New insights on the evolution of Leafy cotyledon1 (LEC1) type genes in vascular plants

摘要

NF-Yisaconservedoligomerictranscriptionfactorfoundinalleukaryotes.Inplants,thisregulatorevolvedwithabroaddiversificationofthegenescodingforitsthreesubunits(NF-YA,NF-YBandNF-YC).TheNF-YBmemberscanbedividedintoLeafyCotyledon1(LEC1)andnon-LEC1types.HerewepresentedacomparativegenomicstudyusingphylogeneticanalysestovalidateanevolutionarymodelfortheoriginofLEC-typegenesinplantsandtheiremergencefromnon-LEC1-typegenes.WeidentifiedLEC1-typemembersinallvascularplantgenomes,butnotinamoebozoa,algae,fungi,metazoaandnon-vascularplantrepresentatives,whichpresentexclusivelynon-LEC1-typegenesasconstituentsoftheirNF-YBsubunits.Thenon-synonymoustosynonymousnucleotidesubstitutionrates(Ka/Ks)betweenLEC1andnon-LEC1-typegenesindicatethepresenceofpositiveselectionactingonLEC1-typememberstothefixationofLEC1-specificaminoacidresidues.ThephylogeneticanalysesdemonstratedthatplantLEC1-typegenesareevolutionarydivergentfromthenon-LEC1-typegenesofplants,fungi,amoebozoa,algaeandanimals.OurresultspointtoascenarioinwhichLEC1-typegeneshaveoriginatedinvascularplantsaftergeneexpansioninplants.Wesuggestthatprocessesofneofunctionalizationand/orsubfunctionalizationwereresponsiblefortheemergenceofaversatileroleforLEC1-typegenesinvascularplants,especiallyinseedplants.LEC1-typegenesbesidesbeingphylogeneticdivergentalsopresentdifferentexpressionprofilewhencomparedwithnon-LEC1-typegenes.Altogether,ourdataprovidenewinsightsabouttheLEC1andnon-LEC1evolutionaryrelationshipduringthevascularplantevolution./p/div