First Report of Sweet Potato Virus E(SPVE) Infecting Sweet Potato in China

Sweet potato (Ipomoea batatas [L.] Lam.) is a versatile crop, cultivated in the subtropical and tropical areas, as food, fodder, and industrial raw material crop. In China, sweet potato has been used as a health-care food in recent years, as it contains a wide range of nutrients and xenobiotic phytochemicals. However, viral diseases are major constraint for the sweet potato yield and quality, especially the seed production and quality. Over 30 species of viruses infect sweet potato worldwide (Clark et al. 2012). More recently, a few new viruses infected sweet potato were identified, such as sweet potato virus E (SPVE), which was reported in Korea(Jo et al. 2020). In May 2022, a sweet potato sample (JSXZ1) with virus-like symptom, such as mosaic and vein clearing were collected from sweet potato germplasm Xuzhou resource nursery, Jiangsu Province, China (N34˚16', E117˚18') (Fig. S1A). To investigate the virus disease, the sample JSXZ1 showing the typical symptoms of disease was prepared for Small-RNA (sRNA) deep-sequencing. The sRNA library was constructed using TruSeq™ Small RNA Sample Prep Kits (Illumina, San Diego, USA) and sequenced using the Illumine Hiseq 2500 platform by LC-Bop Technologies (Hangzhou) CO., LTD. The sample was sequenced to obtain 26, 358, 439 raw reads and 22, 969, 139 clean reads after quality control trimming and analysis. The Velvet 1.0.5 software was used to de novo assemble the clean reads (18 to 28 nt) into larger contigs, which were then compared with the nucleotide sequences in the National Center for Biotechnology Information (NCBI) database using the BLASTn algorithm. Viruses found in the sample were sweet potato latent virus (SPLV), sweet potato feathery mottle virus (SPFMV), sweet potato chlorotic stunt virus (SPCSV), sweet potato badnavirus A (SPBV-A) and sweet potato badnavirus B (SPBV-B). Surprisingly, besides the viruses listed above, 28 contigs matched sequences of SPVE isolate GS (MH388502). To verify the result, total RNA was extracted from the sample JSXZ1 and from other leave samples (JSXZ2-JSXZ5) that contained SPFMV, SPVC, SPLV, SPVG respectively stored in lab using FastPure Universal Plant Total RNA Isolation Kit (Vazyme Biotech Co., LTD, Nanjing, China). cDNA was synthesized using random primer (hexadeoxyribonucleotide mixture; pd(N)6). The cDNA serves as template in PCR using a newly designed primer pairs based on SPVE p1 gene (SPVE-F: 5'- TCACCAAAAAGAATGCTACAAC-3'/SPVE-R: 5'-GAAATCCTCCCACTCTCCATA-3'). An expected ~500-bp PCR fragment was obtained in JSXZ1, while none of the fragment was obtained from JSXZ2-JSXZ5 (Fig. S1B). The PCR fragment was cloned into pMD18-T vector (Takara Bio Inc., Beijing, China) and plasmid DNA from transformed Escherichia coli DH5α cell (n=3) were commercially sequenced by Sangon Biotech (Shanghai) Co., Ltd. The sequences of the three fragment clones we obtained were 100% identical when compared. A BLASTN analysis of the sequences revealed that they are specific to SPVE and shared 98.62% nucleotide identity to SPVE GS isolate (MH388502) and one sequence was submitted to GenBank (Accession number OQ948331). To determine the occurrence of SPVE in infected sweet potato plants, a total of 37 leaves samples with viral symptom collected from Shandong Province (n=6) and Jiangsu Province (n=31) were indexed by RT-PCR as described before. Only 9 (24.3%) out of 37 from Shandong (n=1) and Jiangsu (n=8) were positive to SPVE respectively. In addition, five additional viruses (SPFMV, SPVC, SPVG, SPLV, SPCSV) were detected among these 37 samples and always in a mixed infection of two or more viruses. To our knowledge, this is the first report of SPVE infecting sweet potato in China. Sweet potato is an important crop in China and other countries (Zhang et al. 2023). China is the largest sweet potato producer all over the world. In addition, as sweet potato is produced through the vegetative propagation mode, thus, more attention should be paid to detection and monitoring of occurrence of SPVE in China.

The APSES transcription factor CfSwi6 is required for growth, cell wall integrity, and pathogenicity of Ceratocystis fimbriata

Cell wall integrity (CWI) is crucial for the growth, development, and host invasion of pathogenic fungi. The APSES transcription factor Swi6 in fungi plays a role in mediating cell wall integrity through the mitogen-activated protein kinase (MAPK) signaling pathway. Ceratocystis fimbriata is a notorious pathogenic fungus responsible for causing black rot in sweet potatoes. In this study, an orthologous APSES transcription factor Swi6 (CfSwi6) downstream of the CWI regulatory pathway in C. fimbriata was characterized. Deletion of CfSWI6 leads to impaired hyphal development, conidiation, and compromised cell wall integrity, resulting in a significant reduction in virulence. Transcriptome analysis revealed the involvement of CfSWI6 in various pathways, including the MAPK pathway, DNA synthesis and stress response. ChIP-seq data provided predictions of potential target genes regulated by CfSwi6. Through yeast one-hybrid, we confirmed the direct binding of CfSwi6 to the promoter of the chitin synthetase gene. In summary, these findings indicated that CfSwi6 plays an important role in the growth, development, and pathogenicity of C. fimbriata. This study provides new insights into the pathogenic mechanism of C. fimbriata in sweet potato and inspires potential strategies to control sweet potato black rot.

Invertase-producing bacteria and the sweetness content dataset of Cilembu sweet potatoes (Ipomoea batatas (L.) Lam.) grown in various agroecosystems

Cilembu sweet potato is one of Indonesia's leading agricultural commodities. The high carbohydrate content in sweet potatoes has the potential to change into sugar (glucose, sucrose, and fructose) during storage. The level of sweetness is one of the characteristics that determines the quality of sweet potatoes. The sweetness level of sweet potatoes is influenced by various factors, including genetics, environment, and their interactions. Apart from that, the role of invertase-producing bacteria in breaking down carbohydrates into sugars is very important. Information regarding the number of invertase-producing bacteria in Cilembu sweet potatoes and their activity during storage is still limited. This research aimed to determine the number and activity of invertase-producing bacteria in Cilembu sweet potatoes and estimate the relationship between activity and total invertase-producing bacteria during storage of Cilembu sweet potatoes. The results showed significant differences between the number and activity of invertase-producing bacteria at each storage time. There is a relationship between sugar levels and invertase-producing bacteria. Sucrose levels had a negative and significant correlation with fructose levels (-0.56) and invertase-producing bacteria (-0.58). Glucose levels were significantly and positively correlated with fructose levels (0.91) and invertase-producing bacteria (0.88). Fructose levels also significantly and positively correlated with invertase-producing bacteria (0.95). This information can be used as a reference in determining the quality of sweet potatoes directly and indirectly.

Baked sweetpotato textures and sweetness: An investigation into relationships between physicochemical and cooked attributes

Sweetpotato varieties vary greatly in perceived textures and sweetness. This study identified physicochemical factors that influence these attributes in cooked sweetpotatoes. Fifteen genotypes grown on three plots were baked and evaluated by a trained descriptive sensory analysis panel for sweetness and 13 texture attributes. Mechanical parameters were measured by texture profile analysis (TPA); and composition (starch, cell wall material, sugar contents), starch properties (thermal, granule type ratios, granule sizes), and amylase activities were characterized. TPA predicted fracturability and firmness well, whereas starch and sugar contents, B-type starch granule ratio, and amylase activities influenced prediction of mouthfeel textures. Sweetness perception was influenced by perceived particle size and sugar contents; and maltose generation during baking was highly correlated with raw sweetpotato starch content. These relationships between physicochemical sweetpotato properties and baked textures and sweetness could benefit breeders and processors in selecting biochemical traits that result in consumer preferred products.

Salicylic acid and jasmonic acid biosynthetic pathways are simultaneously activated in transgenic Arabidopsis expressing the rolB/C gene from Ipomoea batatas

The Agrobacterium rhizogenes root oncogenic locus (rol) genes interfere with hormone balance by altering their synthesis and/or recognition, giving rise to varied impacts on the physiological characteristics of plants and cell cultures. The homolog of the rolB and rolC genes from Ipomoea batatas, named Ib-rolB/C, similarly induces morphological and physiological alterations in transgenic Arabidopsis thaliana; however, its role in plant hormonal homeostasis has not been previously defined. In this study, we found that external application of salicylic acid (SA) and methyl jasmonate (MeJA) significantly upregulated Ib-rolB/C in detached I. batatas leaves. Furthermore, heterologous expression of Ib-rolB/C in A. thaliana markedly enhanced the accumulation of SA and MeJA, and to a lesser extent, elevated abscisic acid (ABA) levels, through the modulation of genes specific to hormone biosynthesis. Even though the RolB/RolC homolog protein has a notable structural resemblance to the RolB protein from A. rhizogenes, it exhibits a distinct localization pattern, predominantly residing in the cytoplasm and certain discrete subcellular structures, instead of the nucleus. Consequently, the functions of RolB/RolC in both naturally and artificially transgenic plants are linked to changes in the hormonal state of the cells, though the underlying signaling pathways remain to be elucidated.

