Effect of salt stress on plants of wild-type Nicotiana tabacum L. and transformants with a choline oxidase (codA) gene

Abstract

Background. Soil salinity is one of the limiting factors for plant growth and productivity. The areas of saline lands increase annually, so it is important to study the mechanisms of plant resistance to salt stress.Material and methods. We studied the effect of salt stress on tobacco plants (Nicotiana tabacum L.) of the wild type (‘Samsun’) and the transgenic line Cod 38 obtained by introducing the сodA gene, encoding bacterial choline oxidase, from Arthrobacter globiformis. Salt tolerance of the compared genotypes was assessed according to the growth indicators and the ability to preserve the pool of photosynthetic pigments under model salt stress conditions (150 mМ NaCl). The sensitivity of plants to salt stress was analyzed using biochemical tests that reflected the intensity of peroxidation processes and the activity of antioxidant enzymes (superoxide dismutase, and peroxidase).Results. The survival rates and biometric characteristics of transformants under salt stress were significantly higher than in wild-type plants. Under the impact of salt stress, the content of chlorophylls and carotenoids in the leaves of ‘Samsun’ plants decreased 1.5 and 1.3 times, respectively. Contrastingly, transformants under the same conditions showed a tendency to increase the pool of plastid pigments. A peculiarity of transgenic plants was also the reduced malondialdehyde content in their leaves, which indicates a low intensity of lipid peroxidation during salinization and can be explained by the functioning of endogenous glycine betaine as a compound with a multifunctional effect.Conclusions. It was shown that the transformation of plants with the bacterial gene of choline oxidase, followed by the accumulation of the protein product of the codA gene – glycine betaine, even in a minimal amount, was accompanied by positive effects on tobacco plants under salt stress conditions.