Integrated morphological, physiological and transcriptomic analyses reveal the responses of Toona sinensis seedlings to low-nitrogen stress.

Nitrogen is one of the most essential elements for plant growth and development. In this study, the growth, physiology, and transcriptome of Toona sinensis (A. Juss) Roem seedlings were compared between low-nitrogen (LN) and normal-nitrogen (NN) conditions. These results indicate that LN stress adversely influences T. sinensis seedling growth. The activities of key enzymes related to nitrogen assimilation and phytohormone contents were altered by LN stress. A total of 2828 differentially expressed genes (DEGs) in roots and 1547 in leaves were identified between the LN and NN treatments. A differential enrichment analysis of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways indicated that nitrogen and sugar metabolism, flavonoid biosynthesis, plant hormone signal transduction, and ABC transporters, were strongly affected by LN stress. In summary, this research provides information for further understanding the response of T. sinensis to LN stress.

Metabolic profiling and gene expression analysis reveal the quality deterioration of postharvest toon buds between two different storage temperatures.

Toon buds, a popular woody vegetable, contain large amounts of nutrients. However, toon buds have strong respiratory metabolism after harvest and are highly prone to decay, resulting in quality deterioration. Low temperature can effectively inhibit postharvest senescence of toon buds. GC-TOF-MS combined with quantitative real-time PCR was used to elucidate the toon bud deterioration mechanism after harvest by analyzing the difference in the relative contents of primary metabolites and their derivatives, and the expression of key genes associated with metabolic pathways in toon buds between low temperature and room temperature storages for 72 h. Results showed that the ethylene synthesis in toon buds accelerated under room temperature storage, along with significant changes in the primary metabolic pathway. The catabolism of amino acids, fatty acids, and cell membrane phospholipids was accelerated, and the gluconeogenesis synthesis was strengthened. Moreover, the sucrose synthesis was increased, the glycolysis and TCA cycle were broken down, and the pentose phosphate pathway was vigorous. As metabolic intermediates, organic acids were considerably accumulated. Moreover, varieties of toxic compounds were produced in parallel with the activation of aromatic compounds. This work provided a comprehensive understanding of the metabolic regulation, thereby revealing how low and room temperatures differentially influenced the quality deterioration of postharvest toon buds.

Simultaneous determination of 10 kinds of biogenic amines in rat plasma using high-performance liquid chromatography coupled with fluorescence detection.

We describe a simple, rapid, selective and sensitive HPLC method coupled with fluorescence detection for simultaneous determination of 10 kinds of biogenic amines (BAs: tryptamine, 2-phenethylamine, putrescine, cadaverine, histamine, 5-hydroxytryptamine, tyramine, spermidine, dopamine and spermine). BAs and IS were derivated with dansyl chloride. Fluorescence detection (λex /λem = 340/510 nm) was used. A satisfactory result for method validation was obtained. The assay was shown to be linear over the ranges 0.005-1.0 µg/mL for tryptamine, 2-phenethylamine and spermidine, 0.025-1.0 µg/mL for putrescine, 0.001-1.0 µg/mL for cadaverine, 0.25-20 µg/mL for histamine, 0.25-10 µg/mL for 5-hydroxytryptamine and dopamine, and 0.01-1.0 µg/mL for tyramine and spermine. The limits of detection and the limits of quantification were 0.3-75.0 ng/mL and 1.0-250.0 ng/mL, respectively. Relative standard deviations were ≤5.14% for intra-day and ≤6.58% for inter-day precision. The recoveries of BAs ranged from 79.11 to 114.26% after spiking standard solutions of BAs into a sample at three levels. Seven kinds of BAs were found in rat plasma, and the mean values of tryptamine, 2-phenethylamine, putrescine, cadaverine, histamine, spermidine and spermine determined were 52.72 ± 7.34, 11.45 ± 1.56, 162.56 ± 6.26, 312.75 ± 18.11, 1306.50 ± 116.16, 273.89 ± 26.41 and 41.51 ± 2.07 ng/mL, respectively.

Overexpression of SlRBZ Results in Chlorosis and Dwarfism through Impairing Chlorophyll, Carotenoid, and Gibberellin Biosynthesis in Tomato.

ZFPs play important roles in many biological processes, including plant development, stress response, and phytohormone response. RanBP2-type zinc finger transcription factors have been characterized in animals and humans. However, their functions remain largely unknown in plants. In this study, we identified a RanBP2-type zinc finger protein gene (SlRBZ) in tomato. SlRBZ was constitutively expressed in roots, stems, leaves, flowers, and fruits. The SlRBZ-GFP fused protein was localized in the nucleus. Overexpression of SlRBZ resulted in chlorosis and dwarf phenotypes in tomato. Determination of physiological index showed that chlorophyll, carotenoid, and GAs contents were evidently decreased in transgenic plants. Furthermore, the qRT-PCR and RNA-Seq analyses demonstrated that the transcription of the genes involved in these biosynthesis pathways obviously decreased in SlRBZ-OE plants. In addition, ultrastructural observation by transmission electron microscopy indicated that plastids could not develop into mature chloroplasts with normal chloroplast membrane and thylakoid membrane system in SlRBZ-OE plants. The results suggest that overexpression of SlRBZ may impair the biosynthesis of chlorophyll, carotenoid, and gibberellin through blocking chloroplast development, resulting in chlorosis and dwarfism in tomato.