Fast quantitative analysis and chemical visualization of amylopectin and amylose in sweet potatoes via merging 1D spectra and 2D image

The quantitative analysis and spatial chemical visualization of amylopectin and amylose in different varieties of sweet potatoes were studied by merging spectral and image information. Three-dimensional (3D) hyperspectral images carrying 1D spectra and 2D images of hundreds of the samples (amylopectin, n = 644; amylose, n = 665) in near-infrared (NIR) range of 950-1650 nm (426 wavelengths) were acquired. The NIR spectra were mined to correlate with the values of the two indexes using a linear algorithm, generating a best performance with correlation coefficients and root mean square error of prediction (rP and RMSEP) of 0.983 and 0.847 g/100 mg for amylopectin, and 0.975 and 0.500 g/100 mg for amylose, respectively. Then, 14 % of the wavelengths (60 for amylopectin, 61 for amylopectin) were selected to simplify the prediction with rP and RMSEP of 0.970 and 1.103 g/100 mg for amylopectin, and 0.952 and 0.684 g/100 mg for amylose, respectively, comparable to those of full-wavelength models. By transferring the simplified model to original images, the color chemical maps were created and the differences of the two indexes in spatial distribution were visualized. The integration of NIR spectra and 2D image could be used for the more comprehensive evaluation of amylopectin and amylose concentrations in sweet potatoes.

Genome-wide identification and expression analyses of CYP450 genes in sweet potato (Ipomoea batatas L.)

BACKGROUND

Cytochrome P450 monooxygenases (CYP450s) play a crucial role in various biochemical reactions involved in the synthesis of antioxidants, pigments, structural polymers, and defense-related compounds in plants. As sweet potato (Ipomoea batatas L.) holds significant economic importance, a comprehensive analysis of CYP450 genes in this plant species can offer valuable insights into the evolutionary relationships and functional characteristics of these genes.

RESULTS

In this study, we successfully identified and categorized 95 CYP450 genes from the sweet potato genome into 5 families and 31 subfamilies. The predicted subcellular localization results indicate that CYP450s are distributed in the cell membrane system. The promoter region of the IbCYP450 genes contains various cis-acting elements related to plant hormones and stress responses. In addition, ten conserved motifs (Motif1-Motif10) have been identified in the IbCYP450 family proteins, with 5 genes lacking introns and only one exon. We observed extensive duplication events within the CYP450 gene family, which may account for its expansion. The gene duplication analysis results showed the presence of 15 pairs of genes with tandem repeats. Interaction network analysis reveals that IbCYP450 families can interact with multiple target genes and there are protein-protein interactions within the family. Transcription factor interaction analysis suggests that IbCYP450 families interact with multiple transcription factors. Furthermore, gene expression analysis revealed tissue-specific expression patterns of CYP450 genes in sweet potatoes, as well as their response to abiotic stress and plant hormones. Notably, quantitative real-time polymerase chain reaction (qRT‒PCR) analysis indicated the involvement of CYP450 genes in the defense response against nonbiological stresses in sweet potatoes.

CONCLUSIONS

These findings provide a foundation for further investigations aiming to elucidate the biological functions of CYP450 genes in sweet potatoes.

Genome-wide identification, characterization, and expression analysis of the sweet potato (Ipomoea batatas [L.] Lam.) ARF, Aux/IAA, GH3, and SAUR gene families

BACKGROUND

Auxins are known to have roles in the tuberization process in sweet potato (Ipomoea batatas [L.] Lam.) and these effects are mediated by various auxin signalling gene families. In this study, an analysis of the sweet potato genome was performed to identify the ARF, Aux/IAA, GH3, and SAUR auxin signalling gene family members in this crop.

RESULTS

A total of 29 ARF, 39 Aux/IAA, 13 GH3, and 200 SAUR sequences were obtained, and their biochemical properties and gene expression profiles were analysed. The sequences were relatively conserved based on exon-intron structure, motif analysis, and phylogenetic tree construction. In silico expression analyses of the genes in fibrous and storage roots indicated that many sequences were not differentially expressed in tuberizing and non-tuberizing roots. However, some ARF, Aux/IAA, and SAUR genes were up-regulated in tuberizing storage roots compared to non-tuberizing fibrous roots while many GH3 genes were down-regulated. Additionally, these genes were expressed in a variety of plant parts, with some genes being highly expressed in shoots, leaves, and stems while others had higher expression in the roots. Some of these genes are up-regulated during the plant's response to various hormone treatments and abiotic stresses. Quantitative RT-PCR confirmation of gene expression was also conducted, and the results were concordant with the in silico analyses. A protein-protein interaction network was predicted for the differentially expressed genes, suggesting that these genes likely form part of a complex regulatory network that controls tuberization. These results confirm those of existing studies that show that auxin signalling genes have numerous roles in sweet potato growth and development.

CONCLUSION

This study provides useful information on the auxin signalling gene families in Ipomoea batatas and suggests putative candidates for further studies on the role of auxin signalling in tuberization and plant development.

Genotype-by-environment interactions (GEIs) and evaluate superior sweet potato (Ipomoea batatas [L.] Lam) using combined analysis and GGE biplot

Genetic studies on yield and yield quality are becoming benchmarks for farmers and industry in selecting and developing varieties. Evaluations that combine various stability statistics can provide more accurate information to select the ideal genotype. This study aims to identify the effect of genotype by environment interactions (GEIs) for yield and yield quality, to select high yield and stable sweet potato genotypes, as well as to select superior genotypes based on yield and yield quality. Three different environments in West Java, Indonesia, were used to test the sweet potato genotypes using a randomized block design that was repeated three times. Highly significant effects of sweet potato genotypes (G), environments (E), and GEIs were observed for yield and yield quality. The Combined ANOVA showed that GEIs effect contributed 54.88% for yield, 40.01% for sweetness, 10.46% for moisture content, 68.80% for tuber diameter, and 72.57% for tuber length from the sum of square. Five most high and stable yield on sweet potato genotypes identified by all measures, includes G4, G6, G7, G31, and G32. Genotype by yield*traits (GYT) selected seven genotypes that have superior in yield and yield quality, they were G7, G15, G4, G20, G6, G31, and G14. Based on stability measurements and GYT biplots, the genotypes G4, G6, G7, and G31 are in both slices. So that the four genotypes have high, stable yields, and have a good combination of traits for yield quality. Our findings can be used for improvement cultivation involving partner companies, partner institutions, and farmers, and the selected genotypes can be release as superior varieties candidate.

IbInvInh2, a novel invertase inhibitor in sweet potato, regulates starch content through post-translational regulation of vacuolar invertase IbβFRUCT2

As a key enzyme in the starch and sugar metabolic pathways in sweet potato (Ipomoea batatas (L.) Lam.), the vacuolar invertase (EC 3.2.1.26) IbβFRUCT2 is involved in partitioning and modulating the starch and sugar components of the storage root. However, the post-translational regulation of its invertase activity remains unclear. In this study, we identified three invertase inhibitors, IbInvInh1, IbInvInh2, and IbInvInh3, as potential interaction partners of IbβFRUCT2. All were found to act as vacuolar invertase inhibitors (VIFs) and belonged to the plant invertase/pectin methyl esterase inhibitor superfamily. Among the three VIFs, IbInvInh2 is a novel VIF in sweet potato and was confirmed to be an inhibitor of IbβFRUCT2. The N-terminal domain of IbβFRUCT2 and the Thr39 and Leu198 sites of IbInvInh2 were predicted to be engaged in their interactions. The transgenic expression of IbInvInh2 in Arabidopsis thaliana plants reduced the starch content of leaves, while its expression in the Ibβfruct2-expressing Arabidopsis plants increased the starch content of leaves, suggesting that the post-translational inhibition of IbβFRUCT2 activity by IbInvInh2 contributes to the regulation of the plant starch content. Taken together, our findings reveal a novel VIF in sweet potato and provide insights into the potential regulatory roles of the VIFs and invertase-VIF interaction in starch metabolism. These insights lay the foundation for using VIFs to improve the starch properties of crops.

Comparative elucidation on the phenolic fingerprint, sugars and antioxidant activity of white, orange and purple-fleshed sweet potatoes (Ipomoea batatas L.) as affected by different cooking methods

In this study, three cooking methods (baking, boiling, sous vide (SV)) were applied to Turkish sweet potatoes with three flesh colors (white, orange, purple) to examine the effects of the product color and cooking methods on the total phenolics, antioxidant activity, sugars, phenolic acids, and anthocyanins. LC-MS-MS was employed in the characterization of these compounds. It was observed that the product color and cooking method significantly affected the concentrations of bioactive compounds like polyphenols. Both the highest total phenolic content (11.36 mg/g) and antioxidant activity (DPPH (50.3 μM TE/g) and ABTS (63.53 μM TE/g)) were determined in the purple sweet potato cooked with the SV method. 10 phenolic acids were quantified in all samples which were in the highest amounts in the orange colored samples followed by the purple samples. Baking resulted in the highest total phenolic acids in all samples. 13 anthocyanins were detected in the purple-colored samples, while the SV cooking best preserved the anthocyanins. In sum, purple sweet potatoes cooked by SV are recommended for higher phenolic contents, antioxidant capacity and anthocyanins.

Genetic fingerprint construction and genetic diversity analysis of sweet potato (Ipomoea batatas) germplasm resources

BACKGROUND

China is the largest producer of sweet potato in the world, accounting for 57.0% of the global output. Germplasm resources are the basis for promoting innovations in the seed industry and ensuring food security. Individual and accurate identification of sweet potato germplasm is an important part of conservation and efficient utilization.

