Date Received: 30-09-2020 / Date Accepted: 05-01-2021
ThisstudywasconductedtodeterminethetransmissionmannersofSriLankancassavamosaicvirus(SLCMV)causing cassavamosaicdisease(CMD).Thepupaofwhitefly (Bemisia tabaci) was collectedfromthefieldand and lettodeveloptoadultsonthedisease-freecassava plantsin the pots.Thedisease-freeadultwhiteflieswereisolatedinacagefortwo months toobtain anon-viruliferouscolonyofwhitefliesfor the inoculation experiment.Thenumberofwhitefliesintroducedindisease-freecassavawas 5,10and20andthefeedingperiod(inoculation)ondisease-freecassavawas2,6,12and24hrs.Thiswasreplicatedforthreetimesand 10 plant/replication.To identify the transmission manner via cuttings, cuttings from symptomatic and asymptomatic plants of KM94,HL-S11and KM419planted in Dong Nai province were grown in insect resistant cages and caculate the number of diseased plants. The results indicated that viruliferousB.tabaciadultstransmittedSLCMVwithvariousdegreesofefficiencydependingonthenumberofadultsusedtotransmitandfeeding duration. The disease incidence ranged from 25.0-90.0%. Symptoms started from the top leaves. The latent period ranged from 20 to 25 days.After20-30daysofplantingtheCMD-infectedKM94,HL-S11andKM419varieties,itbegantoshowtypicalsymptomsofCMDwithleafcurl,wrinkling,mosaicandinconsistentwithdiseaserateof100%;meanwhile,inthecontroltreatmentthatusinghealthycuttingsfromthesamevarietiesshowednosymptoms.AllthetestedplantsweresubjectedtoPCRanalysisusingprimerpairSLCMV-A-F1/SLCMV-A-R2,directsequencingandDNAanalysis.TheallsymptomaticplantswerepositivewithSLCMV.ThestudyhasprovidedessentialinformationonthetransmissionofSLCMVviaeitherplantingmaterialsorthewhiteflyvectorthatwillhelptounderstandthespreadofSLCMVinthefieldandfacilitatethepredictionofvirusepidemicsinVietNam.
