title: FaGAST2, a strawberry ripening-related gene, acts together with FaGAST1 to determine cell size of the fruit receptacle.
abstract: Numerous GAST-like genes have been reported in higher plants, but only one GAST-like gene (FaGAST1) has been described in strawberry so far. Herein, we have identified a novel strawberry FaGAST gene (FaGAST2) whose expression showed an increase throughout fruit receptacle development and ripening, coinciding with those stages where a decrease in fruit expansion processes (G3-W and R-OR stages) occurs. FaGAST2 only shares 31% and 15.7% amino acid and nucleotide sequence homology, respectively, with the previously reported FaGAST1 gene, but both genes contain a signal peptide and a highly conserved GASA domain (cysteine-rich domain) in the C-terminal region. FaGAST2 expression is mainly confined to the fruit receptacle and is not regulated by auxins, GA(3) or ABA, but is regulated by ethephon, an intracellular generator of ethylene. In addition, the expression of the FaGAST2 gene also increased under oxidative stress conditions (H(2)O(2) or Colletotrichum acutatum infection), suggesting a direct role for FaGAST2 protein in reactive oxygen species scavenging during fruit growth and ripening and during fungal infection. On the other hand, the overexpression of the FaGAST2 gene in different transgenic lines analyzed caused a delay in the growth of strawberry plants and a reduction in the size of the transgenic fruits. The histological studies performed in these fruits showed that their parenchymal cells were smaller than those of the controls, supporting a relationship between FaGAST2 gene expression, strawberry fruit cell elongation and fruit size. However, transitory silencing of FaGAST2 gene expression through RNA interference approaches revealed an increase in FaGAST1 expression, but no changes in fruit cell size were observed. These results support the hypothesis that both genes must act synergistically to determine fruit cell size during fruit development and ripening.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Edificio Severo Ochoa C-6, Campus Universitario de Rabanales y Campus de Excelencia Internacional Agroalimentario CeiA3, Universidad de Córdoba, Córdoba, Spain.
authors.forename: Enriqueta
authors.initials: E
authors.lastname: Moyano-Cañete
authors.forename: María L
authors.initials: ML
authors.lastname: Bellido
authors.forename: Nicolás
authors.initials: N
authors.lastname: García-Caparrós
authors.forename: Laura
authors.initials: L
authors.lastname: Medina-Puche
authors.forename: Francisco
authors.initials: F
authors.lastname: Amil-Ruiz
authors.forename: José A
authors.initials: JA
authors.lastname: González-Reyes
authors.forename: José L
authors.initials: JL
authors.lastname: Caballero
authors.forename: Juan
authors.initials: J
authors.lastname: Muñoz-Blanco
authors.forename: Rosario
authors.initials: R
authors.lastname: Blanco-Portales
mesh_terms: D048429:Cell Size; D020231:Colletotrichum / Q000472:pathogenicity; D031985:Fragaria / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology; D005638:Fruit / Q000235:genetics* / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000494:pharmacology; D018384:Oxidative Stress; D010802:Phylogeny; D059828:Plant Cells / Q000378:metabolism / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D007210:Indoleacetic Acids; D009943:Organophosphorus Compounds; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; C005073:ethephon