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Quinoa (Chenopodium quinoa wild.), a dicotyledonous plant native to the Andes, is an increasingly popular pseudograin owing to its high nutritional value, stress resistance capabilities, and gluten-free properties. In this study, we aimed to explore the dynamic changes in different varieties of quinoa at the seedling stage and their regulatory networks. Here, we found that the leaves of quinoa showed obvious coloration after 45 days, and four quinoa seedling types (red, white, yellow, and black) were subjected to ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) and transcriptome sequencing to identify their differentially expressed genes and metabolites. A total of 29 differential metabolites and 19 genes (14 structural and 5 regulatory genes) were identified, and consistent differences were observed in the flavonoid, phenolic acid, and alkaloid metabolites in the different quinoa types. These differential metabolites were significantly enriched in flavonoid and flavonol biosynthesis, flavonoid biosynthesis, and phenylpropanoid biosynthesis pathways. In addition, real-time fluorescence quantitative PCR (RT-qPCR) technology was used to detect the expression of four structural genes involved in the flavonoid biosynthesis pathway and four regulatory genes (interaction network). The results revealed that the structural and regulatory gene transcript levels in the flavonoid pathway were higher in the red quinoa cultivars than in the white, yellow, and black. Additionally, the differences in the leaves of these four quinoa cultivars were mainly due to differences in flavonoid, phenolic acid, and alkaloid accumulation. Our findings provide a basis for understanding the accumulation and coloration mechanisms of flavonoids, phenolic acids, and alkaloids in quinoa seedlings of different colors and also provide a theoretical basis for future investigations. [ABSTRACT FROM AUTHOR]

Background: Quinoa (Chenopodium quinoa Willd.) originates in high altitude areas, such as the Andes, and has some inherent characteristics of cold, drought, and salinity tolerance, but is sensitive to high temperature. Results: To gain insight into the response mechanism of quinoa to high temperature stress, we conducted an extensive targeted metabolomic study of two cultivars, Dianli-3101 and Dianli-3051, along with a combined transcriptome analysis. A total of 794 metabolites and 54,200 genes were detected, in which the genes related to photosynthesis were found down-regulated at high temperatures, and two metabolites, lipids and flavonoids, showed the largest changes in differential accumulation. Further analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and transcription factors revealed that quinoa inhibits photosynthesis at high temperatures, and the possible strategies being used for high temperature stress management are regulation of heat stress transcription factors (HSFs) to obtain heat tolerance, and regulation of purine metabolism to enhance stress signals for rapid response to high temperature stress. The tolerant genotype could have an enhanced response through lower purine levels. The induction of the stress response could be mediated by HSF transcription factors. The results of this study may provide theoretical references for understanding the response mechanism of quinoa to high temperature stress, and for screening potential high temperature tolerant target genes and high temperature tolerant strains. Conclusions: These findings reveal the regulation of the transcription factor family HSF and the purinergic pathway in response to high temperature stress to improve quinoa varieties with high temperature tolerance. [ABSTRACT FROM AUTHOR]