Molecular Analysis of a Copper- and Zinc-Containing Superoxide Dismutase Gene Isolated From the Latex of Euphorbia Characias: Another Piece in the Molecular Puzzle of Euphorbiaceae Latex Proteins

A copperand zinc-containing superoxide dismutase (Cu/Zn-SOD) cDNA was isolated from the Euphorbia characias latex (Elx) using consensus degenerate hybrid oligonucleotide primer (CODEHOP) design and RT-PCR strategy. Both 3’and 5’untraslated regions (UTR) were isolated by rapid amplification of cDNA ends (RACE) method. Analysis of the nucleotide sequence revealed that the Cu/Zn-SOD cDNA contains an open reading frame encoding a protein of 152 amino acids. Bioinformatic analyses of Elx SOD gene revealed a high identity rate with a large number of plant Cu/Zn-SODs in the deduced amino acid sequence. Since isoenzymes may be generated through the multiplicity of SOD genes or result from post-trascriptional events, genomic Southern blot in conjunction with northern blot experiments were also performed. The genomic analysis showed that the E. characias genome contains a single SOD gene. Northern blot analyses confirmed the presence of a single SOD mRNA demonstrating that alternative splicing does not occur. Quantitative real time-PCR (qRT-PCR) experiments showed that SOD gene expression in latex reaches maximum levels during the summer. These results suggest that the Cu/Zn-SOD of Euphorbia characias latex probably may be involved in the antioxidative process triggered by oxidative stress induced by the conditions of environmental change in which the plant lives.