Cadmium stress induces changes in the lipid composition and biosynthesis in tomato (Lycopersicon esculentum Mill.) leaves

Abstract

The effects of cadmium (Cd) stress on lipid composition and biosynthesis were investigated in young leaves of ten-day-old tomato seedlings (Lycopersicon esculentum Mill. cv. Ibiza F1). Cd was found to be mainly accumulated in roots, but a severe inhibition of biomass production occurred in leaves, even at its low concentration (1.0 lM). Seven days after Cd treatment, the membrane lipids were extracted and separated on silica-gel thin layer chromatography (TLC). Fatty acid methyl esters were analyzed by FID-GC on a capillary column. Our results showed that Cd stress decreased the quantities of all lipids classes (phospholipids, galactolipids and neutral lipids). Likewise, there was also a decline in the levels of tri-unsaturated fatty acids, such as linolenic (C18:3) and hexadecatrienoic (C16:3) acids. The linolenic acid (C18:3) decreased in monogalactosyldiacylglycerol (MGDG) and all phospholipids, while hexadecatrienoinic acid (C16:3) declined mainly in MGDG. Moreover, Cd at high concentrations (25.0 and 50.0 lM) significantly enhanced the levels of lipid peroxides. Radiolabelling experiments were carried out by laying down microdroplets of [1-14 C]acetate-a major precursor of lipid biosynthesis-on attached leaves of the control and Cd-treated plants. After incubation for 1, 2, 12 and 24 h, the leaves were harvested and lipids extracted and analysed. Cd stress was found to decrease the incorporation of [1-14 C]acetate in total lipids. The biosynthesis of total lipids was altered with 25.0 and 50.0 lM Cd. The decline in the incorporation of [1-14 C]acetate due to Cd stress was observed in all lipid classes. There was also a substantial decline in the incorporation of [1-14 C]acetate in tri-unsaturated fatty acids. The results indicate that Cd treatment induces an oxidative stress by inhibiting the chloroplastic and extrachloroplastic lipid-biosynthesis pathways as well as lipid peroxidation.

Calcium application enhances growth and alleviates the damaging effects induced by Cd stress in sesame (Sesamum indicumL.)

“…Improved lipid synthesis can mediate and rectify ROS or hormone-regulated signaling (Wi et al 2014). Reduced phospholipid and unsaturated fatty acid biosynthesis due to Cd stress has also been reported in different plants (Ben Ammar et al 2007;Elloumi et al 2014;Sofo et al 2016). Calcium application mitigated the cadmium stress on phospholipids and neutral lipids, all of which play an important role in membrane functioning (Kuznetsova et al 2008;Abd_Allah et al 2015).…”

Membrane permeability and micro- and macroelement accumulation in spring wheat cultivars during the short-term effect of salinity- and PEG-induced water stress

“…It has been suggested that the high level of unsaturation of membrane lipids may be required to maintain the degree of fluidity needed for diffusion of lipophilic compounds and may confer a suitable geometry to the lipid molecules (Guerfel et al 2008). However, a decrease in unsaturation in response to metal stress has also been reported (Ben Ammar et al 2007;Filek et al 2010). The increase in plasmalemma unsaturation in less tolerant plants under NaCl treatment may indicate an increase in the fluidity of the membrane surface, which could facilitate the deep penetration of toxic active oxygen species into the cell membranes where receptive fatty acid double bonds are located (Guerfel et al 2008).…”

Characterisation of the wheat phospholipid fraction in the presence of nickel and/or selenium

“…Further quantitative analysis (Table 3) of the major PLs for both organs revealed that the total amount of phospholipids was the lowest in the shoots of wheat seedlings treated with Ni both used individually and in combination with Se. Also, significant decreases in the content of phospholipid classes were reported in cadmium stressed tomato (Ouariti et al 1997;Ben Ammar et al 2007). Figure 1 shows the composition of PLs for wheat seedlings in Ni and/or Se presence.…”