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TRANSPARENT TESTA 13 is a tonoplast P 3A ‐ ATP ase required for vacuolar deposition of proanthocyanidins in Arabidopsis thaliana seeds
Author(s) -
Appelhagen Ingo,
Nordholt Niclas,
Seidel Thorsten,
Spelt Kees,
Koes Ronald,
Quattrochio Francesca,
Sagasser Martin,
Weisshaar Bernd
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12854
Subject(s) - vacuole , mutant , arabidopsis thaliana , microbiology and biotechnology , biochemistry , wild type , biology , v atpase , atpase , proton pump , vanadate , arabidopsis , chemistry , cytoplasm , gene , enzyme
Summary Intracellular pH homeostasis is essential for all living cells. In plants, pH is usually maintained by three structurally distinct and differentially localized types of proton pump: P‐type H + ‐ ATP ases in the plasma membrane, and multimeric vacuolar‐type H + ‐ ATP ases (V‐ ATP ases) and vacuolar H + ‐pyrophosphatases (H + ‐ PP ases) in endomembranes. Here, we show that reduced accumulation of proanthocyanidins ( PA s) and hence the diminished brown seed coloration found in the Arabidopsis thaliana mutant transparent testa 13 ( tt13 ) is caused by disruption of the gene encoding the P 3A ‐ ATP ase AHA 10. Identification of the gene encoded by the tt13 locus completes the molecular characterization of the classical set of transparent testa mutants. Cells of the tt13 seed coat endothelium do not contain PA ‐filled central vacuoles as observed in the wild‐type. tt13 phenocopies tt12 , a mutant that is defective in vacuolar import of the PA precursor epicatechin. Our data show that vacuolar loading with PA precursors depends on TT 13. Consistent with the tt13 phenotype, but in contrast to other isoforms of P‐type H + ‐ ATP ases, TT 13 localizes to the tonoplast. PA accumulation in tt13 is partially restored by expression of the tonoplast localized H + ‐ PP ase VHP 1. Our findings indicate that the P 3A ‐ ATP ase TT 13 functions as a proton pump in the tonoplast of seed coat endothelium cells, and generates the driving force for TT 12‐mediated transport of PA precursors to the vacuole.