Regulation of stress-induced phospholipid hydroperoxide glutathione peroxidase expression in citrus

• Published in: Planta 1999-10, Vol.209 (4), p.469-477
• Main Authors: Avsian-Kretchmer, O, Eshdat, Y, Gueta-Dahan, Y, Ben-Hayyim, G
• Format: Article
• Language: English
• Subjects: abscisic acid; Agronomy. Soil science and plant productions; air temperature; Biological and medical sciences; Cell lines; chemical constituents of plants; Citrus sinensis; Classical and quantitative genetics. Population genetics. Molecular genetics; cold stress; Fundamental and applied biological sciences. Psychology; gene expression; Gene expression regulation; Gene induction; Generalities. Genetics. Plant material; genes; genetic regulation; Genetics and breeding of economic plants; heat stress; Inductive reasoning; inhibitors; Messenger RNA; Molecular genetics; Non agrochemicals pollutants; oxidation; Oxidative stress; peroxidases; Phytopathology. Animal pests. Plant and forest protection; Plants; Pollution effects and side effects of agrochemicals on crop plants and forest trees. Other anthropogenic factors; Pollution effects. Side effects of agrochemicals; ribosomal RNA; Salt tolerance; Salts; sodium chloride; substrates; Table salt; transcription (genetics)
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s004250050750

Recent findings in our laboratory showed that in citrus cells, salt treatment induced the accumulation of mRNA and a protein corresponding to phospholipid hydroperoxide glutathione peroxidase (PHGPX), an enzyme active in the cellular antioxidant system. The protein and its encoding gene, csa, were isolated and characterized, and the expected enzymatic activity was demonstrated (G.Ben-Hayyim et al., 1993, Plant Sci. 88: 129-140; D. Holland et al., 1993, Plant Mol. Biol. 21: 923-927; D. Holland et al., 1994, FEBS Lett. 337: 52-55; T. Beeor-Tzahar et al., 1995, FEBS Lett. 366: 151-155). In an attempt to find out how salt induces the expression of an antioxidant enzyme, the regulation of PHGPX in citrus cells was studied at both the mRNA transcript and the protein levels. A high and transient response at the csa mRNA level was observed after 4-7 h of exposing salt-sensitive cells to NaCl, or abscisic acid, whereas no response could be detected in the salt-tolerant cells under the same conditions. tert-Butylhydroperoxide, a substrate of PHGPX, induced csa mRNA transcripts after only 2 h, and abolished the differential response between salt-sensitive and salt-tolerant cells. On the basis of these results and those obtained under heat and cold stresses, it is suggested that csa is directly induced by the substrate of its encoded enzyme PHGPX, and that salt induction occurs mainly via the production of reactive oxygen species and hydroperoxides.