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Sweet potato (Ipomoea batatas) is an important food crop that plays a pivotal role in preserving worldwide food security. Due to its polyploid genome, high heterogeneity, and phenotypic plasticity, sweet potato genetic characterization and breeding is challenging. Genome-wide association studies (GWASs) can provide important resources for breeders to improve breeding efficiency and effectiveness. GWASpoly was used to identify 28 single nucleotide polymorphisms (SNPs), comprising 21 unique genetic loci, associated with sweet potato storage root traits including dry matter (4 loci), subjective flesh color (5 loci), flesh hue angle (3 loci), and subjective skin color and skin hue angle (9 loci), in 384 accessions from the USDA sweet potato germplasm collection. The I. batatas 'Beauregard' and I. trifida reference genomes were utilized to identify candidate genes located within 100 kb from the SNPs that may affect the storage traits of dry matter, flesh color, and skin color. These candidate genes include transcription factors (especially Myb, bHLH, and WRKY family members), metabolite transporters, and metabolic enzymes and associated proteins involved in starch, carotenoid, and anthocyanin synthesis. A greater understanding of the genetic loci underlying sweet potato storage root traits will enable marker-assisted breeding of new varieties with desired traits. This study not only reinforces previous research findings on genes associated with dry matter and β-carotene content but also introduces novel genetic loci linked to these traits as well as other root characteristics. [ABSTRACT FROM AUTHOR]

(1) The development of sweet potato storage roots is impacted by nitrogen (N) levels, with excessive nitrogen often impeding development. Starch synthesis enzymes such as sucrose synthase (SUS) and ADP-glucose pyrophosphorylase (AGPase) are pivotal in this context. Although the effects of excessive nitrogen on the formation of sweet potato storage roots are well documented, the specific responses of IbSUSs and IbAGPases have not been extensively reported on. (2) Pot experiments were conducted using the sweet potato cultivar "Pushu 32" at moderate (MN, 120 kg N ha−1) and excessive nitrogen levels (EN, 240 kg N ha−1). (3) Nine IbSUS and nine IbAGPase genes were categorized into three and two distinct subgroups based on phylogenetic analysis. Excessive nitrogen significantly (p < 0.05) suppressed the expression of IbAGPL1, IbAGPL2, IbAGPL4, IbAGPL5, IbAGPL6, IbAGPS1, and IbAGPS2 in fibrous roots and IbSUS2, IbSUS6, IbSUS7, IbSUS8, IbSUS9, IbAGPL2, and IbAGPL4 in storage roots, and then significantly (p < 0.05) decreased the SUS and AGPase activities and starch content of fibrous root and storage root, ultimately reducing the storage root formation of sweet potato. Excessive nitrogen extremely significantly (p < 0.01) enhanced the expression of IbAGPL3, which was strongly negatively correlated with the number and weight of storage roots per plant. (4) IbAGPL3 may be a key gene in the response to excessive nitrogen stress and modifying starch synthesis in sweet potato. [ABSTRACT FROM AUTHOR]

Sweet potato (Ipomoea batatas) is an economically important food crop that is grown primarily for its edible storage roots. Several researchers have consequently been conducting studies to increase sweet potato yield, and an important aspect of this research involves understanding how storage root initiation occurs. Although significant progress has been made, several challenges associated with studying this crop have resulted in lagging progress compared to other crops and thus sweet potato storage root initiation is not clearly understood. This article highlights the most important aspects of the hormone signalling processes during storage root initiation that needs to be investigated further and suggests candidate genes that should be prioritized for further study, based on their importance in storage organ formation in other crops. Lastly, ways of overcoming the challenges associated with studying this crop are suggested. [ABSTRACT FROM AUTHOR]

An appropriate planting density could realize the maximum yield potential of crops, but the mechanism of sweet potato storage root formation in response to planting density is still rarely investigated. Four planting densities, namely D15, D20, D25, and D30, were set for 2-year and two-site field experiments to investigate the carbohydrate and lignin metabolism in potential storage roots and its relationship with the storage root number, yield, and commercial characteristics at the harvest period. The results showed that an appropriate planting density (D20 treatment) stimulated cambium cell differentiation, which increased carbohydrate accumulation and inhibited lignin biosynthesis in potential storage roots. At canopy closure, the D20 treatment produced more storage roots, particularly developing ones. It increased the yield by 10.18–19.73% compared with the control D25 treatment and improved the commercial features by decreasing the storage root length/diameter ratio and increasing the storage root weight uniformity. This study provides a theoretical basis for the high-value production of sweet potato. [ABSTRACT FROM AUTHOR]

