TheplasmidofpCDMARUBA-Hyg,whichcontainedtwoinsect-resistancegenes,sbk(modifiedfromCry1A(c))andsck(modifiedfromCpTI),wastransformedintoanAgrobacteriumEHA105forinfectionofthecalliofasuperjaponicariceNanjing45.Primarily,usingpolymerasechainreaction(PCR)detectionwiththeprimersofsbkandsckgenes,42positivetransgenicplantsthatweremarker-freeandcontainedthetwotargetgeneswereselectedfrom97regeneratedplants.Resultsofsouthern-blottingindicatedthat23,11,5,2and1plantshadone,two,three,fourandfivecopiesofthetransformedgenes,respectively.AnalysisofreversetranscriptionPCR(RT-PCR)andBtgenetestingpapershowedthat28T3generationplantsderivedfromfourtransgenicplantshavingasinglecopywereinsect-resistant.Feedingexperimentwithricestemborerrevealedthattheinsectresistancewasgreatlyincreasedwiththelarvamortalityrangingfrom94%to100%.Inaddition,amongthetransgenicplants,threeT3transgenicplantspossessedsomedesirablecharacteristicsforbreedingandproduction,suchasplantheight,seed-settingrate,1000-grainweightandlarvamortality.ThemechanismofinsectresistanceofBtgeneanditsapplicationinricetransgenicresearchwerealsobrieflydiscussed.
