title: Activity and expression of  polygalacturonase vary at different fruit ripening stages of  sweet pepper cultivars.
abstract: Activity  and expression of polygalacturonase (PG), a hydrolytic enzyme involved in  ultrastructural changes in the pericarp of sweet pepper (Capsicum annaum),  were investigated at different ripening stages of the pepper cultivars Mandi  and Talanduo. Molecular cloning of CaPG was carried out by constructing  a cDNA library from three stages of fruit ripening. Morphological  determination, PG assay, RT-PCR, and ultrastructural studies were used to quantify  changes in CaPG gene expression in the pericarp from green, color change  and fully ripened stages. We found that CaPG gene expression, PG  activity and striking changes in the structure of the cell wall occurred with  the transition of ripening stages. CaPG gene expression was high  (obvious PCR products) in mature and ripened stages of both cultivars; however,  the CaPG gene was not expressed in preclimacteric fruits or vegetative  tissues. We conclude that developmental regulation of CaPG gene  expression is instrumental for sweet pepper fruit ripening; its expression  during development leads to dissolution of middle lamella and eventually  disruption of the fully ripened cell wall.
authors.affiliation: College of Horticulture, Northwest A & F University, Yangling, Shaanxi, P.R. China.
authors.forename: S S
authors.initials: SS
authors.lastname: Ahmed
authors.forename: Z-H
authors.initials: ZH
authors.lastname: Gong
authors.forename: M A
authors.initials: MA
authors.lastname: Khan
authors.forename: Y-X
authors.initials: YX
authors.lastname: Yin
authors.forename: W-L
authors.initials: WL
authors.lastname: Guo
authors.forename: J
authors.initials: J
authors.lastname: Imran
mesh_terms: D002212:Capsicum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure; D002473:Cell Wall / Q000201:enzymology / Q000235:genetics / Q000648:ultrastructure; D003001:Cloning, Molecular; D005638:Fruit / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D046529:Microscopy, Electron, Transmission; D011096:Polygalacturonase / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D011096:Polygalacturonase