Molecular characterization and expression of a cDNA encoding copper/zinc superoxide dismutase from cultured cells of cassava (

Abstract

A cDNA, mSOD1, encoding cytosolic copper/zinc superoxide dismutase (CuZnSOD) was cloned and characterized from cell cultures of cassava (Manihot esculenta Crantz) which produce a high yield of SOD. mSOD1 encodes a 152-amino acid polypeptide with a pI value of 5.84. Southern analysis using an mSOD1-specific probe indicated that a single copy of the mSOD1 gene is present in the cassava genome. The mSOD1 gene is highly expressed in cultured cells, as well as in intact stems and tuberous roots. It is expressed at a low level in leaves and petioles. Transcripts of mSOD1 were not detected in nontuberous roots. Transcriptional level of mSOD1 reaches a high level at stationary phase, and then sharply decreases during further culture. In excised cassava leaves, the mSOD1 gene responded to various stresses in different ways. The stresses tested included changes in temperature and exposure to stress-inducing chemicals. Levels of mSOD1 transcript increased dramatically a few hours after heat stress at 37 degrees C and showed a synergistic effect with wounding stress. Levels decreased in response to chilling stress at 4 degrees C and showed an antagonistic effect with wounding stress. The gene was induced by abscisic acid, ethephon, NaCl, sucrose, and methyl viologen. These results indicate that the mSOD1 gene is involved in the response to oxidative stress induced by environmental change.

Differential expression of six novel peroxidase cDNAs from cell cultures of sweetpotato in response to stress

“…Superoxide dismutase, an antioxidant enzyme, is also induced by various stresses (Bowler et al 1989;Lee et al 1999). When exposed to chilling stress, the mSOD gene encoding a cytosolic CuZnSOD of cassava (M. esculenta) was induced by 5 HAT, but then its expression declined to below the level seen in the control cultured at 25°C, also showing an antagonistic effect relative to culture stress ).…”

“…In previous studies, we established an efficient production system for POD and superoxide dismutase (SOD) using cell cultures of sweetpotato (Ipomoea batatas) and cassava (Manihot esculenta) (Kim et al 1994;Kwak et al 1995;You et al 1996;Lee et al 1999). Four POD cDNAs, three for anionic enzymes (swpa1, swpa2, swpa3) and one ( swpn1) encoding a neutral POD, were isolated and characterized from suspension cultures of sweetpotato (Huh et al 1997;Kim et al 1999).…”

Molecular cloning of a cytosolic ascorbate peroxidase cDNA from cell cultures of sweetpotato and its expression in response to stress

“…Plant cells in culture are considered to be subject to high levels of oxidative stress, suggesting that they are good models for the study of antioxidative mechanisms and the production of useful antioxidants. In previous studies, we have investigated the levels of antioxidant enzymes such as SODs and PODs, and lowmolecular-weight antioxidants such as ascorbate and glutathione in 100 cell lines derived from various plant species (Kim et al 1994;You et al 1996;Ahn et al 1999;Lee et al 1999a). Plant cells growing in culture were found to have much higher levels of antioxidant enzymes such as SODs and PODs than differentiated plant tissues.…”

Overexpression of alfalfa mitochondrial HSP23 in prokaryotic and eukaryotic model systems confers enhanced tolerance to salinity and arsenic stress

“…These include chloroplasts, mitochondria, the endoplasmic reticulum, and the cytosol (Vierling 1991). sHSPs are induced by various stress conditions including heat (Heckathorn et al 2002; Lee et al 1999; Prändl et al 1998 ) , chilling (Neta-Sharir et al 2005; Sabehat et al 1996; Soto et al 1999), toxic metals (Wollgiehn and Newmann 1995), and oxidative injury (Banzet Banzet et al 1998), as well as developmental stimuli. The correlation between sHSP synthesis and the stress response led to the hypothesis that sHSPs protect cells from the detrimental effects of stress.…”