RESULTS

In this study, nine pairs of simple sequence repeat molecular markers and 16 morphological markers were used to construct genetic fingerprints for sweet potato individual identification. Combined with basic information, typical phenotypic photographs, genotype peak graphs, and a two-dimensional code for detection and identification were generated. Finally, a genetic fingerprint database containing 1021 sweet potato germplasm resources in the "National Germplasm Guangzhou Sweet Potato Nursery Genebank in China" was constructed. Genetic diversity analysis of the 1021 sweet potato genotypes using the nine pairs of simple sequence repeat markers revealed a narrow genetic variation range of Chinese native sweet potato germplasm resources, and Chinese germplasm was close to that from Japan and the United States, far from that from the Philippines and Thailand, and the furthest from that from Peru. Sweet potato germplasm resources from Peru had the richest genetic diversity, supporting the view that Peru is the center of origin and domestication of sweet potato varieties.

CONCLUSIONS

Overall, this study provides scientific guidance for the conservation, identification, and utilization of sweet potato germplasm resources and offers a reference to facilitate the discovery of important genes to boost sweet potato breeding.

Towards rapidly quantifying and visualizing starch content of sweet potato [Ipomoea batatas (L.) Lam] based on NIR spectral and image data fusion

This study aimed to achieve the rapid quantification and visualization of the starch content in sweet potato via near-infrared (NIR) spectral and image data fusion. The hyperspectral images of the sweet potato samples containing 900-1700 nm spectral information within every pixel were collected. The spectra were preprocessed, analyzed and the 18 informative wavelengths were finally extracted to relate to the measured starch content using the multiple linear regression (MLR) algorithm, producing a good quantitative prediction accuracy with a correlation coefficient of prediction (rP) of 0.970 and a root-mean-square error of prediction (RMSEP) of 0.874 g/100 g by an external validation using a set of dependent samples. The MLR model was further verified in terms of soundness and predictive validity via F-test and t-test, and then transferred to each pixel of the original two dimensional images with the help of a developed algorithm, generating color distribution maps to achieve the vivid visualization of the starch distribution. The study demonstrated that the fusion of the NIR spectral and image data provided a good strategy for the rapidly and nondestructively monitoring the starch content of sweet potato. This technique can be applied to industrial use in the future.

Yield performance and trait correlation of BARI released sweet potato varieties studied under several districts of Bangladesh

A study was carried out in five sweet potato growing regions of Bangladesh, each characterized by suitable agro-ecologies, in order to demonstrate the most favorable varietal performance and trait correlations. A completely randomized block design with three replications was used to compare the varietal performance of BARI (Bangladesh Agricultural Research Institute) released sweet potato varieties (viz. BARI Mistialu-9, BARI Mistialu-10, BARI Mistialu-12, BARI Mistialu-15 and BARI Mistialu-17). During the 2021-22 cropping season, sweet potato varieties were tested in five districts of Bangladesh, namely Gazipur, Bogura, Jamalpur, Jashore, and Chattogram. The findings revealed that the BARI Mistialu-12 variety exhibited remarkable attributes, including a high marketable storage root yield of 39.88 t/ha. Additionally, it demonstrated exceptional performance in various yield components such as vine length, average storage root weight, and dry weight of the root. Furthermore, a positive correlation was observed between several traits and yield, as well as yield-attributing characteristics. This correlation suggests that enhancing these traits could potentially contribute to an overall increase in the storage root yield of sweet potatoes.

Effects of annealing temperature and time on the structural and physicochemical properties of sweet potato flour hydrogels

The physicochemical properties of sweet potato flour (SPF) can be modified by annealing. Native SPF was annealed in deionized water at a flour-to-water ratio of 1:3 (w/v) and temperatures of 50, 55, 60, or 65 °C for either 12 or 24 h. Annealed SPF maintained the A-type crystalline region and displayed increased relative crystallinity, increased pasting temperature, and decreased breakdown. SPF gels showed enhanced hardness together with better springiness when SPF was annealed at low temperature/long time or high temperature/short time. Annealed SPF hydrogel sheets contained larger, more uniform, and smoother pores than native ones. Noticeably, hydrogel sheets made of SPF annealed at 50 °C for 24 h exhibited advanced fracture strain from 93% to 176%. Overall, this work showed that annealing could modulate the characteristics of SPR hydrogels, which may widen the extent of applications in food industries. However, the annealing conditions need to be optimized.

Simultaneous quantifying and visualizing moisture, ash and protein distribution in sweet potato [Ipomoea batatas (L.) Lam] by NIR hyperspectral imaging

This study aimed to achieve the rapid evaluation of moisture, ash and protein of sweet potato simultaneously by near-infrared (NIR) hyperspectral imaging (900-1700 nm). Hyperspectral images of 300 samples for each parameter were acquired and the spectra within images were extracted, averaged and preprocessed to relate to the three measured parameters, using partial least squares (PLS) algorithm, respectively, resulting in good performances. Nine, eleven and eleven informative wavelengths were selected to accelerate the prediction of the three parameters, generating a correlation coefficient of prediction (r _P) of 0.984, 0.905, 0.935 and root mean square error of prediction (RMSE_P) of 0.907%, 0.138%, 0.0941% for moisture, ash and protein, respectively. By transferring the best optimized PLS models to generate color chemical maps, the distributions and variations of the three parameters were visualized. NIR hyperspectral imaging is promising and can be applied to simultaneously evaluate multiple quality parameters of sweet potato.

Sweet potato ADP-glucose pyrophosphorylase small subunit affects vegetative growth, starch content and storage root yield

The development of storage roots is a key factor determining the yields of crop plants, including sweet potato. Here, using combined bioinformatic and genomic approaches, we identified a sweet potato yield-related gene, ADP-glucose pyrophosphorylase (AGP) small subunit (IbAPS). We found that IbAPS positively affects AGP activity, transitory starch biosynthesis, leaf development, chlorophyll metabolism, and photosynthesis, ultimately affecting the source strength. IbAPS overexpression in sweet potato led to increased vegetative biomass and storage root yield. RNAi of IbAPS resulted in reduced vegetative biomass, accompanied with a slender stature and stunted root development. In addition to the effects on root starch metabolism, we found that IbAPS affects other storage root development-associated events, including lignification, cell expansion, transcriptional regulation, and production of the storage protein sporamins. A combinatorial analysis based on transcriptomes, as well as morphological and physiological data, revealed that IbAPS affects several pathways that determine development of vegetative tissues and storage roots. Our work establishes an important role of IbAPS in concurrent control of carbohydrate metabolism, plant growth, and storage root yield. We showed that upregulation of IbAPS results in superior sweet potato with increased green biomass, starch content, and storage root yield. The findings expand our understanding of the functions of AGP enzymes and advances our ability to increase the yield of sweet potato and, perhaps, other crop plants.

Inhibitory effect of cinnamaldehyde on Fusarium solani and its application in postharvest preservation of sweet potato

Root rot caused by Fusarium solani is one of major postharvest diseases limiting sweet potato production. Antifungal effect and possible mode of action of cinnamaldehyde (CA) against F. solani were investigated. CA concentration of 0.075 g/L inhibited conidial viability of F. solani. CA vapor of 0.3 g/L in air completely controlled the F. solani development in sweet potatoes during storage for 10 days at 28 °C, and protected soluble sugar and starch in the flesh from depletion by the fungus. Further results demonstrated that CA induced reduction in mitochondrial membrane potential (Δψ_m), ROS accumulation, and cell apoptosis characterized by DNA fragmentation in F. solani. Moreover, CA facilitated decomposition of mitochondria-specific cardiolipin (CL) into its catabolites by the catalytic action of phospholipases. Altogether, the results revealed a specific antifungal mechanism of CA against F. solani, and suggest that CA holds promise as a preservative for postharvest preservation of sweet potato.

Identification and functional characterization of the SUMO system in sweet potato under salt and drought stress

Sumoylation is a crucial post-translation modification (PTM) that is the covalent attachment of SUMO molecules to the substrate catalyzed by enzyme cascade. Sumoylation is essential in almost every physiological process of plants, particularly in response to abiotic stress. However, little is known about sumoylation in sweet potato (Ipomoea batatas), the world's seventh most important food crop. In this study, 17 sweet potato SUMO system genes have been cloned and functionally characterized. Multiple sequence alignment and phylogenetic analysis showed sweet potato SUMO system proteins had conserved domains and activity sites. IbSUMOs, IbSAE1, and IbSCE1 were localized in the cytoplasm and nucleus. E3 SUMO ligases showed nuclear or punctate localization. In vitro sumoylation assay confirmed the catalytic activity of sweet potato SUMO system components. Heterologous expression of IbSIZ1 genes in Arabidopsis atsiz1 mutant rescued the defective germination and growth phenotype. IbSCE1a/b and IbSIZ1a/b/c were salt and drought responsive genes. Heterologous expression of IbSCE1a/b/c improved the drought tolerance of Arabidopsis thaliana, while IbSIZ1a/b/c significantly enhanced the salt and drought tolerance. Our findings define that the SUMO system in sweet potato shared with conserved function but also possessed specific characterization. The resources presented here would facilitate uncovering the significance of sumoylation in sweet potato.

Effects of intake of four types of snack with different timings on postprandial glucose levels after dinner

PURPOSE

It has been reported that the consumption of fruit granola (FG), mulberry leaves, and barley cookies as an afternoon snack suppresses the postprandial increase in glucose levels at dinner. However, there have been no reports on the second-meal effect of snacking on popular snacks, such as potato chips (PC), roasted sweet potato (SP), and black beans (BB), or on the interval between snacking and dinner.

METHOD

The present study was an open-label randomized crossover trial of five study groups (PC, SP, BB, FG, and no snack) regarding the second-meal effects with different intervals between snacks and dinner. The subjects consumed prescribed meals for lunch and dinner at 12:00 and 19:00, and a snack fixed at 838 kJ (= 200 kcal) at 15:00 or 17:00.

