Magnesium enrichment and distribution in plants

Transcriptome sequencing and functional verification revealed the roles of exogenous magnesium in tobacco anti-PVY infection

Potato virus Y (PVY) infection causes necrosis and curling of leaves, which seriously affect the yield and quality of Solanaceous crops. The roles of nutrient elements in the regulation of plant resistance to virus infection has been widely reported, while the mechanisms are poorly studied. Previous studies in our laboratory have demonstrated that foliar spraying of MgSO4 could induce Nicotiana tabacum resistance to PVY by increasing the activity of defense-related enzymes. Consistent with the results, we found that exogenous magnesium (Mg) had a certain effect on N. tabacum anti-PVY infection. Meanwhile, Illumina RNA sequencing revealed that Mg induced resistance to PVY infection was mainly by regulating carbohydrate metabolism and transportation, nitrogen metabolism, Ca2+ signal transduction and oxidative phosphorylation. Moreover, we used virus-induced gene silencing assays to verify the function of homologs of five N. tabacum genes involved in above pathways in N. benthamiana. The results showed that NbTPS and NbGBE were conducive to PVY infection, while NbPPases and NbNR were related to resistance to PVY infection. These results suggested a novel strategy for resistance to PVY infection and provided a theoretical basis for virus-resistance breeding.

UV-C Seed Surface Sterilization and Fe, Zn, Mg, Cr Biofortification of Wheat Sprouts as an Effective Strategy of Bioelement Supplementation

Metalloenzymes play an important role in the regulation of many biological functions. An effective way to prevent deficiencies of essential minerals in human diets is the biofortification of plant materials. The process of enriching crop sprouts under hydroponic conditions is the easiest and cheapest to conduct and control. In this study, the sprouts of the wheat (Triticum aestivum L.) varieties Arkadia and Tonacja underwent biofortification with Fe, Zn, Mg, and Cr solutions in hydroponic media at four concentrations (0, 50, 100, and 200 µg g-1) over four and seven days. Moreover, this study is the first to combine sprout biofortification with UV-C (λ = 254 nm) radiation treatment for seed surface sterilization. The results showed that UV-C radiation was effective in suppressing seed germination contamination by microorganisms. The seed germination energy was slightly affected by UV-C radiation but remained at a high level (79-95%). The influence of this non-chemical sterilization process on seeds was tested in an innovative manner using a scanning electron microscope (SEM) and EXAKT thin-section cutting. The applied sterilization process reduced neither the growth and development of sprouts nor nutrient bioassimilation. In general, wheat sprouts easily accumulate Fe, Zn, Mg, and Cr during the applied growth period. A very strong correlation between the ion concentration in the media and microelement assimilation in the plant tissues (R2 > 0.9) was detected. The results of the quantitative ion assays performed with atomic absorption spectrometry (AAS) using the flame atomization method were correlated with the morphological evaluation of sprouts in order to determine the optimum concentration of individual elements in the hydroponic solution. The best conditions were indicated for 7-day cultivation in 100 µg g-1 of solutions with Fe (218% and 322% better nutrient accumulation in comparison to the control condition) and Zn (19 and 29 times richer in zinc concentration compared to the sprouts without supplementation). The maximum plant product biofortification with magnesium did not exceed 40% in intensity compared to the control sample. The best-developed sprouts were grown in the solution with 50 µg g-1 of Cr. In contrast, the concentration of 200 µg g-1 was clearly toxic to the wheat sprouts.

Liquid chromatography combined with mass spectrometry for 13C isotopic analysis in life science research

Among the different disciplines covered by mass spectrometry, measurement of (13)C/(12)C isotopic ratio crosses a large section of disciplines from a tool revealing the origin of compounds to more recent approaches such as metabolomics and proteomics. Isotope ratio mass spectrometry (IRMS) and molecular mass spectrometry (MS) are the two most mature techniques for (13)C isotopic analysis of compounds, respectively, for high and low-isotopic precision. For the sample introduction, the coupling of gas chromatography (GC) to either IRMS or MS is state of the art technique for targeted isotopic analysis of volatile analytes. However, liquid chromatography (LC) also needs to be considered as a tool for the sample introduction into IRMS or MS for (13)C isotopic analyses of non-volatile analytes at natural abundance as well as for (13)C-labeled compounds. This review presents the past and the current processes used to perform (13)C isotopic analysis in combination with LC. It gives particular attention to the combination of LC with IRMS which started in the 1990's with the moving wire transport, then subsequently moved to the chemical reaction interface (CRI) and was made commercially available in 2004 with the wet chemical oxidation interface (LC-IRMS). The LC-IRMS method development is also discussed in this review, including the possible approaches for increasing selectivity and efficiency, for example, using a 100% aqueous mobile phase for the LC separation. In addition, applications for measuring (13)C isotopic enrichments using atmospheric pressure LC-MS instruments with a quadrupole, a time-of-flight, and an ion trap analyzer are also discussed as well as a LC-ICPMS using a prototype instrument with two quadrupoles.

Application of enriched stable isotopes as tracers in biological systems: a critical review

The application of enriched stable isotopes of minerals and trace elements as tracers in biological systems is a rapidly growing research field that benefits from the many new developments in inorganic mass spectrometric instrumentation, primarily within inductively coupled plasma mass spectrometry (ICP-MS) instrumentation, such as reaction/collision cell ICP-MS and multicollector ICP-MS with improved isotope ratio measurement and interference removal capabilities. Adaptation and refinement of radioisotope tracer experiment methodologies for enriched stable isotope experiments, and the development of new methodologies coupled with more advanced compartmental and mathematical models for the distribution of elements in living organisms has enabled a broader use of enriched stable isotope experiments in the biological sciences. This review discusses the current and future uses of enriched stable isotope experiments in biological systems.