Gene Expression Characteristics Of Rice (Oryza Sativa L.) Malic Enzyme (NADP-ME3)

NADP-malic enzyme （NADP-ME） is an oxidation decarboxylase existing widely in animals,plants and prokaryotes.It can catalytic malic acid oxidative decarboxylation to produce Pyruvic acid,CO2and reducing substances of NADPH under the divalent metal ion （Mg2+or Mn2+）, and NADP-ME plays an important role in plant metabolic and developmental processes,such as maintaining the osmotic potential of plant cells, the stability of cytoplasmic pH and to keeping balance of roots absorb the ion, so it is the one of the most important enzymes in organism life activities. Encoding rice（Oryza sativa L.） NADP-ME is a multi-gene family, studies show that the family consists of three cytoplasmic NADP-ME and one plastidic NADP-ME, and this study focuses on the expression characteristics of one of the cytoplasmic members （named as NADP-ME3）（GeneBank NM₀01061367）. Former we cloned the cDNA fragment of the gene, analysis and forecast its sequence with bioinformatics and it shows that NADP-ME ORF is1712bp encoding570amino acids, the molecular weight of62.9kD, then we connected it with GFP reporter gene to study the gene cellular localization.and we find the gene located in the cytoplasm, belonging to cytoplasmic NADP-ME gene family found in the transgenic Arabidopsis. To confirm the organization expression specificity of the NADP-ME3gene, we cloned the promoter region of NADP-ME3gene5’upstream to connect the GUS reporter gene construct ME3-pro-GUS expression vector, then transformed it into Arabidopsis thaliana,and detect the GUS gene expression in the primary veins of the transgenic Arabidopsis. To further understand the gene expression under abiotic stress of NaCl, NaHCO3, and PEG, we test it through the quantitative PCR.Our results show that, under NaCl stress, NADP-ME3gene expression decreased slightly in the roots and increased in the leaf expression. Under drought conditions with increasing concentration of PEG, the mRNA expression of NADP-ME3leaves is relatively higher, while the expression in roots is continued very low.In the alkaline environment conditions, the expression of NADP-ME3is relatively lower all the time. The results show that the NADP-ME3is able to respond to a variety of abiotic stresses and may be associated with the abiotic stress response of plants.To detect the role of NADP-ME3gene in the plant response to abiotic stress conditions, we observed the phenotype of overexpression NADP-ME3transgenic Arabidopsis thaliana and found that NADP-ME3can improve the power of salt tolerance.