RESULTS

When the participants snacked at 15:00, the postprandial glucose elevation at dinner was suppressed in the FG and SP groups, and the area under the curve (AUC) was also low. When they snacked at 17:00, the postprandial glucose elevation was suppressed in all the groups. The AUCs for PC, FG, and SP were lower than those for no snacking. On the other hand, carbohydrate intake increased with snacking, but the total AUC of snacks and dinner did not differ in any of the groups. The duration of hyperglycemia decreased with snack intake, as did the glucose amplitude.

CONCLUSION

We believe that the intake of carbohydrates and soluble fiber in snacks is an important factor in the second-meal effect at dinner. These results will contribute to the development of snacking and research into the second-meal effect.

Genetic diversity assessment and genome-wide association study reveal candidate genes associated with component traits in sweet potato (Ipomoea batatas (L.) Lam)

The Korean sweet potatoes were bred by various cultivars introduced from Japanese, American, Porto Rico, China, and Burundi. This issue enriched their genetic diversity but also resulted in a mixture of cultivars. For genotyping, we collected and sequenced 66 sweet potato germplasms from different localities around Korea, including 36 modern cultivars, 5 local cultivars, and 25 foreign cultivars. This identified 447.6 million trimmed reads and 324.8 million mapping reads and provided 39,424 single nucleotide polymorphisms (SNPs) markers. Phylogenetic clustering and population structure analysis distinctly classified these germplasms into 5 genetic groups, group 1, group 2, group 3, group 4, and group 5, containing 20, 15, 10, 7, and 14 accessions, respectively. Sixty-three significant SNPs were selected by genome-wide association for sugar composition-related traits (fructose, glucose, and total sugars), total starch, amylose content, and total carotenoid of the storage root. A total of 37 candidate genes encompassing these significant SNPs were identified, among which, 7 genes were annotated to involve in sugar and starch metabolism, including galactose metabolism (itf04g30630), starch and sucrose metabolism (itf03g13270, itf15g09320), carbohydrate metabolism (itf14g10250), carbohydrate and amino acid metabolism (itf12g19270), and amino sugar and nucleotide sugar metabolism (itf03g21950, itf15g04880). This results indicated that sugar and starch are important characteristics to determine the genetic diversity of sweet potatoes. These findings not only illustrate the importance of component traits to genotyping sweet potatoes but also explain an important reason resulting in genetic diversity of sweet potato.

Effect of potassium intake on cadmium transporters and root cell wall biosynthesis in sweet potato

Large areas of farmland soil in southern China are deficient in potassium (K) and are contaminated with cadmium (Cd). Previously, we suggested that the K supplementation could reduce Cd accumulation in sweet potatoes (Ipomoea batatas (L.) Lam). In the present study, we investigated the underlying physiological and molecular mechanisms. A hydroponic experiment with different K and Cd treatments was performed to compare the transcriptome profile and the cell wall structure in the roots of sweet potato using RNA sequencing, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The results showed that K supply inhibits the expressions of IRT1 and YSL3, which are responsible for root Cd uptake under Cd exposure. Furthermore, the expressions of COPT5 and Nramp3 were downregulated by K, which increased Cd retention in the root vacuoles. The upregulation of POD, CAD, INT1 and SUS by K contributed to lignin and cellulose biosynthesis and thickening of root xylem cell wall, which further reduced Cd translocation to the shoot. In addition, K affected the expressions of LHT, ACS, TPS and TPP associated with the production of ethylene and trehalose, which involved in plant resistance to Cd toxicity. In general, K application could decrease the uptake and translocation of Cd in sweet potatoes by regulating the expression of genes associated with Cd transporters and root cell wall components.

Resistant starch from sweet potatoes: Recent advancements and applications in the food sector

In tropical and subtropical areas, tuber and root crops are staple foods and a key source of energy. Sweet potato (SP) is currently regarded as one of the world's top ten foods because of its diverse sizes, shapes, color, and health benefits. The resistant starch (RS) content of SP is substantial. It is predicted to become the cheapest item in the food industry due to its extensive variety, food stability, emulsifier and fat substitution capabilities, and as filler. As a result, interest in SP-sourced RS has recently increased. Due to their unique nutritional and functional qualities, novelty has become a popular research focus in recent years. This review will summarize the current understanding of SP starch components and their impact on the technological and physicochemical properties of produced starch for commercial viability. The importance of sweet potato RS in addressing future RS demand sustainability is emphasized. SPs are a viable alternative to tubers as a sustainable raw material for RS production. It has an advantage over tubers because of its intrinsic nutritional value and climatic endurance. Thermal, chemical, and enzymatic treatments are effective RS manufacturing procedures. The adaptability of sweet potato RS allows for a wide range of food applications.

Antiulcerative potential of sweet potato (Ipomoea batatas) against aspirin-induced gastric ulcers in a rabbit model

OBJECTIVES

Sweet potato (Ipomoea batatas) is accredited as a functional food because of its nutraceutical compounds. These dietary components may help heal lesions and ulcer scars in the stomach. This research was designed to examine the antioxidant and antiulcerative potential of sweet potato (red skin, white flesh) against aspirin-induced gastric ulcers in a rabbit model.

METHODS

Sweet potato samples were analyzed for in vitro analysis, such as 2,2-diphenyl-1-picrylhydrazyl assay, total phenolic content, and total flavonoid content. In a bioefficacy study, rabbits were divided into five groups (n = 6) in which G0 received the standard diet only, G1 150 mg/kg aspirin, G2 20 mg/kg omeprazole, G3 1000 mg/kg aqueous extract of sweet potato, and G4 1000 mg/kg ethanolic extract of sweet potato. After completion of the trial, the animals were decapitated and examined for antiulcer parameters, serum analysis, and hematologic parameters.

RESULTS

The mean values for 2,2-diphenyl-1-picrylhydrazyl, total phenolic content, and total flavonoid content were 57%, 927 mg gallic acid equivalent/100 g, and 1901 µg quercetin equivalent/g, respectively. The values for gastric volume, acid output, ulcer scores and index, total oxidant status, white blood cell count, and lymphocyte count were increased significantly (P < 0.05) for the positive control group compared with G2, G3, and G4. Gastric pH and body weight at the end of the experiment were significantly reduced for the positive control group (P < 0.05) compared with G2, G3, and G4. Histology test results of gastric tissues in G1 depicted severe epithelial damage compared with G2, G3, and G4.

CONCLUSIONS

The results for the antiulcer parameters ascertained the antiulcer activity of sweet potato in aspirin-induced gastric ulcer models.

Changes in carbon allocation and subplastidal amyloplast structures of specialised Ipomoea batatas (sweet potato) storage root phenotypes

Vitamin A deficiency (VAD) in Low and Medium Income countries remains a major health concern. Ipomoea batatas, orange sweet potato (OSP), is one of the biofortification solutions being implemented by the World Health Organisation (WHO) to combat VAD. However, high provitamin A (β-carotene) content has been associated with a reduction in dry matter, reducing calorific value and having adverse effects on consumer traits. Both starch and carotenoid formation are located in amyloplasts and could potentially compete for the same precursors. Hence, five different sweet potato storage root phenotypes were characterized through spatial metabolomics and proteomics at the sub-plastidal level. The metabolite data suggested an indirect correlation of starch and carotenoids through the TCA cycle and pentose phosphate pathway. Furthermore, a change in lipid composition was observed to accommodate the storage of carotenoids in the hydrophilic environment of the amyloplast. The data suggests an alteration of cellular ultra-structures and perturbation of metabolism in high β-carotene producing sweet potato roots. This corroborates with previous gene expression analysis through biochemical analysis of sweet potato root tissue.

Production and characterization of a novel interspecific somatic hybrid combining drought tolerance and high quality of sweet potato and Ipomoea triloba L

A novel interspecific somatic hybrid combining drought tolerance and high quality of sweet potato and Ipomoea triloba L. was obtained and its genetic and epigenetic variations were studied. Somatic hybridization can be used to overcome the cross-incompatibility between sweet potato (Ipomoea batatas (L.) Lam.) and its wild relatives and transfer useful and desirable genes from wild relatives to cultivated plants. However, most of the interspecific somatic hybrids obtained to date cannot produce storage roots and do not exhibit agronomic characters. In the present study, a novel interspecific somatic hybrid, named XT1, was obtained through protoplast fusion between sweet potato cv. Xushu 18 and its wild relative I. triloba. This somatic hybrid produced storage roots and exhibited significantly higher drought tolerance and quality compared with its cultivated parent Xushu 18. Transcriptome and real-time quantitative PCR (qRT-PCR) analyses revealed that the well-known drought stress-responsive genes in XT1 and I. triloba were significantly up-regulated under drought stress. The genomic structural reconstructions between the two genomes of the fusion parents in XT1 were confirmed using genomic in situ hybridization (GISH) and specific nuclear and cytoplasmic DNA markers. The DNA methylation variations were characterized by methylation-sensitive amplified polymorphism (MSAP). This study not only reveals the significance of somatic hybridization in the genetic improvement of sweet potato but also provides valuable materials and knowledge for further investigating the mechanism of storage root formation in sweet potato.

