Comparative transcriptome analysis of genes involved in Na+ transport in the leaves of halophyte Halogeton glomeratus

HgS2, a novel salt-responsive gene from the Halophyte Halogeton glomeratus, confers salt tolerance in transgenic Arabidopsis

Halophyte Halogeton glomeratus mostly grows in saline desert areas in arid and semi-arid regions and is able to adapt to adverse conditions such as salinity and drought. Earlier transcriptomic studies revealed activation of the HgS2 gene in the leaf of H. glomeratus seedlings when exposed to saline conditions. To identify the properties of HgS2 in H. glomeratus, we used yeast transformation and overexpression in Arabidopsis. Yeast cells genetically transformed with HgS2 exhibited K+ uptake and Na+ efflux compared with control (empty vector). Stable overexpression of HgS2 in Arabidopsis improved its resistance to salt stress and led to a notable rise in seed germination in salinity conditions compared to the wild type (WT). Transgenic Arabidopsis regulated ion homeostasis in plant cells by increasing Na+ absorption and decreasing K+ efflux in leaves, while reducing Na+ absorption and K+ efflux in roots. In addition, overexpression of HgS2 altered transcription levels of stress response genes and regulated different metabolic pathways in roots and leaves of Arabidopsis. These results offer new insights into the role of HgS2 in plants' salt tolerance.

Proteomic analysis reveals molecular mechanism of Cd2+ tolerance in the leaves of halophyte Halogeton glomeratus

Halogeton glomeratus (H. glomeratus) is categorized as a halophyte, it can potentially endure not only salt but also heavy metals. The aim of this work was to study the molecular mechanisms underlying the Cd²⁺ tolerance of halophyte H. glomeratus seedlings. For that we used a combination of physiological characteristics and data-independent acquisition-based proteomic approaches. The results revealed that the significant changes of physiological characteristics of H. glomeratus occurred under approximately 0.4 mM Cd²⁺ condition and that Cd²⁺ accumulated in Cd²⁺-treated seedling roots, stems and leaves. At the early stage of Cd²⁺ stress, numerous differentially abundant proteins related to "phosphoenolpyruvate carboxylase", "transmembrane transporters", and "vacuolar protein sorting-associated protein" took important roles in the response of H. glomeratus to Cd²⁺ stress. At the later stage of Cd²⁺ stress, some differentially abundant proteins involved in "alcohol-forming fatty acyl-CoA reductase", "glutathione transferase", and "abscisic acid receptor" were considered to regulate the adaptation of H. glomeratus exposed to Cd²⁺ stress. Finally, we found various detoxification-related differentially abundant proteins related to Cd²⁺ stress. These biological processes and regulators synergistically regulated the Cd²⁺ tolerance of H. glomeratus. SIGNIFICANCE: The halophyte, H.glomeratus, has a strong tolerance to salinity, also survives in the heavy metal stress. At present, there are few reports on the comprehensive characterization and identification of Cd²⁺ response and adaption related regulators in H.glomeratus. This research focuses on the molecular mechanisms of H. glomeratus tolerance to Cd²⁺ stress at proteome levels to uncover the novel insight of the Cd²⁺-related biological processes and potential candidates involved in the response and adaption mechanism. The results will help elucidate the genetic basis of this species' tolerance to Cd²⁺ stress and develop application prospect of wild genetic resources to heavy metal phytoremediation.

Metabolomics Analyses Provide Insights Into Nutritional Value and Abiotic Stress Tolerance in Halophyte Halogeton glomeratus

Halogeton glomeratus is a succulent annual herbaceous halophyte belonging to the Chenopodiaceae family, has attracted wide attention as a promising candidate for phytoremediation and as an oilseed crop and noodle-improver. More importantly, H. glomeratus has important medicinal value in traditional Chinese medicine. However, there are few comprehensive studies on the nutrients, particularly secondary metabolites. Here, we adopted untargeted metabolomics to compare the differences in metabolites of different tissues (root, stem, leaf, and seed) and identify the compounds related to pharmacological effects and response to abiotic stress in H. glomeratus. A total of 2,152 metabolites were identified, and the metabolic profiles of root, stem, leaf, and seed samples were clearly separated. More than 50% of the metabolites showed significant differences among root, stem, leaf, and seed. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of differential metabolites suggested an extensive alteration in the metabolome among the different organs. Furthermore, the identified metabolites related to pharmacological effects and response to abiotic stress included flavones, flavonols, flavandiols, glucosinolates, isoquinolines, pyridines, indoles, amino acids, lipids, carbohydrates, and ATP-binding cassette transporters. These metabolites have application in treating human cardiovascular diseases, cancers, diabetes, and heart disease, induce sleeping and have nutritive value. In plants, they are related to osmotic adjustment, alleviating cell damage, adjusting membrane lipid action and avoiding toxins. To the best of our knowledge, this is the first metabolomics-based report to overview the metabolite compounds in H. glomeratus and provide a reference for future development and utilization of H. glomeratus.