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Halogeton glomeratus (H. glomeratus) is one of the most important halophytes in Asia, and the research on the genes and salt-tolerant mechanisms of this species is limited because of the lack of an optimal and efficient in vitro regeneration system. Here, we developed an efficient plant regeneration protocol using H. glomeratus leaves as explants, which has not been previously reported. High-quality calli were successfully obtained from the H. glomeratus leaves at a frequency of 100% supplemented with 2.00 mg/L 2,4-dichlorophenoxyacetic acid, 0.50 g/L PVP, 5.00 g/L agar, and 30.00 g/L sucrose; the optimum callus subculture medium is 1.00 mg/L 2,4-dichlorophenoxyacetic acid, 0.50 g/L PVP, 5.00 g/L agar, and 30.00 g/L sucrose. Shoots were regenerated on shoot induction medium at a frequency of 100% added with 0.50 mg/L 6-benzylaminopurine, 2.00 mg/L kinetin, 0.20 mg/L naphthaleneacetic acid, 0.50 g/L PVP, 5.00 g/L agar, and 30.00 g/L sucrose; then, shoots grew up on shoot regeneration medium. Finally, roots were regenerated from the shoots on Murashige and Skoog medium with high efficiency. This study firstly offers a rapid and efficient system for plantlet regeneration from leaves of H. glomeratus. Whether our protocol applies well to other tissue regeneration of H. glomeratus needs further confirmation. This work will facilitate basic research and salt-tolerant mechanisms of this important halophyte species. [ABSTRACT FROM AUTHOR]

Abstract Compartmentalization of Na+ into vacuoles is considered to be the most critical aspect of salt tolerance in H. glomeratus , an annual, succulent halophyte. Previous analysis of transcriptome involved in the H. glomeratus salt stress response relied on next-generation sequencing technologies that limit the capture of accurately spliced, full-length isoforms. To gain deeper insights into its salt stress response, we used the H. glomeratus Iso-Seq transcriptome database as a reference, and subsequent next-generation sequencing was subjected to various NaCl concentrations of leaves from plants revealed 115 upregulated and 87 downregulated differentially expressed isoforms (core DEIs). The majority of the core DEIs were involved in carbohydrate metabolism and energy production and conversion. In contrast, levels of known isoforms encoding Na+ transporters did not change significantly under salt stress. However, 16 core DEIs of unknown function were predicted to possess transmembrane domains, suggesting that these candidate isoforms could be involved in Na+ transport in H. glomeratus. These results suggest a potential means for identification of novel Na+ transporters, in addition to providing a foundation for further investigation of Na+ transport networks in halophytes. Highlights • Na+ Compartmentalization of into vacuoles is the most critical aspect of salt tolerance in H. glomeratus. • In H. glomeratus , ion transporters that are involved in vacuolar Na+ compartmentalization differ from other halophytes. • Results suggest a potential means for identification of novel Na+ transporters in H. glomertaus. [ABSTRACT FROM AUTHOR]

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. 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. [Display omitted] • Halogeton glomeratus (H. glomeratus) is categorized as a halophyte, but it has robust resistance to Cd2+ stress. • A DIA-based proteomic technique was used to investigate the molecular mechanisms for Cd2+ stress in H. glomeratus. • Numerous biological processes and regulators were related to Cd2+ stress in H. glomeratus. [ABSTRACT FROM AUTHOR]

Very little is known about the adaptation mechanism of Chenopodiaceae H alogeton glomeratus, a succulent annual halophyte, under saline conditions. In this study, we investigated the morphological and physiological adaptation mechanisms of seedlings exposed to different concentrations of NaCl treatment for 21 d. Our results revealed that H . glomeratus has a robust ability to tolerate salt; its optimal growth occurs under approximately 100 m m NaCl conditions. Salt crystals were deposited in water-storage tissue under saline conditions. We speculate that osmotic adjustment may be the primary mechanism of salt tolerance in H . glomeratus, which transports toxic ions such as sodium into specific salt-storage cells and compartmentalizes them in large vacuoles to maintain the water content of tissues and the succulence of the leaves. To investigate the molecular response mechanisms to salt stress in H . glomeratus, we conducted a comparative proteomic analysis of seedling leaves that had been exposed to 200 m m NaCl for 24 h, 72 h and 7 d. Forty-nine protein spots, exhibiting significant changes in abundance after stress, were identified using matrix-assisted laser desorption ionization tandem time-of-flight mass spectrometry ( MALDI- TOF/ TOF MS/ MS) and similarity searches across EST database of H . glomeratus. These stress-responsive proteins were categorized into nine functional groups, such as photosynthesis, carbohydrate and energy metabolism, and stress and defence response. [ABSTRACT FROM AUTHOR]