简介:Twostarch-branchingenzyme(SBE)inrice,isknowntobeakeyenzymeinamylopectinbiosynthesis.ThecDNAoftwoSBE(starch-branchingenzyme)genesSheIandShedencodingSBEⅠandSBEⅢ(twomajorisoformsinrice)wereclonedbyanimprovedRT-PCRtechnique,fromatemplatecDNAlibray,derivedfromthetotalmRNAsextractedfromtheimmatureseedsofajaponicariceWuyunjing7.DNAsequenceanalysisshowedthatthesizeoftheclonedSheIandShedcDNAswere2490and2481bplong,respectively,includingtheirentirecodingsequences.ComparisonanalysisindicatedthatthenucleotidesequenceofShe3wasthesameasthatofshed(GenbankAccessionNo.D16201)asreportedpreviously.Therewereonlyfourbase-pairsdifference,whichresultedinchangesoftwodeducedaminoacidsbetweentheclonedShe1cDNAandthereportedshe1(GenbankAccessionNo.D11082).TheclonedSheIandShedcDNAsmakeitpossibletoimprovericestarchqualitythroughgeneticengineering.