Fatty acid composition and activity of the mitochondrial respiratory chain complex I of pea seedlings under water deficit

Abstract

In this work the effect of insufficient watering and plant growth regulator melaphen (melamine salt of bis(oxymethyl)phosphonic acid) on the fatty acid composition and the energy of 5-day etiolated pea seedling mitochondria (Pisum sativum) were studied.Isolation of mitochondria from 5-day sprouts epicotyls was performed by differential centrifugation. The rate of mitochondria respiration was measured with the aid of Clarke oxygen electrodes and LP-7 polarograph (Czech Republic). Fatty acid methyl esters (FAMEs) were produced by acidic methanolysis of mitochondrial membrane lipids and FAMEs quantification was performed using a Kristall 2000M chromatograph (Russia) with flame-ionization detector and quarts capillary column SPB-1 (50 m × 0.32 mm, a nonpolar phase layer – 0.25 μm). It has been shown that insufficient watering results in alteration of fatty acid composition in mitochondrial membranes of seedlings. The ratio of the content of С18 – unsaturated fatty acids to the stearic acid content decreases by 1.5 times. Significant changes are observed in the content of fatty acids with 20 carbon atoms: the ratio of unsaturated fatty acids to saturated fatty acids decreases by 3.3 times. The changes in fatty acid composition of mitochondrial membranes are in correlation with changes in maximum rates of NAD-dependent substrates oxidation (the Pearson’s coefficient of correlation for С18 fatty acids is 0.7651, for С20 fatty acids – 0.963).