Combining Metabolomics and Transcriptomics to Reveal the Mechanism of Coloration in Purple and Cream Mutant of Sweet Potato (Ipomoea batatas L.)

Abstract

Purple sweet potato is considered as a healthy food because of its high anthocyanins. To understand the coloring mechanism and quality change between purple-fleshed sweet potato (cv. Xuzi201) and its cream fleshed mutant (M1001), a combined metabolomic and transcriptomic analysis was performed. The metabolome data showed that 4 anthocyanins, 19 flavones, 6 flavanones, and 4 flavonols dramatically decreased in M1001, while the contents of 3 isoflavones, 3 flavonols, 4 catechins, and 2 proanthocyanins increased. Transcriptomic analyses indicated that the expression of 49 structural genes in the flavonoid pathway and transcription factors (TFs) (e.g., bHLH2, R2R3-MYB, MYB1) inducting anthocyanin biosynthesis were downregulated, but the repressor MYB44 was upregulated. The IbMYB1-2 gene was detected as a mutation gene in M1001, which is responsible for anthocyanin accumulation in the storage roots. Thus, the deficiency of purple color in the mutant is due to the lack of anthocyanin accumulation which was regulated by IbMYB1. Moreover, the accumulation of starch and aromatic volatiles was significantly different between Xuzi201 and M1001. These results not only revealed the mechanism of color mutation but also uncovered certain health-promoting compounds in sweet potato.

Regulatory network characterization of anthocyanin metabolites in purple sweetpotato via joint transcriptomics and metabolomics

“…Nevertheless, the significantly differentiated central anthocyanin metabolic network between the purple and non-purple sweet potato materials still sheds light on the anthocyanin component divergence. In our study, 14 categories of anthocyanin, including one glycosylated pelargonidin, one glycosylated petunidin, one malvidin, five glycosylated peonidin, and six glycosylated cyanidin, were recognized, whereas there were only seven or eight kinds identified in a previous study Zhang et al, 2022). Despite the technical difficulty in accurately verifying the monomer of anthocyanin (Li et al, 2012), we still detected more glycosylated derivatives in the purple sweet potatoes DZ88 and DZ54 (Table 1), which all displayed higher accumulation than the others.…”

“…Hence, the reallocation of intermediate substrates, which was largely determined by the expression of specific genes (e.g. FLS), demonstrated that the transcriptional discrepancy in the gene expressions and the gene-metabolite interactions might have played a crucial role in the metabolite flux repartitioning, which thereafter caused the distinct pigmentary performances in the purple and non-purple sweet potatoes (Zhang et al, 2022).…”

“…To support that, the given molecular mechanisms underlying the anthocyanin anabolism in the purple sweet potato root flesh, which is the primary economic organ for harvesting, should be investigated in-depth, particularly in the regional germplasms that have had more genetic variations relative to the existing cultivars (Mano et al, 2007;Liu et al, 2017). The known knowledge of other plants, such as Arabidopsis (Arabidopsis thaliana) (He et al, 2020), apple (Malus domestica) (Zhang et al, 2019), tomato (Solanum lycopersicum) (Sun et al, 2020), as well as the recently reported studies in purple sweet potato (Zhang et al, 2022;Zhao et al, 2022), would provide a solid reference foundation for relevant research.…”

Widely Targeted Metabolomics Provides New Insights into Nutritional Profiling and Reveals the Flavonoid Pathway of Pea (Pisum sativum L.)

“…A total of 33 isoflavones from peas were detected in this study, and most of them were much richer in dried peas than fresh peas, but sophoricoside, genistein-7-O-galactoside, and 4′,5-dihydroxyisoflavone-7-O-galactoside were accumulated in fresh peas (Figure 5). Moreover, we summarized the kinds and numbers of isoflavones from fruits [43,44], staple food crops [1], coarse cereals [18,45], tuber crops [46][47][48], and vegetables [49][50][51][52][53] in recent reports. They were characterized using the same metabolomic detection platform of MetWare.…”

Color and Nutritional Analysis of Ten Different Purple Sweet Potato Varieties Cultivated in China via Principal Component Analysis and Cluster Analysis

“…Purple sweet potato (PSP) ( Ipomoea batatas L.), a member of the sweet potato family, exhibits an intense purple color in the root and skins owing to the accumulation of anthocyanins [ 1 ]. As one of the most promising economic crops, PSP contains abundant amounts of nutrients.…”