title: Molecular cloning and characterization of a ripening-induced polygalacturonase related to papaya fruit softening.
abstract: Pulp softening is one of the most remarkable changes during ripening of papaya (Carica papaya) fruit and it is a major cause for post-harvest losses. Although cell wall catabolism has a major influence on papaya fruit, quality information on the gene products involved in this process is limited. A full-length polygalacturonase cDNA (cpPG) was isolated from papaya pulp and used to study gene expression and enzyme activity during normal and ethylene-induced ripening and after exposure of the fruit to 1-MCP. Northern-blot analysis demonstrated that cpPG transcription was strongly induced during ripening and was highly ethylene-dependent. The accumulation of cpPG transcript was paralleled by enzyme activity, and inversely correlated to the pulp firmness. Preliminary in silico analysis of the cpPG genomic sequence revealed the occurrence of putative regulatory motifs in the promoter region that may help to explain the effects of plant hormones and non-abiotic stresses on papaya fruit firmness. This newly isolated cpPG is an important candidate for functional characterization and manipulation to control the process of pulp softening during papaya ripening.
authors.affiliation: Laboratório de Química, Bioquímica e Biologia Molecular de Alimentos, Departamento de Alimentos e Nutrição Experimental, FCF, Universidade de São Paulo, Bloco 14, CEP 05508-900, São Paulo, SP, Brazil.
authors.forename: João Paulo
authors.initials: JP
authors.lastname: Fabi
authors.forename: Beatriz Rosana
authors.initials: BR
authors.lastname: Cordenunsi
authors.forename: Graham B
authors.initials: GB
authors.lastname: Seymour
authors.forename: Franco M
authors.initials: FM
authors.lastname: Lajolo
authors.forename: João Roberto Oliveira
authors.initials: JR
authors.lastname: do Nascimento
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D029441:Carica / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D003521:Cyclopropanes; D018076:DNA, Complementary; D005030:Ethylenes; D005638:Fruit / Q000201:enzymology* / Q000235:genetics; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008969:Molecular Sequence Data; D010940:Plant Proteins; D011096:Polygalacturonase / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D003521:Cyclopropanes; D018076:DNA, Complementary; D005030:Ethylenes; D010940:Plant Proteins; D012333:RNA, Messenger; C036216:ethylene; D011096:Polygalacturonase; C412563:1-methylcyclopropene