BIOCHEMICAL RESPONSES IN AGROBACTERIUM-INFECTED OILSEED RAPE EXPLANTS DURING EARLY STAGES OF REGENERATION IN THE PRESENCE OF DITHIOTHREITOL

Abstract

We investigated the impact of exogenous dithiothreitol on the activities of enzymatic antioxidants ascorbate peroxidase and catalase, and the levels of non-enzymatic antioxidants and osmoprotectant proline, and total soluble sugars in Agrobacterium-infected and non-infected (control) explants of oilseed rape (Brassica napus L.) after the 3rd and 17th day of in vitro culture. This investigation was conducted with or without dithiothreitol at a concentration of 1 mg/L. Dithiothreitol is a sulphur-containing compound that act as a reducing agent, impacting the redox environment within plant cells. Explants were obtained from six-day-old hypocotyls of the cultivars Ability and Lancia, and infected with Agrobacterium tumefaciens GV3101 carrying the binary vector. The application of dithiothreitol into co-cultivation and regeneration media led to a significant decrease in the activities of ascorbate peroxidase and catalase in both infected and non-infected explants of both cultivars. In contrast, explants regenerated without dithiothreitol exhibited a significant increase in ascorbate peroxidase activity and a decrease in catalase activity, although the decrease in catalase activity was not as pronounced. The proline content increased significantly in all analysed explants, with the highest increase observed in explants regenerated in the presence of dithiothreitol. This suggests that dithiothreitol might indirectly contribute to the reduced formation of reactive oxygen species, which is generally negatively correlated with transformation efficiency.