Overexpression of glycerol-3-phosphate acyltransferase gene improves chilling tolerance in tomato

Abstract

A tomato (Lycopersicon esculentum Mill.) glycerol-3-phosphate acyltransferase gene (LeGPAT) was isolated. The deduced amino acid sequence revealed that LeGPAT contained four acyltransferase domains, showing high identities with GPAT in other plant species. A GFP fusion protein of LeGPAT was targeted to chloroplast in cowpea mesophyll protoplast. RNA gel blot showed that the mRNA accumulation of LeGPAT in the wild type (WT) was induced by chilling temperature. Higher expression levels were observed when tomato leaves were exposed to 4 degrees C for 4 h. RNA gel and western blot analysis confirmed that the sense gene LeGPAT was transferred into the tomato genome and overexpressed under the control of 35S-CaMV. Although tomato is classified as a chilling-sensitive plant, LeGPAT exhibited selectivity to 18:1 over 16:0. Overexpression of LeGPAT increased total activity of LeGPAT and cis-unsaturated fatty acids in PG in thylakoid membrane. Chilling treatment induced less ion leakage from the transgenic plants than from the WT. The photosynthetic rate and the maximal photochemical efficiency of PS II (Fv/Fm) in transgenic plants decreased more slowly during chilling stress and recovered faster than in WT under optimal conditions. The oxidizable P700 in both WT and transgenic plants decreased obviously at chilling temperature under low irradiance, but the oxidizable P700 recovered faster in transgenic plants than in the WT. These results indicate that overexpression of LeGPAT increased the levels of PG cis-unsaturated fatty acids in thylakoid membrane, which was beneficial for the recovery of chilling-induced PS I photoinhibition in tomato.

Cloning, heterologous expression and biochemical characterization of plastidial sn-glycerol-3-phosphate acyltransferase from Helianthus annuus

“…Moreover, differences in the degree of unsaturation of 16 carbon atoms molecules were detected between the two positions of the PG molecule. A similar finding was reported previously in tomato (Sui et al, 2007), where 16:0 desaturation occurs asymmetrically between positions sn-1 and -2, enriching the sn-1 position in saturated fatty acids and the sn-2 in delta 3-trans-hexadecenoyl (16:1(3t)).…”

Responses of Unsaturated Fatty Acid in Membrane Lipid and Antioxidant Enzymes to Chilling Stress in Sweet Sorghum (Sorghum bicolor (L.) Moench) Seedling

“…Zhang et al (2005) reported that modulated fatty acid desaturation via over expression of two distinct ω-3 desaturases differentially alters tolerance to various abiotic stresses in transgenic tobacco cells and whole plants. The different substrate selectivity of GPAT enzyme can also affect the cold resistance of plants (Sui et al, 2007). Introduction of the GPAT gene into rice increased the unsaturated fatty acid levels and led to cold resistance (Ariizumi et al, 2002).…”

“…Some reports suggested that the changes in the content of unsaturated fatty acids can improve plant tolerance to environmental stresses such as cold, heat and drought (Dakhma et al, 1995;Liu et al, 2008;Matos et al, 2002;Sui et al, 2007). Under chilling stress, lipids in cell membranes change from a lipid-crystalline condition to a solid state at a critical temperature that is determined by the ratio of saturated to unsaturated fatty acids (Quinn, 1988).…”

“…Tolerance to chilling stress is closely connected with the unsaturated fatty acid content of plant membrane lipids (Cheng et al, 2014;Szalontai et al, 2003). Previous evidences have reported that over expression of unsaturated fatty acids gene improves chilling tolerance in tomato (Sui et al, 2007). Also, over expression of tomato chloroplast omega-3 fatty acid desaturase gene alleviates the photoinhibition of photosystems II and I under chilling stress (Liu et al, 2008).…”

Overexpression of the Arabidopsis 10-Kilodalton Acyl-Coenzyme A-Binding Protein ACBP6 Enhances Freezing Tolerance

“…Furthermore, tolerance at 1°C for 11 d was conferred using a gene encoding a nonspecific cyanobacterial desaturase, and the resultant transgenic tobacco plants showed a reduction in saturated fatty acid content in membrane lipids (Ishizaki-Nishizawa et al, 1996). The overexpression of glycerol-3-phosphate acyltransferase altered the unsaturation of fatty acids and conferred chilling tolerance in transgenic plants (Ariizumi et al, 2002;Sakamoto et al, 2003;Sui et al, 2007). Hence, modifications in lipid composition that stabilize cell membranes and prevent cellular leakage lead to cold tolerance.…”