Nitrogen (N) is an essential mineral element for plants and is the main component of protein, nucleic acid, phospholipid, chlorophyll, hormones, vitamins and alkaloids. It is involved in all stages of plant growth and development. Low-N stress seriously hinders plant growth and reduces yield and quality. Plants have evolved a series of elaborate regulatory mechanisms for N uptake and assimilation to cope with different soil N states. After N is absorbed and utilized by plants, it plays important regulatory roles in phytohormones, microRNA (miRNA), root development and mycorrhizal symbiosis to cope with environmental stress. Here, we highlight the research progress on the regulation mechanisms for N absorption and assimilation. Then, we emphasize the regulation roles of N regarding hormone signals, miRNA, lateral root growth, drought resistance, anthocyanin synthesis and mycorrhizal symbiosis. A thorough understanding of N uptake, utilization and interaction with other biological processes is helpful to improve N use efficiency and to breed plants with “less-input-more-output”.

Dracocephalum moldavica is widely used as an ornamental, medicine, and perfume in industry. Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) is widely and accurately utilized for gene expression evaluations. Selecting optimal reference genes is essential for normalizing RT-qPCR results. However, the identification of suitable reference genes in D. moldavica has not been documented. A total of 12 reference genes in D. moldavica were identified by PEG6000 (15%) treatment under hypertonia conditions in different tissues (roots, stem, leaves, flower, seeds and sepal) and during three stages of flower development, then used to validate the expression stability. There were four algorithms (delta Ct, geNorm, NormFinder, and BestKeeper) used to analyze the stability. Finally, the RefFinder program was employed to evaluate the candidate reference genes’ stability. The results showed that ACTIN, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and EF1α (elongation factor-1α) were stable reference genes under the PEG6000 treatment. Heat shock protein 70 (HSP70) was the most stable gene across different flower development stages. ADP-ribosylation factor (ARF) was the most stable gene in different tissues and total samples. This study provides reliable gene expression studies for future research in D. moldavica.

Lacquer trees (Toxicodendron vernicifluum), economically vital, face high-temperature stress in summer. Transcriptomic, proteomic, and metabolomic analyses were employed to investigate the mechanisms by which lacquer trees respond to high temperatures. High-temperature treatment led to notable metabolite changes with 224 upregulated and 69 downregulated. Indole-3-acetic acid remained stable while abscisic acid decreased, with increases in jasmonic acid and jasmonoyl-L-isoleucine indicating complex hormonal responses. JAR1 and ABA 8′-hydroxylase encoding genes were upregulated. The rise in JAs boosted the alkaloid content and activated nitrogen transport. High temperatures also increased specific amino acids and upregulated aminotransferase and protease-encoding genes. Metabolomic analysis showed elevated flavonoid glycosides and the upregulation of glycosyltransferase genes. WPCNA found 35 protein modules involved in secondary metabolite biosynthesis, protein phosphorylation, and signal transduction. Protein–protein interaction analysis revealed MYC6’s link with flavonoid biosynthesis, indicating its role in promoting flavonoids.

The lacquer tree (Toxicodendron vernicifluum) possesses significant economic value due to its capability to produce raw lacquer, lacquer wax, and lacquer oil. The fruit is the primary source of lacquer wax; the primary components of lacquer wax are fatty acids, yet the synthesis mechanisms of fatty acids and wax esters remain unclear. In this study, we employed RNA-seq to analyze differentially expressed genes (DEGs) across four developmental stages in the fruit of the lacquer tree. The results revealed that, compared to the T1 stage, there were 1736, 10,228, and 12,444 DEGs in the three developmental stages. Through KEGG enrichment analysis, DEGs associated with lacquer wax synthesis were found to be primarily enriched in fatty acid metabolism, degradation, and the biosynthesis of cutin, suberin, and wax esters pathways. Furthermore, analysis of DEGs expression patterns in fatty acid synthesis pathways revealed that ACC, KAS, KAR, FATB, and FAD were significantly differentially expressed. Additionally, LACS, WSD1, CER4, CER1, and MAH1 participated in wax biosynthesis. Moreover, one co-expression network among wax biosynthesis genes, hormone signal transduction genes, and transcription factors was established. These findings provide a theoretical foundation for identifying key genes involved in regulating fatty acid and lacquer wax synthesis in Toxicodendron vernicifluum.