Evaluation of released sweet potato [Ipomoea batatas (L.) Lam] varieties for yield and yield-related attributes in Semen-Bench district of Bench-Sheko-Zone, South-Western Ethiopia

Sweet potato is a significant root crop that can be used for both food and feed. Bench-Sheko zone mid-altitudes, in general, are among the most important sweet potato growing regions in southwest Ethiopia. During the 2017 and 2018 growing seasons, a study was carried out in the Semen-Bench district of the Bench-sheko zone, southwestern Ethiopia, to investigate the adaptability and performance of improved sweet potato varieties and to identify the best performer variety. A randomized complete block design with three replications was used to compare the performance of five improved (viz., Awassa-83, Beletch, Berkume, Kulfo, Tula) and one Local sweet potato variety. The results of both years and over year combined statistical analysis indicated that the varieties significantly varied in terms of all yield and yield-related traits. As a result, the Awassa-83 variety acquired the greatest values of average root diameter in both the 2017 (11.9 cm) and 2018 (10.1 cm) growing seasons, followed by the Berkume variety. In both 2017 and 2018 growing seasons and over year combined analysis, the highest average storage root length (21.5 cm), marketable storage root yield (29.06 ton/ha), total storage root yield (43.22 ton/ha), and storage root dry weight (42%) was recorded from variety Awassa-83. Variety Beletech and Berkume were found to be statistically similar and the next highest in terms of marketable storage root yield, and total storage root yield; moreover, variety Berkume was found to be the next highest in terms of storage root dry weight in two years combined result. On the other hand, the variety Beletech, which was closely followed by Awassa-83, had the highest average number of roots per plant (8.28) and the greatest number of marketable roots per plant (7.04). Therefore, considering overall traits Awassa-83 was found to be superior in overall performance and can be recommended for production in the study area and related agro-ecologies.

Insights into sweet potato SR proteins: from evolution to species-specific expression and alternative splicing

SR proteins from sweet potato have conserved functional domains and similar gene structures as that of Arabidopsis and rice in general. However, expression patterns and alternative splicing regulations of SR genes from different species have changed under stresses. Novel alternative splicing regulations were found in sweet potato SR genes. Serine/arginine-rich (SR) proteins play important roles in plant development and stress response by regulating the pre-mRNA splicing process. However, SR proteins have not been identified so far from an important crop sweet potato. Through bioinformatics analysis, our study identified 24 SR proteins from sweet potato, with comprehensively analyzing of protein characteristics, gene structure, chromosome localization, and cis-acting elements in promotors. Salt, heat, and mimic drought stresses triggered extensive but different expressional regulations on sweet potato SR genes. Interestingly, heat stress caused the most active disturbances in both gene transcription and pre-mRNA alternative splicing (AS). Tissue and species-specific transcriptional and pre-mRNA AS regulations in response to stresses were found in sweet potato, in comparison with Arabidopsis and rice. Moreover, novel patterns of pre-mRNA alternative splicing were found in SR proteins from sweet potato. Our study provided an insight into similarities and differences of SR proteins in different plant species from gene sequences to gene structures and stress responses, indicating SR proteins may regulate their downstream genes differently between different species and tissues by varied transcriptional and pre-mRNA AS regulations.

Impact of polyethylene on soil physicochemical properties and characteristics of sweet potato growth and polyethylene absorption

Microplastic (MP) pollution problem is severe in China. As the main component of mulch film, whether polyethylene (PE) poses a threat to the safe production of sweet potato is unknown. In this study, micron-sized original or weathered PE was simulated as the field film particles, and pot, hydroponic experiment were conducted to explore the effects of original and weathered MPs on physicochemical properties in soil, growth and phosphorus (P), potassium (K) absorption in sweet potato; P and K adsorption in liquid environment, and also the distribution of original MPs in sweet potato tissues respectively. The results showed that 5 μm original PE MPs significantly reduced pH (5.6-7.9%) and increased EC (6.0-12.1%) of soil compared to weathered PE MPs. In addition, original PE MPs can also significantly improved the biomass growth rates (5.9-19.0%) of sweet potato compared with weathered PE MPs by adsorbing more Olsen-P and Olsen-K in soil, and increasing K concentration in stems compared with control (17.1-55.4%). Although there was no significant difference between original and weathered PE MPs on the degree of membrane lipid peroxidation in sweet potato leaves, the original PE MPs made sweet potato exhibit the stronger oxidative stress. The tissue distribution of PE MPs-fluorescent spheres were only observed in cortical tissues of roots and stems. Results from our study suggest that sweet potato were not significantly affected by a short term exposure to single PE MPs.

Sodium alginate/gum arabic/glycerol multicomponent edible films loaded with natamycin: Study on physicochemical, antibacterial, and sweet potatoes preservation properties

Sweet potato (Ipomonea batatas Lam) is easily damaged due to its thin skin, which is limited in shelf life and causes enormous economic losses in the food industry. A new type of safe, non-toxic, and edible antibacterial functional film was developed with sodium alginate (2.5 %), gum arabic (1 %), glycerol (2 %), and natamycin as an antimicrobial agent in this study. The physical and antibacterial properties of films, such as thickness, chromaticity, water vapor permeability, tensile strength, and elongation at break, were studied. Furthermore, the antibacterial film was applied in the preservation of sweet potatoes. The results showed that natamycin emulsion had good compatibility with sodium alginate. Besides reducing the transparency of the composite membrane, the mechanical properties, barrier properties, and thermal stability of the composite film were significantly enhanced by the addition of natamycin prepared by a pH-cycle method. When the concentration of natamycin in the membrane solution reached 40 μg/mL or more, the antibacterial film had a noticeable inhibitory effect on the growth of molds, and yeasts, significantly enhancing the bacteriostatic effect of the base film. During the sweet potatoes storage, the water content, total starch content, Vc content, and flavonoid glycoside content of sweet potato showed a downward trend. However, the treatment of antibacterial film containing natamycin could slow down the physiological and quality changes of sweet potatoes during conventional storage, and the sweet potatoes still had good processing quality after 120 days of storage.

Development of a dual RT-RPA detection for Sweet potato feathery mottle virus and Sweet potato chlorotic stuntvirus

The disease co-infected by Sweet potato feathery mottle virus (SPFMV) and Sweet potato chlorotic stunt virus (SPCSV) is devastating in sweet potato, as it would give rise to the serious losses in both production and quality. Consequently, it is conducive for preventing and controlling this disease to detect these two viruses accurately and timely. Here we developed and optimized a dual reverse transcription recombinase polymerase amplification (RT-RPA) for rapid and accurate detection of SPFMV and SPCSV. Four special primers were designed based on the conserved sequences of SPFMV and SPCSV, respectively. The sensitivity of dual RT-RPA for SPFMV and SPCSV was 10^-4 ng/μL at the optimal conditions in which the primer ratio between SPFMV and SPCSV was 2:1, and the reaction incubated for 25 min at a temperature of 39 °C. Both 61 sweet potato samples and 5 morning glory samples collected from China were tested using the dual RT-RPA successfully. Therefore, the dual RT-RPA is a reliable, rapid, sensitive method to detect these two viruses in sweet potato. It is the RT-RPA that was used for detection of SPFMV and SPCSV simultaneously firstly. This dual RT-RPA, as a convenient and powerful tool, will be useful to diagnose SPFMV and SPCSV.

Biology and biotechnological aspect of sweet potato (Ipomoea batatas L.): a commercially important tuber crop

This review highlights the economic importance of sweet potato and discusses new varieties, agronomic and cultivation practices, pest and disease control efforts, plant tissue culture protocols, and unexplored research areas involving this plant. Abstract Sweet potato is widely consumed in many countries around the world, including India, South Africa and China. Due to its valuable nutritional composition and highly beneficial bioactive compounds, sweet potato is considered a major tuber crop in India. Based on the volume of production, this plant ranks seventh in the world among all food crops. Sweet potato is considered a "Superfood" by the 'Centre for Science in the Public Interest' (CSPI), USA. This plant is mostly propagated through vegetative propagation using vine cuttings or tubers. However, this process is costly, labour-intensive, and comparatively slow. Conventional propagation methods are not able to supply sufficient disease-free planting materials to farmers to sustain steady tuber production. Therefore, there is an urgent need to use various biotechnological approaches, such as cell, tissue, and organ culture, for the large-scale production of healthy and disease-free planting material for commercial purposes throughout the year. In the last five decades, a number of tissue culture protocols have been developed for the production of in vitro plants through meristem culture, direct adventitious organogenesis, callus culture and somatic embryogenesis. Moreover, little research has been done on synthetic seed technology for the in vitro conservation and propagation of sweet potato. The current review comprehensively describes the biology, i.e., plant phenotypic description, vegetative growth, agronomy and cultivation, pests and diseases, varieties, and conventional methods of propagation, as well as biotechnological implementation, of this tuber crop. Furthermore, the explored and unexplored areas of research in sweet potato using biotechnological approaches have been reviewed.

Comparative full-length transcriptome analysis by Oxford Nanopore Technologies reveals genes involved in anthocyanin accumulation in storage roots of sweet potatoes (Ipomoea batatas L.)

Background

Storage roots of sweet potatoes (Ipomoea batatas L.) with different colors vary in anthocyanin content, indicating different economically agronomic trait. As the newest DNA/RNA sequencing technology, Oxford Nanopore Technologies (ONT) have been applied in rapid transcriptome sequencing for investigation of genes related to nutrient metabolism. At present, few reports concern full-length transcriptome analysis based on ONT for study on the molecular mechanism of anthocyanin accumulation leading to color change of tuberous roots of sweet potato cultivars.

