A plasma membrane H+-ATPase is required for the formation of proanthocyanidins in the seed coat endothelium of Arabidopsis thaliana

Ivan R. Baxter, Jeffery C. Young, Gordon Armstrong, Nathan Foster, Naomi Bogenschutz, Tatiana Cordova, Wendy Ann Peer, Samuel P. Hazen, Angus S. Murphy, Jeffrey F. Harper

Research output: Contribution to journalArticlepeer-review

185 Scopus citations


The plasma membrane in plant cells is energized with an electrical potential and proton gradient generated through the action of H+ pumps belonging to the P-type ATPase super-family. The Arabidopsis genome encodes 11 plasma membrane H+ pumps. Auto-inhibited H +-ATPase isoform 10 (AHA10) is expressed primarily in developing seeds. Here we show that four independent gene disruptions of AHA10 result in seed coats with a transparent testa (tt) phenotype (light-colored seeds). A quantitative analysis of extractable flavonoids in aha10 seeds revealed an ≈100-fold reduction of proanthocyanidin (PA), one of the two major end-product pigments in the flavonoid biosynthetic pathway. In wild-type seed coat endothelial cells, PA accumulates in a large central vacuole. In aha10 mutants, the formation of this vacuole is impaired, as indicated by the predominance of multiple small vacuoles observed by fluorescence microscopy using a vacuole-specific dye, 5-(and -6)-carboxy 2′,7′- dichlorofluorescein diacetate. A similar vacuolar defect was also observed for another tt mutant, tt12, a proton-coupled multidrug and toxic compound extrusion transporter potentially involved in loading provacuoles with a flavonoid intermediate required for PA production. The endothelial cells in aha10 mutants are otherwise healthy, as indicated by the lack of a significant decrease in (i) the accumulation of other flavonoid pathway end products, such as anthocyanins, and (ii) mRNA levels for two endothelium-specific transcripts (TT12 and BAN). Thus, the specific effect of aha10 on vacuolar and PA biogenesis provides genetic evidence to support an unexpected endomembrane function for a member of the plasma membrane H+-ATPase family.

Original languageEnglish
Pages (from-to)2649-2654
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number7
StatePublished - Feb 15 2005


  • Flavonoid
  • P-type ATPase
  • Proton pump


Dive into the research topics of 'A plasma membrane H+-ATPase is required for the formation of proanthocyanidins in the seed coat endothelium of Arabidopsis thaliana'. Together they form a unique fingerprint.

Cite this