infection increased the ? - amino nitrogen , moisture , sodium , potassium content and sugar loss in molasses in all tested sugar beet roots infected with BNRSV - EG compared with healthy root plantsOn the other hand , virus infection decreased the sugar purity , polarization , sugar extractability , sugar extract and protein content of infected sugar beet roots compared with healthy rootsThe incidence of sugar beet infection with BNRSV - EG in this study rated 4125and 34 in the tested field in Kafr El - Sheikh and El - Fayoum , respectivelyPurified BNRSV - EG migrated in sucrose gradient forming three components with average A260 / 280 of 15 and 163 for un - fractionated and fractionated components , respectivelyCoat protein subunits of BNRSV - EG had a value of 29 KDaGenomic RNAs were separated into four species of RNAs in agarose gel electrophoresisSeveral serologic tests indicated its close ties with the Ilarvirus , Prunus necrotic ringspot virus , PNRSVMolecular studies showed the ability of the universal Jc 10 / Jc 12 primer pairs for PNRSV to amplify 641 bp of the coat protein gene of both PNRSV and BNRSV - EG further , BNRSV - EG coat protein gene had a Mse 1 restriction site similar to the sever isolates of PNRSVNucleotide sequence analysis of the 641pb amplified - coat protein gene of BNRSV - EG indicated 6580 similarities with the published sequences of IlarvirusesSequence relationship between BNRSV - EG isolate and PNRSV CH3 , CH19 , ring 21 and ring 28 isolates was 9315 , 9103 , 9047 and 8914

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