Sweet potatoes are rich in cardioprotective phytochemicals with potential anti-platelet aggregation activity, although this benefit may vary among cultivars/genotypes. The phenolic profile [HPLC-ESI(−)-qTOF-MS2], cheminformatics (ADMET properties, affinity toward platelet proteins) and anti-PA activity of phenolic-rich hydroalcoholic extracts obtained from orange (OSP) and purple (PSP) sweet potato storage roots, was evaluated. The phenolic richness [Hydroxycinnamic acids> flavonoids> benzoic acids] was PSP > OSP. Their main chlorogenic acids could interact with platelet proteins (integrins/adhesins, kinases/metalloenzymes) but their bioavailability could be poor. Just OSP exhibited a dose-dependent anti-platelet aggregation activity [inductor (IC 50, mg.ml−1): thrombin receptor activator peptide-6 (0.55) > Adenosine-5′-diphosphate (1.02) > collagen (1.56)] and reduced P-selectin expression (0.75–1.0 mg.ml−1) but not glycoprotein IIb/IIIa secretion. The explored anti-PA activity of OSP/PSP seems to be inversely related to their phenolic richness. The poor first-pass bioavailability of its chlorogenic acids (documented in silico) may represent a further obstacle for their anti-PA in vivo. [Display omitted] • Purple (PSP) > orange (OSP) sweet potato is richer in phenolic compounds. • Chlorogenic acids (CGAs) are major sweet potato phytochemicals. • OSP but not PSP exhibit anti-platelet aggregation (PA) activity. • Sweet potatoes´ CGAs may be poorly absorbed in the gastrointestinal tract. • Sweet potatoes' CGAs may target human platelet-related proteins. [ABSTRACT FROM AUTHOR]

Starch and sugar properties and sweetness of storage root (SR) are vital to the economic value of sweet potato. To clarify the factors determining these properties of raw sweet potato, eleven varieties with different SR properties were selected to investigate the changes of starch and sugar-related traits, brix and amylase activities during the growth and development of SRs, and the correlation among these SR properties and the amylase activities were analyzed. Five β-amylase genes expressed in SRs were cloned, and their expression and characteristics were analyzed to reveal the involvement of amylase in these SR properties. The results showed total sugar, soluble sugar, reducing sugar content and brix varied greatly among different varieties and development periods, β-amylase activities were much higher than that of α-amylase in SRs, dynamically changed during the development of SRs, and decreased at the late stage of SR expansion. The expression of three β-amylase encoding genes were positively correlated with the total sugar content, and might play vital roles in starch and sugar metabolism in SRs. The brix of raw SRs was significantly correlated with total starch, amylose, amylopectin, total sugar content and reducing sugar content, but had no significant relationship with soluble sugar content and β-amylase activity. These results indicated that the brix of SR was determined by both starch and sugar components, and multiple β-amylases function together in starch and sugar metabolism in developing SRs. These findings provide important information for the improvement of sweetness and the quality of processed products in sweet potato. • 80-95DAP and 110-125DAP are the key periods for starch accumulation and degradation, resp. • β-amylase activities change dynamically and decrease at the late stage of SR expansion. • The brix had no significant relationship with soluble sugar content and β-amylase activity. • Multiple β-amylases function together in starch and sugar metabolism in developing SRs. • IbBAM 48829 , IbBAM 63470 , and IbBAM 87301 were positively correlated with the total sugar content. [ABSTRACT FROM AUTHOR]

Sweet potato (Ipomoea batatas), an important root crop, has storage roots rich in starch that are edible and serve as a raw material in bioenergy production. Increasing the storage-root starch contents is a key sweet potato breeding goal. Phosphoglucomutase (PGM) is the catalytic enzyme for the interconversion of glucose-6-phosphate and glucose-1-phosphate, precursors in the plant starch synthetic pathway. Plant PGMs have plastidial and cytosolic isoforms, based on their subcellular localization. Here, IbpPGM, containing 22 exons and 21 introns, was cloned from the sweet potato line Xu 781. This gene was highly expressed in the storage roots and leaves, and its expression was induced by exogenous sucrose treatments. The mature IbpPGM protein was successfully expressed in Escherichia coli when a 73-aa chloroplastic transit peptide detected in the N-terminus was excised. The subcellular localization confirmed that IbpPGM was localized to the chloroplasts. The low-starch sweet potato cultivar Lizixiang IbpPGM-overexpression lines showed significantly increased starch, glucose, and fructose levels but a decreased sucrose level. Additionally, the expression levels of the starch synthetic pathway genes in the storage roots were up-regulated to different extents. Thus, IbpPGM significantly increased the starch content of the sweet potato storage roots, which makes it a candidate gene for the genetic engineering of the sweet potato. [ABSTRACT FROM AUTHOR]

