Functional cjnditions of mitochondria determines the stability of pea seedlings to the insufficient watering
ul. Kosygin 4, Moscow, 119334, Russia,Emanuel Institute of Biochemical Physics of Russian Academy of Sciences1 pp. (accepted)
Displacements antioxidant - prooxidant balance in the direction of increasing the generation of reactive oxygen species (ROS) by mitochondria leads to oxidative stress. This displacement takes place under the influence of stress factors and underlies damage plant organisms (growth processes, crop capacity etc). Water deficiency reduces the functional activity as chloroplasts and mitochondria (AG Shugaev et al, 2007). As known, regulators of plant growth and development improve their tolerance to biotic and abiotic stresses, to water deficit in particular. Such growth regulators are melaphen - a melamine salt of bis(oxymetyl)phosphonic acid and its pyrimidine analog pyraphen (salt of bis (hydroxymethyl) phosphinic acid, 2,4,6-triaminopyrimidine. The aim of this work is to study the effect of insufficient watering and treatment of pea seeds with 2 × 10-12 M melaphen or 10-13M pyraphen on bioenergetic functions of 6-day etiolated pea seedling mitochondria. Water deficit led to decrease in the total content of С18 unsaturated fatty acids relative to the content of stearic acid about to 1.5 times. The ratio of unsaturated fatty acids containing 20 carbon atoms to a saturated decreased 3.3 times. Changing the fatty acid composition of mitochondrial membranes were accompanied by 30% reduction in the maximum rates of oxidation of NAD-dependent substrates and a decrease in the efficiency of oxidative phosphorylation.
The treatment of seeds with a 2×10-12 M melaphen solution before germination has prevented changes in the fatty acid composition of the membranes of seedlings, caused by water deficit and has prevented the alteration of the bioenergetic characteristics of mitochondria. At the same time pyraphen hardly exerts a protective action on the content of unsaturated C18 fatty acids, but prevents changes in the content of unsaturated C20 fatty acids. Seed treatment with pyraphen almost had no effect on the maximum rate of oxidation of NAD-dependent substrates by mitochondria seedlings in conditions low moisture, but the efficiency of oxidative phosphorylation was increased by 15%.
Discusses the role of C18 and C20 unsaturated fatty acids in the prevention of disruption of the complex I mitochondrial respiratory chain of pea seedlings under low moisture.