Abstract
Plant production is limited in acid soils. The main constraint to plant growth on acid soils is the aluminum. The Al ions not only are toxic to root growth but also lead to phosphate deficiency. Certain plant species showing tolerance to these stresses release large amounts of organic acids, especially citric acid, from their roots. Genetic manipulation may be an approach to introduce such traits into plants. In the present study, we generated transgenic Arabidopsis thaliana with repressed cytosolic NADP-isocitrate dehydrogenase (NADP-ICDH) gene involved in citrate catabolism by RNAi technique. NADP-ICDH activities of transformants were repressed to approximately 10% of wild-type plants. These transformants increased citrate content and released 2.5-fold more citrate at the maximum compared to wild-type plants. In addition, transformants showed improved growth on acid soils. These results suggest that repression of NADP-ICDH expression is a useful strategy to enhance the ability of acid soil tolerance of plants.
