Explosive Tandem and Segmental Duplications of Multigenic Families in Eucalyptus grandis

laudon, kenneth. c;

Plant organisms contain a large number of genes belonging to numerous multigenic families whose evolution size reflects some functional constraints. Sequences from eight multigenic families, involved in biotic and abiotic responses, have been analyzed in Eucalyptus grandis and compared with A rabidopsisthaliana. Two transcription factor families APETALA2(AP2)/ethylene responsive factor and GRAS, two auxin transporter families PIN-FORMED and AUX/LAX, two oxidoreductase families (ascorbate peroxidases [APx] and Class III peroxidases [CIIIPrx]), and two families of protective molecules late embryo genesis abundant (LEA) and DNAj were annotated in expert and exhaustive manner. Many recent tandem duplications leading to the emergence of species-specific gene clusters and the explosion of the gene numbers have been observed for the AP2, GRAS, LEA, PIN, and CIII Prxin E.grandis,whilethe APx, the AUX/LAX and DNAj are conserved between species. Although no direct evidence has yet demonstrated the roles of these recent duplicated genes observed in E.grandis, thiscouldindicatetheirputativeimplicationsinthemorphologicalandphysiological characteristicsofE.grandis,andbethekeyfactorforthesurvivalofthisnondormantspecies.Globalanalysisofkeyfamilieswouldbea good criterion to evaluate the capabilities of some organisms to adapt to environmental variations