Drought stress affects chloroplast lipid metabolism in rape (Brassica napus) leaves

Abstract

Rape (Brassica napus L. var. Bienvenue) is a 16:3 plant which contains predominantly prokaryotic species of monogalactosyldiacylglycerol i.e. sn-1 C18, sn-2 C16 (C18/C16 MGDG). Rape plants were exposed to a restricted water supply for 12 days. Under drought conditions, considerable changes in lipid metabolism were observed. Drought stress provoked a decline in leaf polar lipids, which is mainly due to a decrease in MGDG content. Determination of molecular species in phosphatidylcholine (PC) and MGDG indicated that the prokaryotic molecular species of MGDG (C18/C16) decreased after drought stress while the eukaryotic molecular species (C18/C18) remained stable. Drought stress had different effects on two key enzymes of PC and MGDG synthesis. The in vitro activity of MGDG synthase (EC. 2.4.1.46) was reduced in drought stressed plants whereas cholinephosphotransferase (EC. 2.7.8.2) activity was not affected. Altogether these results suggest that the prokaryotic pathway leading to MGDG synthesis was strongly affected by drought stress while the eukaryotic pathway was not. It was also observed that the molecular species of leaf PC became more saturated in drought stressed plants. This could be due to a specific decrease in oleate desaturase activity.

Cloning of a putative monogalactosyldiacylglycerol synthase gene from rice (Oryza sativa L.) plants and its expression in response to submergence and other stresses

“…6 A proposed model of the relationship between glycolysis and MGDG synthesis (refer to Shen and Wang 1991;Kelly and Dormann 2002;Ichihara 2001). Gal Galactose, Gal-1-P galactose-1-phosphate, Glu-1-P glucosel-1-phosphate, UDP uridine diphosphate, TCA cycle tricarboxylic acid cycle, ACP acyl carrier protein, G-3-P glycerol-3-phosphate, LPA lysophosphatidic acid, PA phosphatidic acid, DG 1,2-diacyl-sn-glycerol, DGD2 an Arabidopsis gene encoding a UDP-galactose-dependent digalactosyldiacylglycerol synthase, 16:0 length of carbon chain: number of double bonds in rape (Brassica napus) was reduced (Benhassaine-Kesri et al 2002). These results seem to contradict our data that OsMGD mRNA is increased by drought and salt treatment.…”

Photosynthetic Recovery of a Perennial GrassLeymus chinensisafter Different Periods of Soil Drought

“…This experiment showed that rewatering increased PSII capacity. Severe soil drought resulted in cell-membrane damage (Benhassaine-Kesri et al, 2002), and a decrease in leaf photosynthetic capacity (García and Lamattina, 2001;Xu and Zhou, 2006b). However, rewatering after long-term drought may repair the damage and stimulate the well photosynthesis.…”

Overexpression of the phosphatidylinositol synthase gene from Zea mays in tobacco plants alters the membrane lipids composition and improves drought stress tolerance

“…This membrane restructuring is thought to arise from the necessity of maintaining membrane order or fluidity (Benhassaine-Kesri et al 2002). Changes in the contents of leaf lipids that are induced by water deficiency depend on the plant's sensitivity or tolerance to drought.…”