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Seaweeds are rich in essential dietary minerals, often lacking in terrestrial plant foods, with interest in Australian seaweeds rapidly increasing. We screened six Australian brown seaweeds with commercial potential for dietary mineral composition: Cystophora torulosa, Caulocystis uvifera, Durvillaea potatorum, Ecklonia radiata, Hormosira banksii and Phyllospora comosa. Spatial replicates of each species were collected from three non-urbanised sites remote from pollution sources and processed for human consumption. Dried samples were analysed by inductively coupled plasma mass spectrometry (ICP-MS) for 12 essential dietary minerals. Overall dietary mineral composition differed significantly amongst all species, except between sargassaceous species C. torulosa and C. uvifera; but concentrations of individual elements varied in complex ways. All species investigated had high concentrations of dietary minerals essential for optimal human health if consumed in realistic quantities (e.g. 10 g day−1 DW) as part of balanced diets, including the most common dietary minerals deficient in humans (iodine, iron, zinc, magnesium, calcium and selenium): iodine (888 ± 100 mg kg−1 DW) and zinc were highest in P. comosa; iron and calcium were highest in C. torulosa, but calcium was also high in E. radiata, H. banksii and D. potatorum; magnesium was highest in H. banksii, D. potatorum and P. comosa; selenium concentrations exceeded those previously reported for seaweeds for all species, except D. potatorum. The best nutritional outcomes may be achieved by regularly consumption of a diversity of seaweed species. However, further investigation into ways to reduce iodine content in some species may be required to maximise health benefits from regular consumption of these Australian seaweeds. [ABSTRACT FROM AUTHOR]

Introduction: Chestnut rot caused by the fungus Gnomoniopsis smithogilvyi is a disease present in the world's major chestnut growing regions. The disease is considered a significant threat to the global production of nuts from the sweet chestnut (Castanea sativa). Conventional fungicides provide some control, but little is known about the potential of biological control agents (BCAs) as alternatives to manage the disease. Objective: Evaluate whether formulated BCAs and their secreted metabolites inhibit the in vitro growth of G. smithogilvyi. Methods: The antifungal potential of BCAs was assessed against the pathogen through an inverted plate assay for volatile compounds (VOCs), a diffusion assay for non-volatile compounds (nVOCs) and in dual culture. Methanolic extracts of nVOCs from the solid medium were further evaluated for their effect on conidia germination and were screened through an LC–MS-based approach for antifungal metabolites. Results: Isolates of Trichoderma spp., derived from the BCAs, significantly suppressed the pathogen through the production of VOCs and nVOCs. The BCA from which Bacillus subtilis was isolated was more effective in growth inhibition through the production of nVOCs. The LC–MS based metabolomics on the nVOCs derived from the BCAs showed the presence of several antifungal compounds. Conclusion: The results show that G. smithogilvyi can be effectively controlled by the BCAs tested and that their use may provide a more ecological alternative for managing chestnut rot. The in vitro analysis should now be expanded to the field to assess the effectiveness of these alternatives for chestnut rot management. [ABSTRACT FROM AUTHOR]

Metal-hyperaccumulating plants have the ability to take up extraordinary quantities of certain metal ions without succumbing to toxic effects. Most hyperaccumulators select for particular metals but the mechanisms of selection are not understood at the molecular level. While there are many metal-binding biomolecules, this review focuses only on ligands that have been reported to play a role in sequestering, transporting or storing the accumulated metal. These include citrate, histidine and the phytosiderophores. The metal detoxification role of metallothioneins and phytochelatins in plants is also discussed. [ABSTRACT FROM AUTHOR]

Introduction: Mass spectrometry imaging (MSI) is a technology that enables the visualization of the spatial distribution of hundreds to thousands of metabolites in the same tissue section simultaneously. Roots are below-ground plant organs that anchor plants to the soil, take up water and nutrients, and sense and respond to external stresses. Physiological responses to salinity are multifaceted and have predominantly been studied using whole plant tissues that cannot resolve plant salinity responses spatially.Objectives: This study aimed to use a comprehensive approach to study the spatial distribution and profiles of metabolites, and to quantify the changes in the elemental content in young developing barley seminal roots before and after salinity stress.Methods: Here, we used a combination of liquid chromatography-mass spectrometry (LC-MS), inductively coupled plasma mass spectrometry (ICP-MS), and matrix-assisted laser desorption/ionization (MALDI-MSI) platforms to profile and analyze the spatial distribution of ions, metabolites and lipids across three anatomically different barley root zones before and after a short-term salinity stress (150 mM NaCl).Results: We localized, visualized and discriminated compounds in fine detail along longitudinal root sections and compared ion, metabolite, and lipid composition before and after salt stress. Large changes in the phosphatidylcholine (PC) profiles were observed as a response to salt stress with PC 34:n showing an overall reduction in salt treated roots. ICP-MS analysis quantified changes in the elemental content of roots with increases of Na+ and decreases of K+ content.Conclusion: Our results established the suitability of combining three mass spectrometry platforms to analyze and map ionic and metabolic responses to salinity stress in plant roots and to elucidate tolerance mechanisms in response to abiotic stress, such as salinity stress. [ABSTRACT FROM AUTHOR]

The extraordinary level of accumulation of nickel (Ni) in hyperaccumulator plants is a consequence of specific metal sequestering and transport mechanisms, and knowledge of these processes is critical for advancing an understanding of transition element metabolic regulation in these plants. The Ni biopathways were elucidated in three plant species, Phyllanthus balgooyi, Phyllanthus securinegioides (Phyllanthaceae) and Rinorea bengalensis (Violaceae), that occur in Sabah (Malaysia) on the Island of Borneo. This study showed that Ni is mainly concentrated in the phloem in roots and stems (up to 16.9% Ni in phloem sap in Phyllanthus balgooyi) in all three species. However, the species differ in their leaves - in P. balgooyi the highest Ni concentration is in the phloem, but in P. securinegioides and R. bengalensis in the epidermis and in the spongy mesophyll (R. bengalensis). The chemical speciation of Ni2+ does not substantially differ between the species nor between the plant tissues and transport fluids, and is unambiguously associated with citrate. This study combines ion microbeam (PIXE and RBS) and metabolomics techniques (GC-MS, LC-MS) with synchrotron methods (XAS) to overcome the drawbacks of the individual techniques to quantitatively determine Ni distribution and Ni2+ chemical speciation in hyperaccumulator plants. [ABSTRACT FROM AUTHOR]