Carotenoids are important compounds of quality and coloration within sweet potato storage roots, but the mechanisms that govern the accumulation of these carotenoids remain poorly understood. In this study, metabolomic and transcriptomic analyses of carotenoids were performed using young storage roots (S2) and old storage roots (S4) from white-fleshed (variety S19) and yellow-fleshed (variety BS) sweet potato types. S19 storage roots exhibited significantly lower total carotenoid levels relative to BS storage roots, and different numbers of carotenoid types were detected in the BS-S2, BS-S4, S19-S2, and S19-S4 samples. β-cryptoxanthin was identified as a potential key driver of differences in root coloration between the S19 and BS types. Combined transcriptomic and metabolomic analyses revealed significant co-annotation of the carotenoid and abscisic acid (ABA) metabolic pathways, PSY (phytoene synthase), CHYB (β-carotene 3-hydroxylase), ZEP (zeaxanthin epoxidase), NCED3 (9-cis-epoxycarotenoid dioxygenase 3), ABA2 (xanthoxin dehydrogenase), and CYP707A (abscisic acid 8'-hydroxylase) genes were found to be closely associated with carotenoid and ABA content in these sweet potato storage roots. The expression patterns of the transcription factors OFP and FAR1 were associated with the ABA content in these two sweet potato types. Together, these results provide a valuable foundation for understanding the mechanisms governing carotenoid biosynthesis in storage roots, and offer a theoretical basis for sweet potato breeding and management. [ABSTRACT FROM AUTHOR]

Potassium (K) fertilization is a crucial component of sweet potato (Ipomoea batatas L.) production. The basis for K fertilizer recommendations in sweet potato production varies greatly and relies on studies conducted in the late 1950s–1970s. Changes in agronomic practices and increasing costs emphasize the need to revisit fertilizer recommendations. A field experiment was conducted to investigate the impact of seven different K fertilizer (K2O) application rates on sweet potato storage root yield, tissue K concentration, and economic implications in Mississippi. Incremental applications of K fertilizer did not influence sweet potato yield at any grade. Leaf tissue K concentration exhibited a quadratic trend in response to K fertilizer rate, with maximum leaf and root K content achieved at 269 and 404 kg·ha−1 K2O, respectively. Both the predicted K application rate for maximum yield and maximum profitability were the same, at 174 kg·ha−1 K2O. Accordingly, comparable sweet potato yields were achieved while applying substantially less fertilizer than the recommended rate. Further research is warranted to examine the impacts of only potassium fertilizer applications on soil characteristics and temporal trends in sweet potato potassium uptake, as well as refine fertilization recommendations for sweet potato production. [ABSTRACT FROM AUTHOR]

