Resistance of genetically modified wheat plants, containing a double-stranded RNA suppressor of the

Abstract

Aim. Analysis of physiological and biochemical characteristics and grain productivity traits of transgenic common wheat plants (Triticum aestivum L.) with a double-stranded RNA suppressor of the proline dehydrogenase gene (pdh) compared to non-transgenic genotypes under conditions of soil drought. Methods. Biochemical assays: spectrophotometric measurements of antioxidant enzymes (SOD, APX) activity, proline dehydrogenase activity and free L-proline content; biotechnological assays: Agrobacterium-mediated transformation in planta; physiological: morphometric traits and elements of grain productivity; mathematical statistics. Results. The presence of a double-stranded RNA suppressor of the gene pdh in transgenic plants leads not only to a decrease in enzyme activity (on average 2 times compared to the nontransgenic plants), but also to an increase in the content of free L-proline both under optimal conditions and under soil drought (2.6–4.1 times). Under soil moisture defi ciency, transgenic plants with reduced pdh gene activity in terms of yield structure signifi cantly exceeded the corresponding values of grain productivity elements for the non-transformed ones. In terms of the grain weight from the main stem, the biotechnological plants under soil moisture defi ciency exceeded the control plants 1.5–1.6 times, while the number of grains did not differ signifi cantly. The grain productivity of the whole plant in the transformed lines under conditions of soil moisture defi ciency was somewhat inferior to those in the nontransformed plants grown under optimal conditions. Soil drought caused a signifi cant increase in SOD and APX activity (by 40 and 11 %, respectively) in plants of the original variety. On the contrary, the activity of both antioxidant enzymes under drought conditions in transgenic plants decreased: SOD – down to 73–76 %, APX – down to 82–86 %, compared with the variant of 70 % of fi eld capacity. Conclusions. The analysis of physiological and biochemical characteristics, as well as economic and grain productivity elements of transgenic common wheat plants with a double-stranded RNA suppressor of the proline dehydrogenase gene showed their increased tolerance to soil drought, compared with non-transgenic genotypes, which may be associated with higher proline accumulation and an increase in the antioxidant enzymes activity. Under soil moisture defi ciency, transgenic wheat plants with reduced pdh gene activity signifi cantly exceeded the corresponding values of grain productivity elements for non-transformed plants. The analysis of the antioxidant enzymes activity in the chloroplasts of transgenic plants showed that under physiological conditions, the antioxidant system works more actively in comparison with non-transgenic genotypes, which may be a prerequisite for increasing the tolerance of these plants to the infl uence of stressors of various origin. It is likely that the positive relationship between the level of free L-proline and the resistance of transgenic wheat plants to osmotic stress is associated either with the effect of L-proline on the expression of other genes of the stress-strain response of plants, or with the positive effect of the increased content of this amino acid on resistance at the early stages of stress development. It has been suggested that an increase in the antioxidant enzymes activity in biotechnological plants can be caused by the expression of heterologous genes.