Smallubiquitin-likemodifier(SUMO)-conjugatingenzymesareinvolvedinpost-translationalregulatoryprocessesineukaryotes,includingtheconjugationofSUMOpeptidestoproteinsubstrate(SUMOylation).SUMOylationplaysanimportantroleinimprovingplanttolerancetoabioticstresssuchassalt,drought,heatandcold.Herein,wereportedtheisolationofOsSCE1(LOC_Os10g39120)geneencodingaSUMO-conjugatingenzymefromrice(Oryzasativacv.Nipponbare)anditsfunctionalvalidationinresponsetodroughtstress.TheE2enzyme,OsSCE1,isoneofthreekeyenzymesinvolvedintheconjugationofSUMOtoitstargetproteins.ActivatedSUMOistransferredtothecysteineofanE2enzymeandthentothetargetlysineresidueofthesubstrate,withorwithoutthehelpofanE3SUMOligase.ExpressionofOsSCE1wasstronglyinducedbypolyethyleneglycol6000(PEG6000)treatment,whichsuggestedOsSCE1maybeinvolvedinthedroughtstressresponse.OverexpressionofOsSCE1(OsSCE1-OX)inNipponbarereducedthetolerancetodroughtstress.Conversely,thedroughttolerancewasslightlyimprovedbytheknockdownofOsSCE1(OsSCE1-KD).TheseresultswerefurthersupportedbymeasurementofprolinecontentinOsSCE1-OXandOsSCE1-KDtransgeniclinesunderinduceddroughtstress,whichshowedOsSCE1-KDtransgeniclinesaccumulatedhigherprolinecontentthanthewildtype,whereasOsSCE1-OXlinehadlowerprolinecontentthanthewildtype.ThesefindingssuggestedOsSCE1mayplayaroleasanegativeregulatorinresponsetodroughtstressinrice.
