Diacylglycerol kinase (DGK) is an enzyme that plays a pivotal role in abiotic and biotic stress responses in plants by transforming the diacylglycerol into phosphatidic acid. However, there is no report on the characterization of soybean DGK genes in spite of the availability of the soybean genome sequence. In this study, we performed genome-wide analysis and expression profiling of the DGK gene family in the soybean genome. We identified 12 DGK genes (namely GmDGK1-12) which all contained conserved catalytic domains with protein lengths and molecular weights ranging from 436 to 727 amino acids (aa) and 48.62 to 80.93 kDa, respectively. Phylogenetic analyses grouped GmDGK genes into three clusters—cluster I, cluster II, and cluster III—which had three, four, and five genes, respectively. The qRT-PCR analysis revealed significant GmDGK gene expression levels in both leaves and roots coping with polyethylene glycol (PEG), salt, alkali, and salt/alkali treatments. This work provides the first characterization of the DGK gene family in soybean and suggests their importance in soybean response to abiotic stress. These results can serve as a guide for future studies on the understanding and functional characterization of this gene family.

Salinity is one of the most serious factors limiting the productivity of agricultural crops, with adverse effects on germination, plant vigor, and crop yield. This salinity may be natural or induced by agricultural activities such as irrigation or the use of certain types of fertilizer. The most detrimental effect of salinity stress is the accumulation of Na+ and Cl− ions in tissues of plants exposed to soils with high NaCl concentrations. The entry of both Na+ and Cl− into the cells causes severe ion imbalance, and excess uptake might cause significant physiological disorder(s). High Na+ concentration inhibits the uptake of K+, which is an element for plant growth and development that results in lower productivity and may even lead to death. The genetic analyses revealed K+ and Na+ transport systems such as SOS1, which belong to the CBL gene family and play a key role in the transport of Na+ from the roots to the aerial parts in the Arabidopsis plant. In this review, we mainly discuss the roles of alkaline cations K+ and Na+, Ion homeostasis-transport determinants, and their regulation. Moreover, we tried to give a synthetic overview of soil salinity, its effects on plants, and tolerance mechanisms to withstand stress.

Background Drought conditions adversely affect soybean growth, resulting in severe yield losses worldwide. Increasing experimental evidence indicates miRNAs are important post-transcriptional regulators of gene expression. However, the drought-responsive molecular mechanism underlying miRNA–mRNA interactions remains largely uncharacterized in soybean. Meanwhile, the miRNA-regulated drought response pathways based on multi-omics approaches remain elusive. Results We combined sRNA, transcriptome and degradome sequencing to elucidate the complex regulatory mechanism mediating soybean drought resistance. One-thousand transcripts from 384 target genes of 365 miRNAs, which were enriched in the peroxisome, were validated by degradome-seq. An integrated analysis showed 42 miRNA–target pairs exhibited inversely related expression profiles. Among these pairs, a strong induction of gma-miR398c as a major gene negatively regulates multiple peroxisome-related genes (GmCSD1a/b, GmCSD2a/b/c and GmCCS). Meanwhile, we detected that alternative splicing of GmCSD1a/b might affect soybean drought tolerance by bypassing gma-miR398c regulation. Overexpressing gma-miR398c in Arabidopsis thaliana L. resulted in decreased percentage germination, increased leaf water loss, and reduced survival under water deficiency, which displayed sensitivity to drought during seed germination and seedling growth. Furthermore, overexpressing gma-miR398c in soybean decreased GmCSD1a/b, GmCSD2a/b/c and GmCCS expression, which weakened the ability to scavenge O2.−, resulting in increased relative electrolyte leakage and stomatal opening compared with knockout miR398c and wild-type soybean under drought conditions. Conclusion The study indicates that gma-miR398c negatively regulates soybean drought tolerance, and provides novel insights useful for breeding programs to improve drought resistance by CRISPR technology.

Diacylglycerol kinase (DGK) is recognized as the key enzyme of the lipid signaling pathway, which involves the transduction of messages from hormones, neurotransmitters, and immunologic and growth factors. Regarding their essential role in animal physiology, many plant biologists have predicted a similar enzymatic influence in plants. However, a small number of recent studies have revealed the complexity of the involvement of DGK genes in the modulation of plant growth, development, and adaptation in both biotic and abiotic stress conditions. Here, we describe recent discoveries on the role of DGK genes in the plants’ responses to biotic or abiotic stressors. Moreover, we discuss how DGK enzymes regulate plant cellular activities during the adaptation of plants to a readily changing environment. DGK is an enzyme that plays a pivotal role in plant lipid signaling, by catalyzing the phosphorylation of the diacylglycerol (DAG) to phosphatidic acid (PA), which is a crucial molecule in a plant’s metabolic network, leading to its response to various external stresses. DGK enzymes are the principal moderators of PA generation in plant cells; this consequently affects its derived products—hence, enabling their activities in lipid signaling networks and cell homeostasis. Thus, understanding the DGK operational mode and interactions between the production and accumulation of PA would constitute a significant advancement in investigating the mechanism of stress adaptation in plants.

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