Essential nutrient concentrations in edible portions of crops can affect human health. Hence, field experiments were carried out for two growing seasons (2019 and 2020) at two degraded sites using a randomized complete block design in a factorial layout with three replications to evaluate the effects of biochar (B), poultry manure (PM), and their combined application on leaf nutrient concentrations and mineral composition of sweet potato. Each year, the experiment consisted of 4 × 3 factorial combinations of biochar (0, 10.0, 20.0, and 30.0 t ha−1) and poultry manure (0, 5.0 and 10.0 t ha−1). The results showed that the sole application of B and PM and their combined application, improved sweet potato leaf nutrient concentrations and mineral composition of sweet potato storage roots. In both years, there were significant interactions of B and PM (B × PM) on leaf nutrient concentrations and mineral composition of sweet potato that were determined, indicating the potential of B in enhancing PM use efficiency and improving better use of the nutrients in the PM. It was found that the highest dosage of combination of 30.0 t ha−1 B and 10.0 t ha−1 PM (B30+ PM10) gave the highest leaf nutrient concentrations and mineral composition of sweet potato at both sites. Lowest leaf nutrient concentrations and mineral composition was obtained for the control. The study indicated that B in combination with PM have the potential to improve sweet potato leaf nutrient concentrations and mineral composition of sweet potato storage roots for human health in severely degraded soils. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Effects of ultrasound (US, 300, 400 and 500 W) combined with slightly acid electrolytic water (SAEW) at 25, 40 and 55 °C on physiological, nutritional, sensory and microstructural characteristics of sweet potato tuberous roots (TRs, Pushu 32) during 10, 30 and 60 d of storage were investigated, to explore a potential postharvest preservation technique for TRs. Sweet potato TRs by US500+SAEW50 exhibited the strongest PAL activity (10.63 U g−1) at 30 d of storage and SOD activity (83,707.42 U g−1) at 60 d of storage, suggesting the activation of strong defense system. Sweet potato TRs by US500+SAEW50 also showed integral cell walls, and presented the highest sensory acceptability (73.45). In addition, rotting rate of the TRs treated by US500+SAEW50 was reduced by 55% after 6 months of storage as compared to the untreated TRs in industrial application. Therefore, US500+SAEW50 could be a promising postharvest preservation technique for sweet potato TRs. • Ultrasound (US) and slightly acidic electrolyzed water (SAEW) were combined. • US and SAEW could maintain firmness and reduce sprouting rate of sweet potato TRs. • US500+SAEW50 activated antioxidant defense system and protected cell wall integrity of TRs. • US500+SAEW50 kept sensory quality and increased commodity value of TRs. • US500+SAEW50 reduced rotting rate of sweet potato TRs after 6 months of storage. [ABSTRACT FROM AUTHOR]

Sweet potato is an important starchy crop, which is mainly utilized as food, animal feed, and fermented to produce fuel-grade alcohol. However, the genetic mechanism regulating starch content in sweet potato is not yet fully understood. In this study, transcriptome analysis was performed in sweet potato cultivars Luoxushu 8 (high starch), Zhengshu 20 (low starch), and 12 hybrid F1 lines (six high-starch lines and six low-starch lines), which detected a total of 85,493 genes. The high and low-starch content groups were compared and found that 47 and 64 genes were up-regulated and down-regulated, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that seven differentially expressed genes were significantly enriched in the ATP-binding cassette (ABC) transporter pathway. Among them, five genes (annotated as ABCB1) that might involve in the auxin transport were significantly down-regulated in high-starch group. Meanwhile, the storage root sizes of Zhengshu 20 were higher as compared with Luoxushu 8. Simultaneously, four of the five differentially expressed genes enriched in the starch and sucrose metabolism pathway were up-regulated in high-starch group. These results provided the basis for the study of starch content in sweet potato storage root. [ABSTRACT FROM AUTHOR]

Postharvest sprouting is a major problem for the storage of sweet potato. This study compared the effect of D-fenchone with methyl naphthacetate (MENA) treatments on the sprouting of 'Yan 25′ sweet potato. The untreated control roots sprouted within 4 days however the roots fumigated with 200 μL / 23 L D-fenchone or MENA completely inhibited the sprouting of freshly harvested 'Yan 25′ during 14 days storage at 30 ℃. Furthermore, treating established sprouts (0.5 cm) with MENA or D-fenchone resulted in damaged sprouts after seven days following treatment with higher MDA content and these sprouts eventually died. Transcriptomic analyses revealed that both D-fenchone and MENA inhibited cell wall synthesis and disrupted auxin and cytokinin pathways in the storage roots, by which suppressed the sprouting. The RNA-seq results of established sprouts showed that both D-fenchone and MENA promoted ethylene and reactive oxidative species (ROS) pathways, which were correlated with the physical damage. In addition, D-fenchone and MENA inhibited auxin pathway, MENA changed cytokinin and D-fenchone disrupted polyamine, cell division and cellulose biosynthesis pathways which all may have contributed to sprout suppression. • D-fenchone works better than MENA in inhibiting sweet potato sprouting. • The inhibiting effect of D-fenchone on sprouting of sweet potato is reversible. • D-fenchone/MENA induced membrane damage and senescence in established shoots. • Plant hormones were associated with D-fenchone/MENA induced sprout suppression. • Transcriptional responses of established shoots to D-fenchone is quicker than MENA. [ABSTRACT FROM AUTHOR]

