Identification and Expression Profiling of Nonphosphorus Glycerolipid Synthase Genes in Response to Abiotic Stresses in Dendrobium catenatum.

Xinqiao Zhan,Bizeng Mao,Yichun Qian

doi:10.3390/plants10061204

Xinqiao Zhan, Bizeng Mao + Show 1 more

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https://doi.org/10.3390/plants10061204

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Abstract

Dendrobium catenatum, a valuable Chinese herb, frequently experiences abiotic stresses, such as cold and drought, under natural conditions. Nonphosphorus glycerolipid synthase (NGLS) genes are closely linked to the homeostasis of membrane lipids under abiotic stress in plants. However, there is limited information on NGLS genes in D. catenatum. In this study, a total of eight DcaNGLS genes were identified from the D. catenatum genome; these included three monogalactosyldiacylglycerol synthase (DcaMGD1, 2, 3) genes, two digalactosyldiacylglycerol synthase (DcaDGD1, 2) genes, and three sulfoquinovosyldiacylglycerol synthase (DcaSQD1, 2.1, 2.2) genes. The gene structures and conserved motifs in the DcaNGLSs showed a high conservation during their evolution. Gene expression profiling showed that the DcaNGLSs were highly expressed in specific tissues and during rapid growth stages. Furthermore, most DcaNGLSs were strongly induced by freezing and post-freezing recovery. DcaMGD1 and DcaSQDs were greatly induced by salt stress in leaves, while DcaDGDs were primarily induced by salt stress in roots. Under drought stress, most DcaNGLSs were regulated by circadian rhythms, and DcaSQD2 was closely associated with drought recovery. Transcriptome analysis also revealed that MYB might be regulated by circadian rhythm and co-expressed with DcaNGLSs under drought stress. These results provide insight for the further functional investigation of NGLS and the regulation of nonphosphorus glycerolipid biosynthesis in Dendrobium.

Highlights

Plant cell membranes have specific, nonrandom glycerolipid compositions [1]
Under Pi starvation, phospholipids are degraded and nonphosphorus glycerolipids (NGLs) biosynthesis is usually activated in chloroplast membranes, but DGDG biosynthesis is found in extraplastidic membranes and depends on DGDG synthase (DGD1) [4,5]
As with DGDG biosynthesis, MGD1 is involved in the bulk of MGDG biosynthesis in chloroplasts, while MGD2 and MGD3 are strongly induced by Pi starvation and are responsible for an alternative galactolipid pathway in nongreen tissues such as roots and flowers [7]

Summary

Introduction

Plant cell membranes have specific, nonrandom glycerolipid compositions [1]. Chloroplasts mainly contain four glycerolipids, including high levels of the galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) and low levels of sulfoquinovosyldiacylglycerol (SQDG) and phosphatidylglycerol (PG) [2]. The thylakoids represent the largest membrane system in leaf mesophyll cells and contain approximately 52% MGDG, 26% DGDG, 6.5% SQDG, and 9.5% PG [2]. Nonphosphorus glycerolipids (NGLs) MGDG, DGDG, and SQDG play important roles in membrane lipid remodeling during the replacement of phospholipids [3]. Under Pi starvation, phospholipids are degraded and NGLs biosynthesis is usually activated in chloroplast membranes, but DGDG biosynthesis is found in extraplastidic membranes and depends on DGDG synthase (DGD1) [4,5]. As with DGDG biosynthesis, MGD1 is involved in the bulk of MGDG biosynthesis in chloroplasts, while MGD2 and MGD3 are strongly induced by Pi starvation and are responsible for an alternative galactolipid pathway in nongreen tissues such as roots and flowers [7]

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