title: Overexpression of PhEXPA1 increases cell size, modifies cell wall polymer composition and affects the timing of axillary meristem development in Petunia hybrida.
abstract: • Expansins are cell wall proteins required for cell enlargement and cell wall loosening during many developmental processes. The involvement of the Petunia hybrida expansin A1 (PhEXPA1) gene in cell expansion, the control of organ size and cell wall polysaccharide composition was investigated by overexpressing PhEXPA1 in petunia plants. • PhEXPA1 promoter activity was evaluated using a promoter-GUS assay and the protein's subcellular localization was established by expressing a PhEXPA1-GFP fusion protein. PhEXPA1 was overexpressed in transgenic plants using the cauliflower mosaic virus (CaMV) 35S promoter. Fourier transform infrared (FTIR) and chemical analysis were used for the quantitative analysis of cell wall polymers. • The GUS and GFP assays demonstrated that PhEXPA1 is present in the cell walls of expanding tissues. The constitutive overexpression of PhEXPA1 significantly affected expansin activity and organ size, leading to changes in the architecture of petunia plants by initiating premature axillary meristem outgrowth. Moreover, a significant change in cell wall polymer composition in the petal limbs of transgenic plants was observed. • These results support a role for expansins in the determination of organ shape, in lateral branching, and in the variation of cell wall polymer composition, probably reflecting a complex role in cell wall metabolism.
authors.affiliation: Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Zenoni
authors.affiliation: Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy.
authors.forename: Marianna
authors.initials: M
authors.lastname: Fasoli
authors.affiliation: Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy.
authors.forename: Giovanni Battista
authors.initials: GB
authors.lastname: Tornielli
authors.affiliation: Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Dal Santo
authors.affiliation: Computer Science Department, University of Verona, Strada le Grazie 15, 37134 Verona, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Sanson
authors.affiliation: Department of Molecular Plant Physiology IWWR, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: de Groot
authors.affiliation: Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Sordo
authors.affiliation: Environment and Territory Science Department, University of Milano-Bicocca, Piazza delle Scienze 1, 20133 Milano, Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Citterio
authors.affiliation: Computer Science Department, University of Verona, Strada le Grazie 15, 37134 Verona, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Monti
authors.affiliation: Department of Biotechnology, University of Verona, Strada le Grazie 15, 37134 Verona, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Pezzotti
mesh_terms: D017796:Caulimovirus / Q000235:genetics; D048429:Cell Size; D002473:Cell Wall / Q000235:genetics / Q000502:physiology*; D035264:Flowers / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D008027:Light; D018519:Meristem / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D009929:Organ Size / Q000502:physiology; D032306:Petunia / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects; D010641:Phenotype; D018515:Plant Leaves / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D011108:Polymers / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins; D013997:Time Factors
chemical_list: D010940:Plant Proteins; D011108:Polymers; D011993:Recombinant Fusion Proteins; C095825:expansin protein, plant