This work was conducted during two successive seasons (2018 and 2019) at the experimental research station, Shandweel, Sohag, Egypt to study the effectiveness addition methods of the fungus, Beauvariabassiana on growth, yield quality and some of the chemical constituents, moreover, associated insects and their damages to vegetative and storage roots growth were calculated of sweet potato plants growing under Sohag governorate conditions. The obtained results indicated that the different addition treatments of B. bassiana wereshowed an increase in growth traits when the plants were sprying twice by B. bassiana given the highest values of plant length, fresh weight compared with other treatments studied in both seasons. The gained results of yield and its contents included that addition of B.bassianain soil twice gave the best values of total yield, marketable yield, theaverage weight of storage roots as well as highest dry matter percentage of storage roots compared with other treatments, at the same time the control treatment showed the lowest of values of all studied traits in both seasons. Soil application of B. bassiana twice was affected significantly on chemical constituents of sweet potato storage roots (nitrogen%, phosphorus%, potassium%, Protein% and starch%) except potassium% and starch in the first season. Twice foliar application of fungus was the most effective application on leave defoliators and recorded the lowest number of whiteflies. [ABSTRACT FROM AUTHOR]

Hot air treatment is currently the main pretreatment method to promote postharvest callus healing of sweet potatoes. To improve the existing problem, such as high energy consumption, low efficiency, instability, in sweet potato callus formation technology. The purpose of this study was to find the optimal conditions of High Temperature Short Time (HTST) hot air treatment which could promote postharvest sweet potato callus formation. The lignin content, soluble solid content, weight loss rate, and decay rate of sweet potato were selected as the key indices in this study. The indices of sweet potatoes were measured after 15 d of (25±5) ℃ storage. Single-factor and response surface methods were used to optimize the callus formation conditions of sweet potato within hot air treatment. In the single-factor experiment, the temperature and time of treatment were used as variables. The HTST hot air treatment temperature range was set as 40, 45, 50, 55, 60 and 65 ℃, and the treatment time range was set as 30, 60, 90, 120, 150, and 180 min. By Design-Expert 8.0 software, a central combination of two factors and three levels was used to design the central composite design for sweet potato hot air treatment. The quadratic multivariate regression equations of lignin, soluble solids, weight loss rate, and decay rate were obtained. The results of variance analysis of lignin content, soluble solid content, weight loss rate, and decay rate of sweet potato after hot air treatment showed that the four equations of hot air treatment had high significance, good fitting degree, and small test error. Hence, this model could be used to predict the data of sweet potato after callus formation. The results of the single-factor experiment showed that the soluble solids and starch content of sweet potato after callus formation could be maximized maintained when the treatment time reached 150 min. And the decay rate and weight loss rate after storage could be maximized reduced. At the same time, When the hot air treatment temperature reached 50 ℃, the soluble solid content and starch content of sweet potato after shelf-life storage was significantly higher than that of other treatment temperatures. Meanwhile, the weight loss rate and the decay rate were the lowest in all treatment groups. Within the single-factor experimental results, the two-factor and three-level center combination design of the treatment temperature and treatment time was performed for quadratic multiple regression fitting. The quadratic multinomial regression equations of lignin content, soluble solid content, decay rate, and weight loss rate were obtained. At the same time, the model was tested and the four equations were found to have high significance and a good degree of the fitting. The model was used to predict the four parameters of sweet potato callus formation and analyze the response surface. The results showed that the callus formation effect of sweet potato in shelf-life storage was more influenced by hot air treatment temperature than treatment time. On the other hand, the optimal conditions for promoting the callus formation of sweet potato were 49 ℃ and 137 min, which could effectively promote the lignin synthesis, weight loss rate, and decay rate of sweet potato callus. Compared with the control, the content of starch was higher by 76.30%, soluble solid content was higher by 32.08% and ascorbic acid content was higher by 81.19% in sweet potato after shelf storage, which was all significantly increased by hot air treatment. Moreover, the weight loss rate and decay rate of sweet potato after storage were reduced by 22.14% and 79.95%, respectively. All the five indices provided the 49 ℃ and 137 min was an optimized post-partum callus process for sweet potato production. [ABSTRACT FROM AUTHOR]

