The Study On Relation Of Rice NADP-ME4 Gene And Abiotic Stresses

NADP-malic enzyme is an oxidation decarboxylase existing widely in plants, animals, prokaryotic and eukaryotic microorganisms. It catalyzes the oxidative decarboxylation of L-malate to pyruvate, CO2 and NADPH in the presence of a bivalent cation （Mg2+ or Mn2+） to participate in different metabolic pathways. NADP-MEs exist in the form of isoenzymes encoded by small gene families and locate in plastid and cytosol in plant.This study had a research on NADP-ME4 （NCBI:NM₀01050754） gene of rice. NADP-ME4 had a degree of 79% and 90% with ANADP-ME1 and ZmcytME respectively, and a close genetic relationship with them in the evolutionary tree, AtNADP-ME1, ZmcytME were specifically expressed in the root, so we considered NADP-ME4 within the same branch may also be cytoplasmic non-photosynthetic gene, and have a close relationship with metabolic activity in the root. Observation of the transgenic Arabidopsis protoplast showed that NADP-ME4 was distributed in the cytosol.NADP-ME4 promoter contained TATA-box, CAAT-box, motif I, Skn-1_motif and other cis -acting elements related to environmental factors. qRT-PCR to detect GUS gene in NADP-ME4-pro-GUS gene transgenic Arabidopsis thaliana showed a low amount of expression in different tissues, while a bit higher about 0.1 times of the contrast in root, it probably indicted that NADP-ME4 gene was constitutively expressed at a low level in rice.After 12 hours treated with different concentrations of NaCl, PEG6000, and NaHCO3 stresses, the transcription of the NADP-ME4 gene increased in the roots of rice seedlings while decreased in the leaves, especially at 30mM NaHCO3 stress, the transcription increased to 3 times in roots.Three transgenic lines and wild-type Arabidopsis were grown at different concentrations of NaCl and Mannitol stresses for 14 days. The transgenic Arabidopsis over-expressing NADP-ME4 gene grew better than WT and had an enhanced tolerance to salt and drought stresses.No matter on the level of gene expression or the tolerance of transgenic plants, NADP-ME4 gene were able to response to a variety of abiotic stresses, the gene was involved in plant defense response reaction.