Sweetpotato [Ipomoea batatas (L.) Lam.] is a globally important staple food crop, especially for sub-Saharan Africa. Agronomic improvement of sweetpotato has lagged behind other major food crops due to a lack of genomic and genetic resources and inherent challenges in breeding a heterozygous, clonally propagated polyploid. Here, we report the genome sequences of its two diploid relatives, I. trifida and I. triloba, and show that these high-quality genome assemblies are robust references for hexaploid sweetpotato. Comparative and phylogenetic analyses reveal insights into the ancient whole-genome triplication history of Ipomoea and evolutionary relationships within the Batatas complex. Using resequencing data from 16 genotypes widely used in African breeding programs, genes and alleles associated with carotenoid biosynthesis in storage roots are identified, which may enable efficient breeding of varieties with high provitamin A content. These resources will facilitate genome-enabled breeding in this important food security crop.

Anthocyanins and hydroxycinnamic acid derivatives in the crude extracts of peel, flesh, and whole roots of 10 Chinese purple-fleshed sweetpotato genotypes were simultaneously characterized by liquid chromatography-photodiode array detector-atmospheric pressure chemical ionization-mass spectrometry (LC-PDA-APCI-MS), as well as their antioxidant activities were systematically investigated and compared. Major anthocyanins were identified as peonidin or cyanidin 3-sophoroside-5-glucoside and their acylated derivatives, e.g., peonidin 3-sophoroside-5-glucoside, peonidin 3-(6''-p-feruloylsophoroside)-5-glucoside, and cyanidin 3-(6''-p-feruloylsophoroside)-5-glucoside, and main hydroxycinnamic acid derivatives were identified as mono- and dicaffeoylquinic acids (e.g., 5-O-caffeoylquinic acid and 3,5-di-O-caffeoylquinic acid) and caffeoyl-hexoside. These main phenolic compounds identified were important contributors to the total antioxidant capacity of the tested sweetpotato samples. Additionally, great variations in contents of both total and individual phenolic compounds as well as antioxidant activities between different genotypes and among various parts of the roots were observed. This study may provide value information for breeding new lines of Chinese purple-fleshed sweetpotato and also for quality control of bioactive components during production and processing.

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Sweetpotato starch is high‐yielding, but has limited development and uses. In this study, physicochemical properties of sweetpotato starch from 11 representative genotypes with diverse geographic origins in China were characterized and showed wide variations. Apparent amylose contents measured by iodine binding ranged from 23.3 to 26.5%, by gel permeation chromatography after debranching from 17.5 to 23.9%, and true amylose content by concanavalin A binding from 15.9 to 22.5%. In vitro digestibility varied from 29.5 to 41.2%. Swelling power and water solubility index were highly correlated (r2 = 0.88). Gelatinization peak temperature and enthalpy ranged from 75.4 to 79.7°C, and 7.6 to 13.6 J/g, respectively. Pasting peak and cold paste viscosities varied from 268 to 469 RVU, and 170 to 284 RVU. Amylose contents were highly correlated to digestibility, pasting, and thermal parameters.

Sweet potato, Ipomoea batatas (L.) Lam., is an important food crop that is cultivated worldwide. However, no genome-wide assessment of the genetic diversity of sweet potato has been reported to date. In the present study, the population structure and genetic diversity of 197 sweet potato accessions most of which were from China were assessed using 62,363 SNPs. A model-based structure analysis divided the accessions into three groups: group 1, group 2 and group 3. The genetic relationships among the accessions were evaluated using a phylogenetic tree, which clustered all the accessions into three major groups. A principal component analysis (PCA) showed that the accessions were distributed according to their population structure. The mean genetic distance among accessions ranged from 0.290 for group 1 to 0.311 for group 3, and the mean polymorphic information content (PIC) ranged from 0.232 for group 1 to 0.251 for group 3. The mean minor allele frequency (MAF) ranged from 0.207 for group 1 to 0.222 for group 3. Analysis of molecular variance (AMOVA) showed that the maximum diversity was within accessions (89.569%). Using CoreHunter software, a core set of 39 accessions was obtained, which accounted for approximately 19.8% of the total collection. The core germplasm set of sweet potato developed will be a valuable resource for future sweet potato improvement strategies.