title: Transgenic expression of a putative calcium transporter affects the time of Arabidopsis flowering.
abstract: PPF1 is a gibberellin-induced, vegetative growth-specific gene, first isolated from short-day (SD)-grown G2 pea plants. In the current work, we found that transgenic Arabidopsis plants overexpressing the PPF1 gene (PPF1 (+)) flowered much later and had a significantly longer lifespan compared to control plants, whereas suppression of this gene (PPF1 (-)) resulted in a very rapid reproductive cycle. Western blotting analyses of PPF1 (+) and (-) plant lines revealed a positive correlation between the amount of antibody-reactive protein and the time of flowering. Green fluorescent protein (GFP) co-expression assays showed that the PPF1 protein is likely localized in chloroplast membranes. Transgenic expression of PPF1 affected the calcium storage capacities since chloroplasts isolated from PPF1 (+) plants contained high Ca2+ levels while chloroplasts of PPF1 (-) plants contained very low amounts of calcium ion. Using Novikoff human hepatoma cells, we demonstrated that expression of PPF1 leads to a significant inward calcium ion current that was absent in untransformed cells. We conclude that, as a putative calcium ion carrier, PPF1 affects the flowering time of higher plants by modulating Ca2+ storage capacity within chloroplasts.
authors.affiliation: The National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Dayong
authors.initials: D
authors.lastname: Wang
authors.forename: Yunjian
authors.initials: Y
authors.lastname: Xu
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.forename: Xuemei
authors.initials: X
authors.lastname: Hao
authors.forename: Keming
authors.initials: K
authors.lastname: Cui
authors.forename: Fangzhen
authors.initials: F
authors.lastname: Sun
authors.forename: Yuxian
authors.initials: Y
authors.lastname: Zhu
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D045744:Cell Line, Tumor; D002736:Chloroplasts / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D018532:Pisum sativum / Q000235:genetics; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D030821:Plants, Genetically Modified; D013997:Time Factors; D019076:Transgenes / Q000235:genetics
chemical_list: D002135:Calcium-Binding Proteins; C111031:PPF-1 protein, Pisum sativum; D010940:Plant Proteins; D002118:Calcium