Biochemical and Transcriptional Regulation of Membrane Lipid Metabolism in Maize Leaves under Low Temperature

Abstract

Membrane lipid modulation is one of the major strategies plants have developed for cold acclimation. In this study, a combined lipidomic and transcriptomic analysis was conducted, and the changes in glycerolipids contents and species, and transcriptional regulation of lipid metabolism in maize leaves under low temperature treatment (5°C) were investigated. The lipidomic analysis showed an increase in the phospholipid phosphatidic acid (PA) and a decrease in phosphatidylcholine (PC). And an increase in digalactosyldiacylglycerol and a decrease in monogalactosyldiacylglycerol of the galactolipid class. The results implied an enhanced turnover of PC to PA to serve as precursors for galactolipid synthesis under following low temperature treatment. The analysis of changes in abundance of various lipid molecular species suggested major alterations of different pathways of plastidic lipids synthesis in maize under cold treatment. The synchronous transcriptomic analysis revealed that genes involved in phospholipid and galactolipid synthesis pathways were significantly up-regulated, and a comprehensive gene-metabolite network was generated illustrating activated membrane lipids adjustment in maize leaves following cold treatment. This study will help to understand the regulation of glycerolipids metabolism at both biochemical and molecular biological levels in 18:3 plants and to decipher the roles played by lipid remodeling in cold response in major field crop maize.

Effects of Chilling on the Structure, Function and Development of Chloroplasts

“…As mentioned above, the presence of high levels of unsaturated FAs in chloroplasts increases the tolerance of plants to chilling ( Cronan and Roughan, 1987 ; Murata et al, 1992 ). Furthermore, upon exposure to chilling, total FAs are increased, phospholipids are preferentially synthesized and the unsaturation degree of DGDG increases in some plants ( Saczynska et al, 1993 ; Partelli et al, 2011 ; Scotti-Campos et al, 2014 ; Gu et al, 2017 ). Lipids have selective distributions in subcellular organelles, membrane leaflets and membrane domains.…”

Characterisation of genes involved in galactolipids and sulfolipids metabolism in maize and Arabidopsis and their differential responses to phosphate deficiency

“…In plants, the synthesis of galactolipids MGDG and DGDG involves two different pathways: the plastid/chloroplast localised prokaryotic pathway and the endoplasmic reticulum compartmentalised eukaryotic pathway (Ohlrogge et al 1991). In Arabidopsis, a typical 16:3 plant, the galactolipids synthesis relies on both eukaryotic pathway and prokaryotic pathway, whereas the 18:3 plant maize has been shown to mainly use the eukaryotic pathway for galactolipids synthesis (Li et al 2016a;Gu et al 2017). Since most of the previous studies on the galactolipids metabolism under phosphorous deficiency conditions have focussed on the 16:3 plant Arabidopsis, the information on the 18:3 plants has been lacking.…”

“…For expression analysis of maize MGD, DGD and SQD genes under abiotic stresses, the publicly available maize RNA-seq transcriptome datasets deposited in the NCBI SRA database were used. The transcriptome data includes cold (SRX2672484) (Gu et al 2017), heat (SRR1238715, SRR1819196 and SRR1819198), salt (SRR1238719) and UV (SRR1238720) ( Table S2) (Makarevitch et al 2015). For cold stress, seeds of maize (He 344) were grown at 22 C and 16 h/8 h (light/dark) daily photoperiodic cycle.…”

“…The 2-week-old seedlings were removed to another growth chamber set at 5 C for cold treatment (other conditions remained the same), and the seedlings grown at 22 C were used as controls. Samples of maize leaf were collected at 3-day time point under cold treatment (Gu et al 2017). Heat, salt and UV stresses were applied to maize variety B73: maize seeds were grown at 24 C in 1 : 1 mix of autoclaved field soil and MetroMix, and the light conditions under all conditions are natural light conditions For heat stress, seedlings were placed at 50 C for 4 h. For high salt stress, plants were watered with 300 mmol NaCl 20 h before collecting.…”

“…In plant cells, the synthesis of glycerolipids could be processed via plastid/chloroplast compartmentalised prokaryotic pathway, and endoplasmic reticulum localised eukaryotic pathway respectively (Ohlrogge et al 1991). Some plants, such as Arabidopsis, whose major chloroplast lipids (MGDG and DGDG) are generated jointly by both pathways, are typically characterised by the high levels of 16:3 fatty acids, are termed 16:3 plants (Heinz and Rougham 1983;Dörmann et al 1995), whereas the others, such as maize, whose MGDG and DGDG synthesis relies almost entirely on the ER pathway, have products with high levels of 18:3 fatty acids, so they are called 18:3 plants (Wada and Murata 2010;Gu et al 2017). Previous studies on the metabolism and function of galactolipids have focussed mainly on the 16:3 plant Arabidopsis, but only few studies have been conducted on 18:3 plant species (Chen and Thelen 2013;Gu et al 2017).…”