title: Characterization of two functional phosphoenolpyruvate/phosphate translocator (PPT) genes in Arabidopsis--AtPPT1 may be involved in the provision of signals for correct mesophyll development.
abstract: The Arabidopsis thaliana chlorophyll a/b-binding protein underexpressed 1 (cue1) mutant shows a reticulate leaf phenotype and is defective in a plastidic phosphoenolpyruvate (PEP)/phosphate translocator (AtPPT1). A functional AtPPT1 providing plastids with PEP for the shikimate pathway is therefore essential for correct leaf development. The Arabidopsis genome contains a second PPT gene, AtPPT2. Both transporters share similar substrate specificities and are therefore able to transport PEP into plastids. The cue1 phenotype could partially be complemented by ectopic expression of AtPPT2 but obviously not by the endogeneous AtPPT2. Both genes are differentially expressed in most tissues: AtPPT1 is mainly expressed in the vasculature of leaves and roots, especially in xylem parenchyma cells, but not in leaf mesophyll cells, whereas AtPPT2 is expressed ubiquitously in leaves, but not in roots. The expression profiles are corroborated by tissue-specific transport data. As AtPPT1 expression is absent in mesophyll cells that are severely affected in the cue1 mutant, we propose that the vasculature-located AtPPT1 is involved in the generation of phenylpropanoid metabolism-derived signal molecules that trigger development in interveinal leaf regions. This signal probably originates from the root vasculature where only AtPPT1, but not AtPPT2, is present.
authors: Botanisches Institut der Universität zu Köln, Gyrhofstrasse 15, D-50931 Köln, Germany.
authors: Silke
authors: S
authors: Knappe
authors: Tanja
authors: T
authors: Löttgert
authors: Anja
authors: A
authors: Schneider
authors: Lars
authors: L
authors: Voll
authors: Ulf-Ingo
authors: UI
authors: Flügge
authors: Karsten
authors: K
authors: Fischer
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D017931:DNA Primers; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005966:Glucuronidase / Q000235:genetics; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D014176:Protein Biosynthesis; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D029681:Arabidopsis Proteins; D017931:DNA Primers; D026901:Membrane Transport Proteins; C481826:phosphate translocator 1, Arabidopsis; D005966:Glucuronidase