title: Expression analysis and functional characterization of apple MdVHP1 gene reveals its involvement in Na(+), malate and soluble sugar accumulation.
abstract: The vacuolar H(+)-pyrophosphatase (VHP) is a proton pump, which energizes transport across the tonoplast. The contributions of VHP to ion, organic acid and sugar storage are unclear in fruit. Here we characterized the role of an apple vacuolar H(+)-pyrophosphatase gene (MdVHP1) in Na(+), malate and soluble sugar accumulation. MdVHP1 expression was consistent with VHP activities in apple fruits at most developmental stages, and highly significantly correlated with Na(+) concentration during fruit development. In apple fruits treated in vitro (i.e., fruit-bearing branches were cultured in Hoagland solution containing each of salt, malate and sucrose, respectively, or irradiated by blue light), MdVHP1 expression was significantly correlated with Na(+) and malate transporter genes MdNHX1 and MdtDT, while subunit A of the vacuolar H(+)-ATPase (MdVHA-A) was significantly correlated with MdtDT and sucrose transporter gene (MdSUT1). In addition, MdVHP1 overexpression noticeably promoted Na(+) and malate accumulation, but slightly increased soluble sugar accumulation in transgenic apple callus and tomato fruit, partially by regulating transporter genes MdNHX1, MdtDT and MdSUT1. Taken together, it appears that MdVHP1 favorably contributes to Na(+), malate and soluble sugar accumulation in apple fruit.
authors.affiliation: State Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China.
authors.forename: Yu-Xin
authors.initials: YX
authors.lastname: Yao
authors.forename: Qing-Long
authors.initials: QL
authors.lastname: Dong
authors.forename: Chun-Xiang
authors.initials: CX
authors.lastname: You
authors.forename: Heng
authors.initials: H
authors.lastname: Zhai
authors.forename: Yu-Jin
authors.initials: YJ
authors.lastname: Hao
mesh_terms: D060054:Agrobacterium / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D057075:Enzyme Assays; D005638:Fruit / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D043564:Inorganic Pyrophosphatase / Q000235:genetics / Q000378:metabolism*; D008027:Light; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D008293:Malates / Q000378:metabolism* / Q000494:pharmacology; D027845:Malus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D012965:Sodium Chloride / Q000378:metabolism* / Q000494:pharmacology; D013395:Sucrose / Q000378:metabolism / Q000494:pharmacology; D019076:Transgenes
chemical_list: D008293:Malates; D010940:Plant Proteins; D012965:Sodium Chloride; D013395:Sucrose; C030298:malic acid; D043564:Inorganic Pyrophosphatase