Induced expression of the gene for NADP-malic enzyme in leaves of Aloe vera L. under salt stress

A cDNA fragment for NAbP-malic enzyme, catalyzing the reversible oxidative decarboxylation of L-malate to produce CO,, pyruvate and NADPH, was isolated from the leaves of a 2-month-old Aloe vera L., The level of expression of NADP-ME mRNA and accumulation of NADP-ME (AvME) protein under salt stress conditions were compared between a tolerant aloe, Aloe vera L. and a sensitive aloe, Aloe saponarea Haw. The results suggested that both the expression of the gene and the accumulation of the protein were induced in the two kinds of aloe, and the strength was related to the degree of salt tolerance. Northern blot analysis revealed that the gene for NADP-malic enzyme in Aloe vera L.(AvME) was induced by high salt, dehydration, and exogenous abscisic acid (ABA), but not by cold treatment. To further confirm whether the synthesis of AvME protein was induced with hours of treatment, Western blot analysis of the samples was conducted. The results indicated that the induction of AvME protein expression was obvious after 48 h at high salt and the level was increased with the hours of treatment.