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[Objective] Phosphorus absorption and utilization by plants mainly depend on phosphorus transporters, among which the low-affinity phosphorus transporters encoded by the PHT2 family are responsible for the absorption, transport and reuse of phosphate by plants under normal phosphorus conditions. We aim to explore the role and expression pattern of NtPHT2;1 gene in tobacco phosphate transport, and to cultivate new tobacco varieties with efficient phosphorus utilization through NtPHT2;1. [Methods] We cloned NtPHT2;1 using the cDNA of a common tobacco K326 as a template, and conducted bioinformatics analysis and subcellular localization analysis of the protein. The expression pattern of this gene under abiotic stress including low phosphorus were analyzed by fluorescence quantitative PCR. [Results] (1) The total length of NtPHT2;1 gene was 1 764 bp, encoding 587 amino acids. (2) NtPHT2;1 protein was localized to chloroplast. (3) The homology between NtPHT2;1 and CaPHT2;1 protein was 91%. (4) Nt- PHT2;1 promoter contains cis-acting elements involved in the regulation of plant aging and stress. (5) The expression of NtPHT2;1 was the highest in leaves, and expression in new leaves was higher than that in old leaves. There was no significant difference in the expression of this gene under low phosphorus compared with normal conditions. (6) The expression of this gene was decreased significantly under salt stress and drought stress. [Conclusion] NtPHT2;1 gene is involved in phosphate transport and utilization in growth and development of tobacco plants.

To investigate the role of auxin-induced gene NtIAA13 in potassium uptake and utilization in tobacco, a gene designated NtIAA13b with a total length of 879 bp and encoding 292 amino acids was cloned using the cDNA of tobacco K326 as a template. The expression characteristics of NtIAA13b in different tissues under different abiotic stress conditions were systematically analyzed by qRT-PCR and subcellular localization, and the overexpression strain of NtIAA13b was obtained by transgenic technology to verify its physiological function. The results showed that the protein encoded by NtIAA13b had a relative molecular mass of 31.71 kD and a theoretical isoelectric point(pI)of 6.48. The promoter region of NtIAA13b contained auxin-responsive element TGA-element and gibberellin-responsive element P-box, as well as regulatory element ARE that was involved in anaerobic induction. The subcellular localization results showed that the protein was localized in the nucleus. The phylogenetic tree results showed that NtIAA13b and tomato SlIAA13 were closely related. The real-time PCR results showed that NtIAA13b had the highest expression level in roots, followed by stalks and leaves with the lowest expression levels. Under normal potassium supply conditions, overexpressed strains significantly increased leaf potassium content. The NtIAA13b gene is thus associated with tobacco response to hypokalemic stress and may be involved in the uptake and utilization of potassium in tobacco. [ABSTRACT FROM AUTHOR]

In order to study the role of nitrate transporter (NRT) in the uptake and transport of nitrate in tobacco, a nitrate transporter gene encoding 612 amino acids with a total length of 1 839 bp was cloned using the cDNA of tobacco cultivar K326 as a template and named as NtNRT1.7. Bioinformatics analysis indicated that NtNRT1.7 had typical transmembrane domains. The homology analysis showed that the homology of NtNRT1.7 and Arabidopsis thaliana AtNRT1.7 was 57.23%. Subcellular localization results showed that this protein was located on the cell membrane and was a typical membrane protein. Promoter analysis and QRT-PCR results of different stress treatments indicated that NtNRT1.7 gene was highly expressed in mature leaves, its expression was suppressed by low nitrogen and enhanced by drought, low temperature, high salt and other stresses, which suggested that NtNRT1.7 gene might be involved in nitrate recycle under abiotic stresses. [ABSTRACT FROM AUTHOR]

Temperature is a primary factor affecting the rate of plant development; as the climate warms, extreme temperature events are likely to increasingly affect agriculture. Understanding how to improve crop tolerance to heat stress is a key concern. Wild plants have evolved numerous strategies to tolerate environmental conditions, notably the regulation of root architecture by phytohormones, but the molecular mechanisms of stress resistance are unclear. In this study, we showed that high temperatures could significantly reduce tobacco biomass and change its root architecture, probably through changes in auxin content and distribution. Overexpression of the OsPT8 phosphate transporter enhanced tobacco tolerance to high-temperature stress by changing the root architecture and increased the antioxidant ability. Molecular assays suggested that overexpression of OsPT8 in tobacco significantly increased the expression of auxin synthesis genes NtYUCCA 6, 8 and auxin efflux carriers genes NtPIN 1,2 under high-temperature stress. We also found that the expression levels of auxin response factors NtARF1 and NtARF2 were increased in OsPT8 transgenic tobacco under high-temperature stress, suggesting that OsPT8 regulates auxin signaling in response to high-temperature conditions. Our findings provided new insights into the molecular mechanisms of plant stress signaling and showed that OsPT8 plays a key role in regulating plant tolerance to stress conditions. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is an environmental pollutant that potentially threatens human health worldwide. Developing approaches for efficiently treating environmental Cd is a priority. Selenium (Se) plays important role in the protection of plants against various abiotic stresses, including heavy metals. Previous research has shown that Se can alleviate Cd toxicity, but the molecular mechanism is still not clear. In this study, we explore the function of auxin and phosphate (P) in tobacco (Nicotiana tabacum), with particular focus on their interaction with Se and Cd. Under Cd stress conditions, low Se (10 μM) significantly increased the biomass and antioxidant capacity of tobacco plants and reduced uptake of Cd. We also measured the auxin concentration and expression of auxin-relative genes in tobacco and found that plants treated with low Se (10 μM) had higher auxin concentrations at different Cd supply levels (0 μM, 20 μM, 50 μM) compared with no Se treatment, probably due to increased expression of auxin synthesis genes and auxin efflux carriers. Overexpression of a high affinity phosphate transporter NtPT2 enhanced the tolerance of tobacco to Cd stress, possibly by increasing the total P and Se content and decreasing Cd accumulation compared to that in the wild type (WT). Our results show that there is an interactive mechanism among P, Se, Cd, and auxin that affects plant growth and may provide a new approach for relieving Cd toxicity in plants. [ABSTRACT FROM AUTHOR]

A method was developed for the determination of eight synthetic pigments in beverage samples by liquid–liquid microextraction followed by high performance liquid chromatography. Using hydrophobic deep eutectic solvent (DES) as the microextraction solvent, several key parameters were optimized, including the type and volume of the hydrophobic DES, pH value, vortex time and salt content. Detection limits were in the range 0.016–1.12 ng/mL, recoveries were in the range 74.5–102.5% and relative standard deviations were <5.4%. The method is simple, green and practical, and could be applied to the extraction and determination of synthetic pigments in beverages. [ABSTRACT FROM AUTHOR]