title: Gene expression  and enzymatic activity of pectin methylesterase during fruit development and  ripening in Coffea arabica L.
abstract: Coffee  quality is directly related to the harvest and post harvest conditions.  Non-uniform maturation of coffee fruits, combined with inadequate harvest, negatively  affects the final quality of the product. Pectin methylesterase (PME) plays an  important role in fruit softening due to the hydrolysis of methylester groups  in cell wall pectins. In order to characterize the changes occurring during  coffee fruit maturation, the enzymatic activity of PME was measured during  different stages of fruit ripening. PME activity progressively increased from  the beginning of the ripening process to the cherry fruit stage. In silico analysis  of expressed sequence tags of the Brazilian Coffee Genome Project database  identified 5 isoforms of PME. We isolated and cloned a cDNA homolog of  PME for further characterization. CaPME4 transcription was analyzed in  pericarp, perisperm, and endosperm tissues during fruit development and ripening  as well as in other plant tissues. Northern blot analysis revealed increased  transcription of CaPME4 in the pericarp 300 days after flowering. Low  levels of CaPME4 mRNAs were observed in the endosperm 270 days after  flowering. Expression of CaPME4 transcripts was strong in the branches  and lower in root and flower tissues. We showed that CaPME4 acts  specifically during the later stages of fruit ripening and possibly contributes  to the softening of coffee fruit, thus playing a significant role in pectin  degradation in the fruit pericarp.
authors.affiliation: Laboratório de Biotecnologia Vegetal, Instituto Agronômico do Paraná, Londrina, PR, Brasil.
authors.forename: S M B
authors.initials: SM
authors.lastname: Cação
authors.forename: T F
authors.initials: TF
authors.lastname: Leite
authors.forename: I G F
authors.initials: IG
authors.lastname: Budzinski
authors.forename: T B
authors.initials: TB
authors.lastname: dos Santos
authors.forename: M B S
authors.initials: MB
authors.lastname: Scholz
authors.forename: V
authors.initials: V
authors.lastname: Carpentieri-Pipolo
authors.forename: D S
authors.initials: DS
authors.lastname: Domingues
authors.forename: L G E
authors.initials: LG
authors.lastname: Vieira
authors.forename: L F P
authors.initials: LF
authors.lastname: Pereira
mesh_terms: D000595:Amino Acid Sequence; D015152:Blotting, Northern; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D040503:Coffea / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development*; D019295:Computational Biology; D017124:Conserved Sequence / Q000235:genetics; D020224:Expressed Sequence Tags; D005638:Fruit / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development*; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D017343:Genes, Plant / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase