Aldehyde oxidase and xanthine dehydrogenase in a flacca tomato mutant with deficient abscisic acid and wilty phenotype

Moshe Sagi, Robert Fluhr, S. Herman Lips

Research output: Contribution to journalArticlepeer-review

81 Scopus citations

Abstract

The flacca tomato (Lycopersicon esculentum) mutant displays a wilty phenotype as a result of abscisic acid (ABA) deficiency. The Mo cofactor (MoCo)-containing aldehyde oxidases (AO; EC 1.2.3.1) are thought to play a role in the final oxidation step required for ABA biosynthesis. AO and related MoCo-containing enzymes xanthine dehydrogenase (XDH; EC 1.2.1.37) and nitrate reductase (EC 1.6.6.1) were examined in extracts of the flacca tomato genotype and of wild-type (WT) roots and shoots. The levels of MoCo were found to be similar in both genotypes. No significant XDH or AO (MoCo-containing hydroxylases) activities were detected in flacca leaves; however, the mutant exhibited considerable MoCo-containing hydroxylase activity in the roots, which contained notable amounts of ABA. Native western blots probed with an antibody to MoCo-containing hydroxylases revealed substantial, albeit reduced, levels of cross-reactive protein in the flacca mutant shoots and roots. The ABA xylem-loading rate was significantly lower than that in the WT, indicating that the flacca is also defective in ABA transport to the shoot. Significantly, in vitro sulfurylation with Na2S reactivated preexisting XDH and AO proteins in extracts from flacca, particularly from the shoots, and superinduced the basal-level activity in the WT extracts. The results indicate that in flacca, MoCo-sulfurylase activity is impaired in a tissue-dependent manner.

Original languageEnglish
Pages (from-to)571-577
Number of pages7
JournalPlant Physiology
Volume120
Issue number2
DOIs
StatePublished - 1 Jan 1999

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

Fingerprint

Dive into the research topics of 'Aldehyde oxidase and xanthine dehydrogenase in a flacca tomato mutant with deficient abscisic acid and wilty phenotype'. Together they form a unique fingerprint.

Cite this