Results

The storage roots of purple-fleshed sweet potato (PFSP) and white-fleshed sweet potato (WFSP) at different developmental stages were subjected to anthocyanin content comparison by UV-visible spectroscopy as well as transcriptome analysis at ONT MinION platform. UV-visible spectrophotometric measurements demonstrated the anthocyanin content of PFSP was much higher than that of WFSP. ONT RNA-Seq results showed each sample generated average 2.75 GB clean data with Full-Length Percentage (FL%) over 70% and the length of N50 ranged from 1,192 to 1,395 bp, indicating reliable data for transcriptome analysis. Subsequent analysis illustrated intron retention was the most prominent splicing event present in the resulting transcripts. As compared PFSP with WFSP at the relative developmental stages with the highest (PH vs. WH) and the lowest (PL vs. WL) anthocyanin content, 282 and 216 genes were up-regulated and two and 11 genes were down-regulated respectively. The differential expression genes involved in flavonoid biosynthesis pathway include CCoAOMT, PpLDOX, DFR, Cytochrome P450, CHI, and CHS. The genes encoding oxygenase superfamily were significantly up-regulated when compared PFSP with WFSP at the relative developmental stages.

Conclusions

Comparative full-length transcriptome analysis based on ONT serves as an effective approach to detect the differences in anthocyanin accumulation in the storage roots of different sweet potato cultivars at transcript level, with noting that some key genes can now be closely related to flavonoids biosynthesis. This study helps to improve understanding of molecular mechanism for anthocyanin accumulation in sweet potatoes and also provides a theoretical basis for high-quality sweet potato breeding.

Transcriptomic analysis of tuberous root in two sweet potato varieties reveals the important genes and regulatory pathways in tuberous root development

Background

Tuberous root formation and development is a complex process in sweet potato, which is regulated by multiple genes and environmental factors. However, the regulatory mechanism of tuberous root development is unclear.

Results

In this study, the transcriptome of fibrous roots (R0) and tuberous roots in three developmental stages (Rl, R2, R3) were analyzed in two sweet potato varieties, GJS-8 and XGH. A total of 22,914 and 24,446 differentially expressed genes (DEGs) were identified in GJS-8 and XGH respectively, 15,920 differential genes were shared by GJS-8 and XGH. KEGG pathway enrichment analysis showed that the DEGs shared by GJS-8 and XGH were mainly involved in “plant hormone signal transduction” “starch and sucrose metabolism” and “MAPK signal transduction”. Trihelix transcription factor (Tai6.25300) was found to be closely related to tuberous root enlargement by the comprehensive analysis of these DEGs and weighted gene co-expression network analysis (WGCNA).

Conclusion

A hypothetical model of genetic regulatory network for tuberous root development of sweet potato is proposed, which emphasizes that some specific signal transduction pathways like “plant hormone signal transduction” “Ca²⁺signal” “MAPK signal transduction” and metabolic processes including “starch and sucrose metabolism” and “cell cycle and cell wall metabolism” are related to tuberous root development in sweet potato. These results provide new insights into the molecular mechanism of tuberous root development in sweet potato.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08670-x.

Effect of protein enrichment on quality characteristics and glycemic index of gluten free sweet potato (Ipomoea batatas L.) spaghetti

The aim of present investigation was justifying the suitability of sweet potato flour for development of gluten free spaghetti with reduced starch digestibility and to enhance protein content by fortification of whey protein concentrate (WPC) and chickpea flour (CPF) at the rate of 5%, 10%, and 15% respectively along with control. The effect of fortification in spaghetti was assessed for its glycemic index, physical, nutritional, and sensory properties. The data revealed that increase in the level of fortification of WPC and CPF resulted with increase in optimum cooking time, weight and volume without affecting cooking loss as compared to control sample. The percent increase in protein content of spaghetti fortified with WPC and CPF found as 192.20% and 150.08% respectively in comparison with control. However, spaghetti fortified with 15% CPF and 15% WPC showed lowest starch digestibility with reduced glycemic index to 59.43 and 58.73 respectively. The spaghetti fortified with 10% WPC and 10% CPF was found overall acceptable by panelists. Moreover, the fortification of spaghetti with WPC and CPF could significantly increase the protein content along with overall acceptability and functional characteristics.

Transcriptomic analyses of sweet potato in response to Cd exposure and protective effects of K on Cd-induced physiological alterations

We aimed to understand the molecular mechanism of differential cadmium (Cd) accumulation in two cultivars of sweet potato and to clarify the effects of potassium (K) supply on Cd accumulation. Comparative transcriptomes were employed to identify key genes and pathways using a low-Cd (N88) and a high-Cd cultivar (X16) in a pot experiment. The antioxidant capacity and cell wall components of root tips were analyzed to account for the effect of K regulating Cd accumulation in N88 via a hydroponic experiment. Transcriptome analysis revealed that 29 and 20 genes were differentially expressed in N88 and X16, respectively, when comparing the control with the two Cd treatments. X16 had more differentially expressed genes (DEGs), including 2649 common up-regulated and 3173 common down-regulated than N88 in any treatment. GO and KEGG analyses showed that the DEGs were assigned and enriched in different pathways. Some critical DEGs such as PDR, HMA3, COPT5, CAX3, GAUT, CCR, AUX1, CAT, SOD, GSR, and GST were identified. The DEGs were involved in pathways including heavy metal transport or detoxification, cell wall biosynthesis, plant hormone signal transduction, and glutathione metabolism. Additionally, K supply substantially decreased Cd accumulation and reactive oxygen species production and promoted the production of cellulose, pectin and lignin in the root tips when exposed to Cd. Several critical DEGs associated with heavy metal transport and cell wall biosynthesis were responsible for the difference of Cd accumulation between the two cultivars. Application of K could help decrease Cd accumulation in sweet potato.

A cytochrome P450 superfamily gene, IbCYP82D47, increases carotenoid contents in transgenic sweet potato

The cytochrome P450 superfamily (CYP450) is one of the largest protein families in plants, and its members play diverse roles in primary and secondary metabolic biosynthesis. In this study, the CYP450 family gene IbCYP82D47 was cloned from the high carotenoid line HVB-3 of sweet potato (Ipomoea batatas). The IbCYP82D47 protein harbored two transmembrane domains and dynamically localized between plastid stroma and membrane. Overexpression of IbCYP82D47 not only increased total carotenoid, lutein, zeaxanthin and violaxanthin contents by 32.2-48.0%, 10.5-13.3%, 40.2-136% and 82.4-106%, respectively, but also increased the number of carotenoid globules in sweet potato storage roots. Furthermore, genes associated with the carotenoid biosynthesis (IbDXS, IbPSY, IbLCYE, IbBCH, IbZEP) were upregulated in transgenic sweet potato. In addition, IbCYP82D47 physically interacts with geranylgeranyl diphosphate synthase 12 (IbGGPPS12). Our findings suggest that IbCYP82D47 increases carotenoid contents by interacting with the carotenoid biosynthesis related protein IbGGPPS12, and influencing the expressions of carotenoid biosynthesis related genes in transgenic sweet potato.

Genome-wide identification and characterization of F-box family proteins in sweet potato and its expression analysis under abiotic stress

In this study, genome-wide characterization of F-box proteins in sweet potato yielded 243 IbFBX genes, unevenly distributed on the 15 chromosomes of sweet potato. Gene duplication analysis suggested segmental duplication as the principal factor influencing the expansive evolution of IbFBX genes in sweet potato. Phylogenetic analysis clustered F-box proteins in sweet potato, Arabidopsis, and rice into six clades (I-VI). Gene structure analysis of the IbFBX genes revealed that most of the genes within the same clade were highly conserved. Expression profiles of IbFBX family genes in 9 different tissues and under stress conditions revealed that the IbFBXs were highly upregulated or downregulated in response to salt and drought stress, suggesting their significant roles in abiotic stress response and adaptation. Knowledge of the diverse functions and expression patterns of IbFBXs presents a solid theoretical basis for annotating the functions of IbFBXs and further facilitate the molecular breeding of sweet potato.

Isolation and functional characterization of a glucose-6-phosphate/phosphate translocator (IbG6PPT1) from sweet potato (Ipomoea batatas (L.) Lam.)

Sweet potato (Ipomoea batatas (L.) Lam.) is a good source of carbohydrates, an excellent raw material for starch-based industries, and a strong candidate for biofuel production due to its high starch content. However, the molecular basis of starch biosynthesis and accumulation in sweet potato is still insufficiently understood. Glucose-6-phosphate/phosphate translocators (GPTs) mediate the import of glucose-6-phosphate (Glc6P) into plastids for starch synthesis. Here, we report the isolation of a GPT-encoding gene, IbG6PPT1, from sweet potato and the identification of two additional IbG6PPT1 gene copies in the sweet potato genome. IbG6PPT1 encodes a chloroplast membrane-localized GPT belonging to the GPT1 group and highly expressed in storage root of sweet potato. Heterologous expression of IbG6PPT1 resulted in increased starch content in the leaves, root tips, and seeds and soluble sugar in seeds of Arabidopsis thaliana, but a reduction in soluble sugar in the leaves. These findings suggested that IbG6PPT1 might play a critical role in the distribution of carbon sources in source and sink and the accumulation of carbohydrates in storage tissues and would be a good candidate gene for controlling critical starch properties in sweet potato.

