ABSTRACT
The pxd mutant of Arabidopsis thaliana had a changed spectrum of anionic peroxidases: three anionic isoforms in the pxd mutant plant had the same enzymatic activity but relatively high electrophoretic mobility as compared to the analogous isoforms in the wild type plants. These isoforms were the most active anionic peroxidases and could be found in most plant organs. Genetic analysis showed that all three isoforms were controlled by the PXD gene. The activity of one isoform was affected by indolyl-3-acetic acid and other stress factors. Expressed sequence tags (EST) analysis of all putative peroxidase genes of A. thaliana revealed the group of the most actively and nonspecifically expressed genes. The promoter sequences of these genes were screened to find the cis-elements. We propose that the PXD gene encodes one of the nonspecific anionic peroxidases or a protein involved in posttranscriptional or posttranslational modification of the peroxidases.
Subject(s)
Arabidopsis Proteins/genetics , Arabidopsis/genetics , Gene Expression Regulation, Plant , Peroxidase/genetics , Anions , Arabidopsis/drug effects , Arabidopsis/metabolism , Arabidopsis Proteins/drug effects , Arabidopsis Proteins/metabolism , Electrophoresis, Polyacrylamide Gel , Expressed Sequence Tags , Indoleacetic Acids/pharmacology , Isoelectric Focusing , Isoenzymes/genetics , Isoenzymes/metabolism , Mutation , Peroxidase/chemistry , Peroxidase/metabolism , Plant Growth Regulators/pharmacology , Plant Shoots/enzymology , Promoter Regions, GeneticABSTRACT
Selective systems for screening Arabidopsis thaliana (L.) Heynh. mutants with altered sensitivity to the oxidative stress (OS) inductors norflurazon (NF), acifluorfen (AF), and plumbagin (PB) were developed and a collection of 28 mutants was obtained. Dwarf and necrotic forms predominated among the NF-tolerant mutants, while pigment mutants and those with changed root morphology prevailed among the AF-tolerant and PB-sensitive mutants, respectively. Genetic and biochemical analysis of certain mutants was performed; quantitative and qualitative changes in the content of superoxide dismutase and peroxidase isoforms have been revealed. These data, complemented by the data on the cross-tolerance (sensitivity) of the mutants to paraquat, indicate a correlation between tolerance to the OS inductors and the functions of antioxidant systems.