Background: Sweet potato (Ipomoea batatas (L.) Lam.) is a highly heterozygous autohexaploid crop with high yield and high anthocyanin content. Purple sweet potato is the main source of anthocyanins, and the mechanism of anthocyanin biosynthesis in storage roots has not been fully revealed. Results: In order to reveal the mechanism of anthocyanin biosynthesis and identify new homologous genes involved in anthocyanin biosynthesis in the storage roots of sweet potato, we used Ningzishu 1 and Jizishu 2 as parents to construct a F1 hybrid population. Seven anthocyanin-containing lines and three anthocyanin-free lines were selected for full-length and second-generation transcriptome analyses. A total of 598,375 circular consensus sequencing reads were identified from full-length transcriptome sequencing. After analysis and correction of second-generation transcriptome data, 41,356 transcripts and 18,176 unigenes were obtained. Through a comparative analysis between anthocyanin-containing and anthocyanin-free groups 2329 unigenes were found to be significantly differentially expressed, of which 1235 were significantly up-regulated and 1094 were significantly down-regulated. GO enrichment analysis showed that the differentially expressed unigenes were significantly enriched in molecular function and biological process. KEGG enrichment analysis showed that the up-regulated unigenes were significantly enriched in the flavonoid biosynthesis and phenylpropanoid biosynthesis pathways, and the down-regulated unigenes were significantly enriched in the plant hormone signal transduction pathway. Weighted gene co-expression network analysis of differentially expressed unigenes revealed that anthocyanin biosynthesis genes were co-expressed with transcription factors such as MYB, bHLH and WRKY at the transcription level. Conclusions: Our study will shed light on the regulatory mechanism of anthocyanin biosynthesis in sweet potato storage roots at the transcriptome level. [ABSTRACT FROM AUTHOR]

The sweet potato is less known in Romania. The highly different storage conditions between sweet potatoes (lpomoea batatas, Convolvulaceae family) and potatoes (Solanum tuberosum, Solanaceae family) make it difficult to maintain the quality of the tubers during storage. Sweet potatoes are sensitive to relatively low temperatures (<12°C), which can produce chilling injuries. The wounds created by the cold can lead to over-infection with storage pathogenic fungi. In order to reduce the potential losses caused by storage fungal infections, we recommend the use of beneficial yeasts, with biocontrol activity. These yeasts were selected from the natural epiphytic microbiota and do not present toxicity risks to consumers. The selected isolates have shown inhibitory activity against the main storage pathogenic fungi of sweet potato: Botrytis cinerea, Fusarium oxysporum, Penicillium sp, Rhizopus stolonifer and Sclerotium bataticola. [ABSTRACT FROM AUTHOR]

Root and tuber crops (RTCs) produce a variety of edible belowground organs constituting the second most important source of carbohydrates to humans and the most important in sub-Saharan Africa. This review focuses on the development of adventitious roots (ARs), differentiation of storage roots and the growth and decay of non-storage roots. The root system of RTCs comprises ARs but the storage organs differ; confusingly, much of the literature refers to them all as tubers. Swelling of ARs to form storage roots (SRs) in cassava and sweet potato results from expansion of root cambium and proliferation of starch storage tissue with starch biosynthesis genes highly expressed, and lignin biosynthesis genes down regulated. Several genes play a role in SR development in sweet potato including two MADS-box transcription factors and in cassava, potato and sweet potato storage organ initiation and development is related to KNOX1 activity. The small number of studies makes generalization difficult, but several show that maximum length coincides with the start of rapid growth of storage roots/tubers. Different patterns of growth may reflect differences in soil water and nutrient availability. Many ARs appear to be short-lived. Typically the rooting depth of potato was < 1m with a maximum root length of 7-12 km/m² while for cassava, rooting depth was deeper (> 1m), but root length was less (1-2.84 km/m²). We highlight the paucity of studies of RTCs, the inconsistent use of terms to describe roots and storage organs and the need to characterize the longevity and functionality of different root types especially SRs. [ABSTRACT FROM AUTHOR]

BACKGROUND: Sweet potato weevil, Cylas formicarius (Fabricius) attacks stems and storage roots of sweet potato, Ipomoea batatas, and is a major pest of this globally significant crop. To minimize the immigration of weevils into sweet potato fields from nearby donor habitat, we assessed scope for a barrier plant approach. Here, we report a novel, two‐stage, multiple choice olfactometer method to screen candidate barrier plant species and a field study of the effects of shortlisted barrier plants of weevil movement and plant damage. RESULTS: Initial work established that a combination of sweet potato foliage and storage root was significantly more attractive to adult C. formicarius than either tissue alone in the distal chamber of choice arms. Among 15 candidate barrier plant species in intermediate chambers in arms, spring onion, oregano, chilli, basil, sweetcorn, fennel, lime mint and lemongrass significantly reduced passage of C. formicarius. Of these, sweetcorn and lime mint significantly reduced the numbers of oviposition holes in sweet potato storage roots. A field study showed that basil and chives were effective barrier plants for reducing weevil damage to sweet potato storage roots. CONCLUSION: Our method has utility for screening additional candidate plants, and suggests that weevil dispersal and subsequent oviposition are affected by passage through some plants, suggesting scope for barrier plants to contribute to the management of this major pest. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