Sugar and ethanol production potential of sweet potato (Ipomoea batatas) as an alternative energy feedstock: processing and physicochemical characterizations

This study focuses on the processing, characterization, and sugar and ethanol production potential of red-fleshed sweet potatoes (RFSP) and white-fleshed sweet potatoes (WFSP). These feedstocks were used for the production of sugar; and bioethanol from its pulp by the action of five different microbes. The characterization of raw sweet potatoes and desired products of raw sugar, and bioethanol were carried out through proximate analyses, Fourier transforms infrared spectroscopic (FTIR) method, measurement of pol% by using a Refractometer, Polarimeter, Saccharimeter. The proximate analyses of feedstocks show the presence of a respectable amount of dry solids 25 ± 0.03g/100g with a lower amount of fat (0.025 ± 0.002) and ash (0.533 ± 0.076) contents make them promising crops for the production of sugar and ethanol. Comparatively, RFSP raw sugar (^oZ: 95.25 ± 0.05) is considered purer than WFSP raw sugar (^oZ: 94.6 ± 0.015). FTIR spectrums of the presently studied raw sugar and bioethanol have characteristic bands. It shows that the raw sugars products are rich in sucrose content, and confirms that the bioethanol was produced from the selected raw materials is at a satisfactory level. The efficiency of microbes was evaluated by taking a sample from the fermented wash to measure the residual sugar in (^oBrix). Comparatively, fermented wash with sweet potato extracted yeast was found 14% Brix^o (consume 86% of pulp) in RFSP, and 17% of Brix^o (consume 83% pulp) in WFSP within 24 hours of fermentation. The alcohol level of bioethanol's produced from RFSP and WFSP pulps was tested using Ebuliometer and the result was found to be ranged 78 °C – 80 °C which is closer to the boiling point of absolute anhydrous alcohol (78.3 °C). Thus, the results of the present study proved that the sweet potato and its pulp are considered as a potential alternative sugar/energy feedstock.

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Sweet potato is a cheaper sugar-containing crop and abundant resource.

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Red-fleshed sweet potato has greater sucrose content with higher purity (95.42 g/L).

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Industries can ease the production of sugar & bioethanol using sweet potato.

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Efficiency of studied inoculums is graded as: SPY > LEY > SCY > KEY > SRB.

Differential expression pattern of novel MADS-box genes in early root formation and differentiation of sweet potato

MADS-box genes are important transcription factors affecting overall development, but their role in sweet potato [Ipomoea batatas (L.) Lam.] has not been fully studied. This study isolated six novel MADS-box genes (IbSOC1, IbFUL1, IbAGL6, IbSVP1, IbSVP2, and IbSVP3) from sweet potato [Ipomoea batatas (L.) Lam. cv. Annouimo] during the early root differentiation stage using the de novo transcriptome assembly sequencing method. At the early root differentiation (between 0 and 3 days after transplanting), the IbSOC1, IbFUL1, and IbSVP2 genes decreased rapidly, whereas the IbSVP3 gene decreased gradually. In the early stages of root formation (0-30 days), the levels of IbSVP1 and IbSVP3 expression were steady, but the levels of IbSOC1 expression decreased gradually. The expression of six novel genes was also conducted in the tuberous root formation stage (30-90 days), and the IbSVP3 gene increased significantly according to the formation of the tuberous root. Six novel MADS-box genes that were believed to influence the entire root formation of sweet potato were isolated from the sweet potato. This study provides a genetic basis for further research on sweet potato root formation and development.

Genome-wide identification, phylogeny and expression analysis of AP2/ERF transcription factors family in sweet potato

Background

In recent years, much attention has been given to AP2/ERF transcription factors because they play indispensable roles in many biological processes, such as plant development and biotic and abiotic stress responses. Although AP2/ERFs have been thoroughly characterised in many plant species, the knowledge about this family in the sweet potato, which is a vital edible and medicinal crop, is still limited. In this study, a comprehensive genome-wide investigation was conducted to characterise the AP2/ERF gene family in the sweet potato.

Results

Here, 198 IbAP2/ERF transcription factors were obtained. Phylogenetic analysis classified the members of the IbAP2/ERF family into three groups, namely, ERF (172 members), AP2 (21 members) and RAV (5 members), which was consistent with the analysis of gene structure and conserved protein domains. The evolutionary characteristics of these IbAP2/ERF genes were systematically investigated by analysing chromosome location, conserved protein motifs and gene duplication events, indicating that the expansion of the IbAP2/ERF gene family may have been caused by tandem duplication. Furthermore, the analysis of cis-acting elements in IbAP2/ERF gene promoters implied that these genes may play crucial roles in plant growth, development and stress responses. Additionally, the available RNA-seq data and quantitative real-time PCR (qRT-PCR) were used to investigate the expression patterns of IbAP2/ERF genes during sweet potato root development as well as under multiple forms of abiotic stress, and we identified several developmental stage-specific and stress-responsive IbAP2/ERF genes. Furthermore, g59127 was differentially expressed under various stress conditions and was identified as a nuclear protein, which was in line with predicted subcellular localization results.

Conclusions

This study originally revealed the characteristics of the IbAP2/ERF superfamily and provides valuable resources for further evolutionary and functional investigations of IbAP2/ERF genes in the sweet potato.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-08043-w.

First report of sweet potato chlorotic stunt virus infecting sweet potatoes in Hungary

Sweet potato chlorotic stunt virus (SPCSV), a crinivirus in the family Closteroviridae, is a quarantine pest in Europe and one of the most economically important viruses of sweet potato (Ipomoea batatas (L.) Lam) crops globally. It forms synergies with other viruses in sweet potato, leading to yield loss of 30-100% (Qin et al., 2014). In summer 2020, 62 symptomatic and 38 symptomless sweet potato vines were randomly collected in farmers' fields in the south (Ásotthalom, Szeged) and central (Galgahévíz) parts of Hungary and transplanted in an insect-proof greenhouse. Six of the plants expressed SPCSV-like symptoms, including stunting, vein clearing and leaf purpling (Suppl1). To check for common viruses of sweet potato (Suppl2), total RNA and DNA were extracted from leaves of each of the 100 plants using Trizolate reagent (UD-GenoMed, Debrecen, Hungary) and Zenogene kit (Zenon Bio, Szeged, Hungary), respectively. Primer pair Ch2N (Suppl2) was designed using Primer3 (v. 0.4.0) to amplify a 194 bp fragment of SPCSV RNA1. Presence of the RNA viruses was checked by qPCR using qPCRBIO SyGreen 1-step qPCR kit (PCR Biosystems, London, UK), while DNA viruses were checked by PCR using DreamTaq DNA Polymerase (Thermo Scientific, Vilnius, Lithuania), followed by 1% agarose gel electrophoresis. Four samples (labelled A5.1, A6.1, A6V9-1, A6V9-2) out of the 100 tested positive for SPCSV. Two of them (A6V9-1 and A6V9-2) were co-infected with SPCSV, a badnavirus sweet potato pakakuy virus (SPPV) and a potyvirus sweet potato virus 2 (SPV2), while the other two (A5.1 and A6.1) lacked SPV2. Plants infected with SPCSV, SPV2 and SPPV displayed more severe symptoms. To confirm the results, cDNA synthesized from the four SPCSV positive samples using RevertAid first strand cDNA synthesis kit (Thermo Scientific, Vilnius, Lithuania) underwent PCR (94oC 4 min, 94oC 1 min, 53oC 30 s, 72oC 70 s and 72oC 10 min for a total of 30 cycles) using primers CL43U and CL43L for the viral heat shock protein 70 gene (Maliogka et al., 2020). An expected band size of 486 bp was obtained in all cases. The amplicon from sample A6.1 was sequenced and found to be identical to SPCSV Guatemalan isolate GT:B3:08 (acc. JF699628). RNA1 and RNA2 complete sequences from sample A6.1 were obtained via PCR amplifications of cDNA using primers (Suppl2) designed (from acc. KC888966 for RNA1 and acc. KC888963 for RNA2) to amplify overlapping fragments of West African strain of SPCSV. QIAquick gel extraction kit (QIAGEN, Hilden, Germany) was used to purify the PCR fragments, which were then cloned into pGEM-T Easy Vector (Promega, Madison, USA) and sequenced using Sanger sequencing technique (Biomi, Gödöllő, Hungary). BLASTn search revealed that RNA1 of our isolate Hun_01 (acc. MW892835) had 99.63% sequence identity to SPCSV isolate su-17-10 (acc. MK802073), while RNA2 of Hun_01 (acc. MW892836) was 99.68% similar to SPCSV isolate min-17-1 (acc. MK802078) and isolate 24-1 (acc. MK802080). Phylogenetic analysis using MegAlign (v. 7.1.0, 44.1) showed a close relationship between our isolate and those isolated in China, suggesting that they may have a common origin (Suppl1). Severe stunting and leaf yellowing symptoms developed in I. setosa indicator plants grafted with SPCSV infected sweet potato scions. qPCR test for the virus confirmed its presence in the I. setosa leaves. To the best of our knowledge, this is the first report on the occurrence of SPCSV in Hungary and the third in Europe (Valverde et al. 2004; EPPO 2021).

Physicochemical and sensory evaluation of sweet potato (Ipomoea batatas L.) restructured products produced in the Sinu Valley, Colombia

The purpose of the food industry is to ensure the availability of safe and nutritious food ingredients for human consumption. Sweet potato is a crop with excellent industrialization possibilities for human food due to its important nutrient content. The objective of this study was to evaluate the effect of an alginate-calcium sulfate-tripolyphosphate (PPTS) gelling system on the physicochemical and sensory characteristics of restructured sweet potato products. Fifteen formulations with varied concentrations of alginate, calcium sulfate, and PPTS were elaborated and subjected to a ordered-preference test. The physicochemical composition and color parameters of the preferred samples were determined, and the consumer acceptance, intention to purchase, and acceptability index (AI) were assessed. The preferred formulations (p ≤ 0.05) were F1, F6, F10, F11, and F14, and the gel formation was efficient at retaining water and preventing the restructured products from absorbing fat during frying. The restructured products with the highest water retention and lowest fat absorption were F11 (46.75%), F10 (44.53%), and F14 (43.29%). In the acceptance test, no differences (p ≥ 0.05) were found in the attributes softness, crunchiness, and sweet potato flavor. Formulations F6 and F14 obtained the highest acceptability index (AI), equal to or higher than 70%, indicating that they could represent viable alternatives for the industrial transformation of sweet potato for its possible commercialization.

