Carotenepigmentsinflowersandfruitsaredistinctfeaturesrelatedtofitnessadvantagessuchasattractinginsectsforpollinationandbirdsforseeddispersal.Inpapaya,thefleshcolorofthefruitisconsideredaqualitytraitthatcorrelateswithnutritionalvalueandislinkedtoshelf-lifeofthefruit.Toelucidatethecarotenoidbiosynthesispathwayinpapaya,wetookacandidategeneapproachtoclonethelycopeneβ-cyclasegene,LCY-B.ApapayaLCY-Bortholog,cpLCY-B,wassuccessfullyidentifiedfrombothcDNAandbacterialartificialchromosome(BAC)librariesandcompletegenomicsequencewasobtainedfromthepositiveBACincludingthepromoterregion.ThiscpLCY-Bshared80%aminoacididentitywithcitrusLCY-B.However,fullgenomicsequencesfrombothyellow-andred-fleshedpapayawereidentical.Quantitativereal-timePCR(qPCR)revealedsimilarlevelsofexpressionatsixdifferentmaturingstagesoffruitsforbothyellow-andred-fleshedgenotypes.FurtherexpressionanalysesofcpLCY-Bshowedthatitsexpressionlevelswereseven-andthree-foldhigherinleavesand,respectively,flowersthaninfruits,suggestingthatcpLCY-Bisdown-regulatedduringthefruitripeningprocess.
