Understanding the chemical foundation and genetic mechanism of the black grain trait in quinoa by integrating metabolome and transcriptome analyses

Figures & data

Table 1. Summary of the chemical compounds in black and white grains.

Category	Total compounds	Differentially accumulated compounds	Percent (%)	Up-accumulated compounds	Down-accumulated compounds
Tannins	13	13	100.00	13	0
Flavonoids	117	69	58.97	62	7
Phenolic acids	36	14	38.89	3	11
Terpenoids	8	3	37.50	2	1
Lignans and coumarins	12	4	33.33	0	4
Amino acids and derivatives	44	12	27.27	9	3
Organic acids	24	6	25.00	3	3
Alkaloids	33	8	24.24	5	3
Nucleotides and derivatives	38	9	23.68	5	4
Lipids	63	13	20.63	0	13
Others	58	6	10.34	1	5
Total	446	157	35.20	103	54

Figure 1. KEGG enrichment analysis for differentially expressed genes between black and white quinoa grains.

Figure 2. Expression differences between structural genes involved in flavonoids biosynthesis. The arrows show the enzyme-encoding genes and the metabolic stream. The red font indicates the differentially expressed genes encoding enzymes, and the blue font indicates the differential metabolites. The number represents the expression in the black grain relative to that in the white grain [=expression (black)/expression (white)]. The numbers under the chemical compounds represent the relative contents of the compounds accumulated in the black grain versus the white grain. These structural flavonoid biosynthesis genes and chemical compounds were more significantly upregulated in black grain than in white grain.

Figure 3. Expression differences of unigenes involved in betalain biosynthesis. The arrows show the enzyme-encoding genes and the metabolic stream. The red font indicates the differentially expressed genes encoding enzymes, and the blue font indicates the differential metabolites. The numbers represent the expression in the black grain relative to that in the white grain (log₂FC). The numbers under the chemical compounds represent the relative contents of the compounds accumulated in the black grain versus the white grain.

Figure 4. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment histogram of conjoint analysis of differentially expressed genes and accumulated metabolites. The X-axis represents the metabolic pathways; the Y-axis represents the expression as –log (p value). The red columns represent the enrichment p values of differentially expressed genes, and the green columns represent the enrichment p values of different metabolites.