Effect of tebuconazole and trifloxystrobin on Ceratocystis fimbriata to control black rot of sweet potato: processes of reactive oxygen species generation and antioxidant defense responses

Black rot, caused by Ceratocystis fimbriata, is one of the most destructive disease of sweet potato worldwide, resulting in significant yield losses. However, a proper management system can increase resistance to this disease. Therefore, this study investigated the potential of using tebuconazole (TEB) and trifloxystrobin (TRI) to improve the antioxidant defense systems in sweet potato as well as the inhibitory effects on the growth of and antioxidant activity in C. fimbriata. Four days after inoculating cut surfaces of sweet potato disks with C. fimbriata, disease development was reduced by different concentrations of TEB + TRI. Infection by C. fimbriata increased the levels of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and electrolyte leakage (EL), and the activity of lipoxygenase (LOX) by 138, 152, 73, and 282%, respectively, in sweet potato disks, relative to control. In the sweet potato disks, C. fimbriata reduced the antioxidant enzyme activities as well as the contents of ascorbate (AsA) and reduced glutathione (GSH) by 82 and 91%, respectively, compared with control. However, TEB + TRI reduced the oxidative damage in the C. fimbriata-inoculated sweet potato disks by enhancing the antioxidant defense systems. On the other hand, applying TEB + TRI increased the levels of H₂O₂, MDA, and EL, and increased the activity of LOX in C. fimbriata, in which the contents of AsA and GSH decreased, and therefore, inhibited the growth of C. fimbriata. These results suggest that TEB + TRI can significantly control black rot disease in sweet potato by inhibiting the growth of C. fimbriata.

Production of nisin and lactic acid from the starch of sweet potato by simultaneous saccharification and fermentation with two stage pH adjustment

Nisin is an antimicrobial peptide which is widely used as preservative, while lactic acid is a natural organic acid applied in the food industry. The aim of this work was to study the process for nisin and lactic acid production from starch of sweet potato with simultaneous saccharification and fermentation (SSF) by Lactococcus lactis subsp. Lactis with two stage pH adjustment. The factors impacting the nisin and lactic acid production including starch concentration, glucosidase concentration, CaCO₃ and Tween-80 were studied. The nisin titre reached a high of 2516.41 IU/mL, while the lactic acid reached a high of 37.06 g/L when the optimal conditions were 40 g/L starch, 100 U glucosidase/g starch, 2.5% CaCO₃ and 1 mL/L Tween-80. The lactic acid and nisin were separated by a two stage pH adjustment at last. The SSF of starch from sweet potato coupled with a two stage pH adjustment is a promising method to produce nisin and lactic acid.

Impact of sociodemographic factors on the consumption of tubers in Brazil

Background

Although tubers play a significant role in Brazilian agriculture, very little is known about the intake of tubers among the Brazilian population. The objective of this study was to characterize the intake of tubers across Brazil. The types of tubers consumed were quantified, and the impact of geographic and sociodemographic factors was assessed.

Methods

This cross-sectional study is based on dietary intake data of 33,504 subjects obtained from the Brazilian National Dietary Survey. All tuber containing foods were identified, and the contribution of different tubers to overall tuber consumption in Brazil was quantified. Descriptive analyses assessed the impact of macroregion and sociodemographic characteristics on tuber consumption, and differences in intake were assessed using statistical tests. Lastly, the dietary intakes of tuber consumers and non-consumers were compared after adjusting for energy and covariates to determine if there were any major differences in dietary intakes between the two groups.

Results

Fifty-five percent of the Brazilian population consumed tubers, which differed by macroregion. The intake of tubers among consumers also differed between macroregions. Overall, rural areas reported significantly higher mean daily intakes of tubers (122 g/day) among tuber consumers than urban areas (95 g/day). Mandioca and potato were the most commonly consumed tubers (59 and 43% prevalence, respectively, on any of the 2 days), while the highest daily intakes amongst tuber consumers across Brazil were noted for sweet potato (156 g/day) and potato (95 g/day). On a macroregion level, among tuber consumers, mandioca had the highest prevalence of consumption in the North (94%), Northeast (83%), and Central-West (68%), while consumption of potatoes was most prevalent in the Southeast (63%) and South (62%). Compared to women, small but significantly higher tuber intakes were noted for males (108 vs. 85 g/day). There were no significant differences in intakes among income quintiles. After adjusting for energy and other covariates, nutrient intakes between tuber and non-tuber consumers were not meaningfully different, with the exception of sodium (+ 6.0% comparing non-tuber to tuber consumers), iron (+ 6.1%), zinc (+ 5.7%), vitamin C (+ 8.3%), riboflavin (+ 9.0%), and folate (+ 7.9%).

Conclusions

Tuber consumption is influenced by regional and sociodemographic characteristics of the Brazilian population. When looking at energy-adjusted nutrient intakes, diets of tuber consumers have resulted in somewhat lower intakes of some micronutrients, namely riboflavin, folate, vitamin C, iron, sodium, and zinc.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-021-00709-1.

Influence of the source of starch and plasticizers on the environmental burden of starch-Brazil nut fiber biocomposite production: A life cycle assessment approach

Amidst the global plastic pollution crisis, bio-based polymers have been proposed as a potential substitute to tackle this issue. Owed to their biodegradability, biopolymers are generally regarded as eco-friendly during the post-consumer (disposal) stage. However, the environmental burden of the many production processes biopolymers and their components undergo better reflect the sustainable nature of these materials. Previous studies evaluating the Life Cycle Assessment (LCA) of starch-based composites have focused on commercially available starches, although other non-conventional starches can also be used to produce biopolymers. To address this knowledge gap, in the present study we evaluated the LCA of starch-Brazil nut fiber biocomposites prepared with starch from three different sources, Andean potato, corn, and sweet potato, and applying two different plasticizers, glycerol and sorbitol. Results indicated that the starch-based biocomposites were less impacting than conventional PLA-Brazil nut fiber and PP-glass fiber composites. The type of starch and plasticizer significantly influenced the environmental load of the production of the composites. The main drivers of these differences were the multiple agricultural practices, such as irrigation and fertilization, and the crop efficiency for starch extraction. Sorbitol was found to be many times more impacting than glycerol in most categories, which is due to the complex processing of sorbitol and high content in biocomposites with similar mechanical properties than glycerol. Additionally, Brazil nut fibers are presented as an eco-friendly and low-burden natural filler due to their easy processing and agricultural waste origin. The limitations, applications, and significance of the results were discussed.

Preparation and properties of phosphate starches from tuberous roots

The diversification of raw materials in the starch industries is a current strategy. However, the production of native starches does not meet market demand, and it is essential to expand the knowledge about chemical modifications in the same production line for different sources of starch. Phosphate starches are one of the most abundantly produced and widely used chemically modified starches. However, the effects of this modification may vary with the starch source and the reaction conditions. In this study, arrowroot, cassava and sweet potato starches were modified with sodium trimetaphosphate (STMP)/sodium tripolyphosphate (STPP) mixture under same conditions. The reaction time ranged from 7.5 to 120 min. Unmodified and modified starches were analyzed for phosphorus, amylose, morphology, X-ray diffraction pattern, crystallinity, swelling power, solubility, pasting and thermal properties. Phosphorus content linked to the starches increased with the reaction time, which affected the physicochemical properties of the three starches. The changes were more significant in all reaction times for cassava starch, followed by arrowroot. Due to its intrinsic characteristics, longer reaction times were necessary for more significant changes in sweet potato starch. Regardless of the starch source, as the reaction time increased, the average starch granule diameter, swelling power, solubility and peak viscosity increased. There was a decrease in setback in the longer reaction times for cassava and arrowroot starches. The changes in the reaction times allowed obtaining phosphate tuberous starches with different properties which can meet the demands of the food and non-food industries.

Contribution of ultrasound and slightly acid electrolytic water combination on inactivating Rhizopus stolonifer in sweet potato

Effects of ultrasound (US, 300, 400, and 500 W) and slightly acidic electrolyzed water (SAEW, 10, 30, and 50 mg/L) combination on inactivating Rhizopus stolonifer in sweet potato tuberous roots (TRs) were investigated. US at 300, 400, and 500 W simultaneous SAEW with available chlorine concentration of 50 mg/L at 40 and 55 °C for 10 min significantly inhibited colony diameters (from 90.00 to 6.00-71.62 mm) and spores germination (p < 0.05). US + SAEW treatment could destroy cell membrane integrity and lead to the leakage of nucleic acids and proteins (p < 0.05). Scanning and transmission electron microscopy results showed that US + SAEW treatment could damage ultrastructure of R. stolonifer, resulted in severe cell-wall pitting, completely disrupted into debris, apparent separation of plasma wall, massive vacuoles space, and indistinct intracellular organelles. US500 + SAEW50 treatment at 40 and 55 °C increased cell membrane permeability, and decreased mitochondrial membrane potential of R. stolonifer. In addition, US500 + SAEW50 at 40 °C and US300 + SAEW50 at 55 °C controlled R. stolonifer growth in sweet potato TRs during 20 days of storage, suggesting effective inhibition on the infection of R. stolonifer. Therefore, US + SAEW treatment could be a new efficient alternative method for storing and preserving sweet potato TRs.