Abstract
Low temperature is one of the major abiotic stresses that restrict the growth and development of maize seedlings. Membrane lipid metabolism and remodeling are key strategies for plants to cope with temperature stresses. In this study, an integrated lipidomic and transcriptomic analysis was performed to explore the metabolic changes of membrane lipids in the roots of maize seedlings under cold stress (5°C). The results revealed that major extraplastidic phospholipids [phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidic acid (PA), and phosphatidylinositol (PI)] were dominant membrane lipids in maize root tissues, accounting for more than 70% of the total lipids. In the transcriptome data of maize roots under cold stress, a total of 189 lipid-related differentially expressed genes (DEGs) were annotated and classified into various lipid metabolism pathways, and most of the DEGs were enriched in the “Eukaryotic phospholipid synthesis” (12%), “Fatty acid elongation” (12%), and “Phospholipid signaling” (13%) pathways. Under low temperature stress, the molar percentage of the most abundant phospholipid PC decreased around 10%. The significantly up-regulated expression of genes encoding phospholipase [phospholipase D (PLD)] and phosphatase PAP/LPP genes implied that PC turnover was triggered by cold stress mainly via the PLD pathway. Consequently, as the central product of PC turnover, the level of PA increased drastically (63.2%) compared with the control. The gene-metabolite network and co-expression network were constructed with the prominent lipid-related DEGs to illustrate the modular regulation of metabolic changes of membrane lipids. This study will help to explicate membrane lipid remodeling and the molecular regulation mechanism in field crops encountering low temperature stress.
Highlights
Maize (Zea mays L.), originated from subtropical zones, is a typical thermophilic crop that requires a relatively high growth temperature, especially in the seedling and vegetative growth stage (Rodríguez et al, 2014)
The level of lyso-phospholipids altered to varying degrees, and the content of LPG increased more than 1.5 times in comparison with the control
Membrane lipid metabolism and remodeling are key strategies for plants to cope with temperature stresses (Moellering et al, 2010; Li et al, 2016)
Summary
Maize (Zea mays L.), originated from subtropical zones, is a typical thermophilic crop that requires a relatively high growth temperature, especially in the seedling and vegetative growth stage (Rodríguez et al, 2014). In northeastern China (around 44◦ north latitude), low temperatures in early spring and sudden temperature drops in late spring seriously affects the growth and development of maize seedlings. Understanding the response of plants to low temperature stress at the molecular level is of great importance in developing cold-resistance crops. The plant membrane is the first barrier to cope with external environmental stimuli, which could be attributed to its typical fluidity and certain protective properties (Chinnusamy et al, 2007). Low temperature stress increased the unsaturation of fatty acids, which increased the fluidity of the plant membrane, reduced the tendency of non-bilayer phase formation, and enhanced the integrity and function of the plant membrane (Uemura and Steponkus, 1997; Hou et al, 2016)
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