Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 15, 2009
Publication Date: July 5, 2009
Citation: Chen, X. Brenneman, T. Culbreath, A. Holbrook, JR. C.C. Guo, B. 2009. Identification of two peanut germin-like genes and the potential superoxide dismutase activity. American Peanut Research and Education Society Abstracts. Presented at the APRES annual meeting, July 14-17, 2009 in Raleigh, N.C. Technical Abstract: Germin and germin-like protein (GLP) genes are members of large multigene families. These genes have been reported to play a role directly or indirectly in plant defense response. A number of GLPs have been demonstrated to have superoxidase dismutase (SOD) or oxalate oxidase (OxO) activity, leading to production of hydrogen peroxide. Two peanut germin-like genes, AhGERLand AhGERS, were identified from cDNA libraries. The AhGERL including 991 bp cDNA sequences encodes a 219 amino acid protein with a 21-residue signal peptide. After cleavage of the signal peptide, it has a mass of 20.84 kDa. The AhGERS of 744 bp cDNA encodes a protein with 220 amino acid residues containing a putative signal peptide of 24 residues, with a mass of 20.63 kDa after removal of the signal peptide. The two proteins both contain three motifs, Q/NDL/FCVAD, G(X)5HXH(X) 11G and G(X)5P(X) 4H(X) 3N, which are characteristics to germin-like proteins. Southern blot analysis showed that the two genes have at least four copies in the genome. Northern blots conducted with total RNA from leaves, seeds and roots tissues indicated that AhGERL is mainly expressed in peanut leaves. Enzyme assay indicated that the coding sequence of AhGERL exhibited superoxide dismutase activity but no detectable oxalate oxidase activity, while neither activity was detected for AhGERS. The SOD activity of AhGERL was less sensitive to hydrogen peroxide than SOD from horseradish, suggesting it to be copper/zinc-containing SOD (Cu/ZnSOD). The pET-AhGERL tranformed E.coli exhibited higher SOD activity and tolerance to paraquat-mediated growth inhibiton compared to empty vector (pET-28a) transformed cells, indicating that AhGERL conferred resistance to oxidative stress. The AhGERS and the enzymatic activity will be studied further.