Molecular Characterization of Mungbean Peroxisomal Alanine Glyoxylate Aminotransferase Gene Induced by Low Temperature Stress

Photorespiration reduces carbon fixation rate, but it is an essential process in plant. Photorespiration involves reactions in chloroplasts, peroxisomes, and mitochondria. In photorepiratory peroxisome, alanine glyoxylate aminotransferase (AGT) catalyzes the conversion of alanine and glyoxylate into glycine and pyruvate, respectively. We isolated a low temperature-inducible cDNA encoding AGT from mungbean leaves. The full-length cDNA, designated as MLT92, contains an open reading frame of 1,203 nucleotides coding for a protein of 401 amino acids. Genomic DNA blotting showed that the mungbean genome has one copy of MLT92. MLT92 mRNA was induced by low temperature and its RNA expression was not much increased by drought stress. ABA and NaCl did not induce RNA expression of MLT92. Based on GFP/RFP targeting experiment, GFP-MLT92 fusion protein and SKL-RFP, a peroxisome marker, were colocalized to peroxisome in tobacco protoplasts. This suggests that peroxisomal MLT92 is involved in molecular response to low temperature stress.