PqqE gene as a molecular marker of phosphate solubilizing bacteria associated to peanut plants.

ANZUAY MS, CHIATTI MH, LUDUEÑA LM, DALMASSO R, FERNANDEZ VALDÉS P, ANGELINI JG, TAURIAN T.

Los Cocos

Congreso; XVIII SAMIGE; 2022

nArgentinianpeanutagriculturalarea,lowvaluesofsoilphosphorus(P)weredetected.Withinsoilbacteria,somearecapableofexercisebeneficialeffectsforplantsgrowth,forexamplethesolubilizationofinsolublephosphatesthatprovidesPtoplants.ThisnutrientcanbereleasedfrominorganicPcompoundsbythesynthesisoforganicacidssuchasgluconicacid(GA).TheproductionofGAisthemainmechanismbywhichGram-negativebacteriasolubilizeinsolubleinorganicsoilPsources.Thisorganicacidisproducedbyphosphatesolubilizingbacteria(PBS)bytheactionofglucosedehydrogenase(GDH)-PQQholoenzyme.TheroleofPQQcofactorinthisoxidativepathwayisessential.PreviousresultsfromourlaboratoryindicatedthatalargenumberofGram-negativePSBcontainintheirgenomethepqqEgene,oneoftheessentialgenesinvolvedinPQQbiosynthesis.Besides,thepresenceofthisgenewasdetectedinPSBfrommixedsamplesofbacterialcultures.TheobjectiveofthisstudywastoanalyzethepresenceofpqqEgeneinrhizosphericsoilsamplesinpresenceandabsenceofpeanutplantsandinoculatedornotwithPSB.DNAwasisolatedfromsamplesofrhizosphericsoilassociatedtofieldsofpeanutplantsfromRíoCuarto(SRRC),SanSevero(SRSS),LaCarlota(SRLC),Reducción(SRR),Gigena(SRG),SanAmbrosio(SRSA).Also,rhizosphericsoilsamplesobtainedfromamicrocosmsassaywithpeanutplantsgrowinginSRRCinoculated(SRPI)ornot(SRPNI)withSS-ER-24strainwereanalyzed.SRRCwithoutplantsandinoculatedwithSS-ER-24strain(SRI)andnon-rhizosphericsoilwerealsoanalyzed(SNR).PCR-pqqEwasperformedusingtwopairsofprimersdesignedinourlaboratory.ThepairpqqEF-317/1019thatamplifypqqEgenefromseveralbacteriaofdifferentgeneraandthespecificpairpqqEPS1/pqqEPS2designedtoamplifythefragmentinthegenusPseudomonas.ThePCR-pqqEproductsweresenttoMacrogenInc.laboratories.TheexpectedPCRproductsofamplificationusingthespecificprimerswereobservedinallsoilsamplesanalyzed,withexceptionofSRLC.Ontheotherhand,byusingthepairpqqEF-317/1019theamplificationoftheexpectedfragmentwasobservedinthesamplesSRRC,SRSS,SRR,SRG,SRSAandSRI.ThepqqEsequencesfromthedifferentsamplesshowedahighidentitywithsequencesofpqqEbacterialgenefromgeneraPseudomonasinthosePCRfragmentsobtainedwithspecificprimers.ThesequencesofthefragmentsobtainedwithdegeneratedprimersshowedidentitywithsequencesbelongingtothegeneraPseudomonas,Serratia,Pantoea,Enterobacter,KlebsiellaandAcinetobacter.ItispossibletoconcludethatpqqEgenewasdetectedinrhizosphericandnon-rhizosphericsoilsamples,rhizosphericsoilwithpeanutplantsinoculatedwithBSPandnon-inoculated.Therefore,thepqqEgeneisapotentialmolecularmarkerforGram-negativebacteriawithaphosphate-solubilizingphenotypeinsoilsamples.