Abstract
Superoxide dismutase is an important antioxidant enzyme extensively existing in eukaryote, which scavenges reactive oxygen species (ROS) and plays an essential role in stress tolerance of higher plants. A full-length cDNA encoding Cu/Zn SOD was cloned from leaves of Gynura bicolor DC. by rapid amplification of cDNA ends (RACE). The full-length cDNA of Cu/Zn SOD is 924 bp and has a 681 bp open reading frame encoding 227 amino acids. Bioinformatics analysis revealed that belonged to the plant SOD super family. Cu/Zn SODs of the Helianthus annuus, Mikania micrantha, and Solidago canadensis var. scabra all have 86% similarity to the G. bicolor Cu/Zn SOD. Analysis of the expression of Cu/Zn SOD under different treatments revealed that Cu/Zn SOD was a stress-responsive gene, especially to 1-MCP. It indicates that the Cu/Zn SOD gene would be an important gene in the resistance to stresses and will be helpful in providing evidence for future research on underlying molecular mechanism and choosing proper postharvest treatments for G. bicolor.
Highlights
Reactive oxygen species (ROS) is a group of substances which have oxidation properties to obtain electron from adjacent materials
(2) Being stored in low temperature: (d) control group (CKL): without any treatment; (e) controlled atmosphere treatment (CA): leaves were placed in normal polyethylene plastic bags with a controlled atmosphere of 3% O2 and 97% N2; the gas compositions were continuously controlled constant throughout the storage; (f) hypobaric treatment (HT): leaves were put in a plastic basket and placed into a hypobaric chamber, whose pressure was 61.33 kPa
The alignment analysis by Blast search in NCBI database revealed that G. bicolor Cu/Zn superoxide dismutase (SOD) shared high homology with many other Cu/Zn SODs, such as Helianthus annuus Cu/Zn SOD (CAH06454.1), Mikania micrantha Cu/Zn SOD (ACZ51444.1), and Solidago canadensis var. scabra Cu/Zn SOD (O04996.3) have 86% identity to G. bicolor Cu/Zn SOD, which hints the high conservation of Cu/Zn SODs during the long period of evolution
Summary
Reactive oxygen species (ROS) is a group of substances which have oxidation properties to obtain electron from adjacent materials. ROS is classified into two groups in botanical system: inorganic radical, including hydrogen peroxide (H2O2) and singlet oxygen (1O2), and organic radical, which mainly are the products of membrane lipid peroxidation. The ROS level will be enhanced when plant is exposed to biotic and abiotic stresses, which result in the inactivation of enzymes and breakage of DNA strands and membrane lipids [2, 3]. A whole set of mechanisms have been evolved in plant cells to cope with environment stress, scavenge overmuch ROS in time, and adjust internal environment. Scavenging mechanisms include enzymatic and nonenzymatic systems. The former mainly include superoxide dismutase (SOD), ascorbate peroxidase (APX), catalyse (CAT), and glutathione peroxidase (GPX)
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