To unravel changes in the structures and digestibility of sweet potato starch in the roots during postharvest storage (0 to 20 days), starches are isolated and characterized in terms of amylose content, polyphenols amount, molecular molar mass (Mw), molecular reassociation and multi-scale reassociated structures after cooking. Results reveal that starch digestibility decreases with a concomitant increase on resistant starch (RS) fraction during the first 10 days. These changes are associated with an increase of ordered structures, amylose and polyphenols content as well as the starch fractions with molecular weight of (2.0–2.5) × 107 g/mol. However these trends get reversed at higher postharvesting periods. Correlation matrices reveal that the short-range ordered structures and starch molecular reassociation behavior of starch paste and polyphenol content are the key factors in determining the RS content. Besides, the short-range ordered structures, specific starch molecular weight distribution and amylose of starch paste can be tailored for modulating the digestibility by controlling the postharvest storage time. This study opens a promising pathway to tailor starch digestibility via simply controlling the postharvest storage time of starch-containing crops. • Starch structures, amylose and polyphenols change during the postharvest storage. • Postharvest storage influences the starch digestibility. • Polyphenols and starch ordered structure determine the content of resistant starch. • Postharvest storage tailors starch structures and digestibility. [ABSTRACT FROM AUTHOR]

Key message: We developed transgenic sweet potato with Spomin (sucrose-inducible minimal promoter)-GUS gene-fused constructs. Induced GUS activities by Spomin were higher than those by CaMV 35S promoter. We developed transgenic sweet potato (Ipomoea batatas L. Lam. cv. Kokei no. 14) plants with Spomin (sucrose-inducible minimal promoter)-GUS gene-fused constructs with signal peptides for sorting to cytosol, apoplast and ER, and we analyzed the GUS expression pattern of cut tissue after sucrose treatment. Induced GUS activities by Spomin were several hundred times higher than those by the CaMV 35S promoter. Also, GUS activities in storage roots induced with a Spomin–cytosol-GUS construct were higher than those with either Spomin–apoplast or –ER-GUS constructs. The induced GUS activities by Spomin were higher in storage roots without sucrose treatment than those with sucrose treatment. Chilling (4 °C) storage roots with Spomin constructs for 4 weeks produced higher GUS activities than in storage roots stored at 25 °C for 4 weeks. The calculated maximum GUS content in the storage roots was up to about 224.2 μg/g fresh weight. The chilling treatment increased the free sucrose content in the storage roots, and this increase in endogenous sugar levels induced increased GUS activities in the storage roots. Therefore, Spomin appears to be a useful promoter to develop protein production systems using sweet potato variety Kokei no. 14 storage roots by postharvest treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Strain P32-3 inhibited C. fimbriata mycelial growth and spore germination. • Strain P32-3 effectively controlled postharvest sweet potato black rot. • The down-regulated DEGs were related to C. fimbriata growth and pathogenicity. • Strain P32-3 may be a potential biocontrol agent against postharvest sweet potato black rot. Sweet potato black rot is a common postharvest disease caused by the pathogenic fungus Ceratocystis fimbriata. The toxins produced by infected tubers are potentially harmful to humans. Plant endophytic bacteria may serve as biocontrol agents for protecting crops (including vegetables) during postharvest storage without detrimental effects on humans or other animals. In this study, 11 bacterial strains of Bacillus , Priestia , Blautia , Pseudomonas , and Sphingomonas species were isolated from sweet potato storage roots, of which only one strain (P32-3), which was identified as Bacillus altitudinis , strongly inhibited C. fimbriata mycelial growth and spore germination. Furthermore, the volatile organic compounds and cell-free supernatant of strain P32-3 repressed C. fimbriata growth. Additionally, P32-3 treatments significantly decreased the disease spot diameter and depth on harvested sweet potato roots. A total of 981 differentially expressed genes were identified by comparing the transcriptomes of the control and P32-3-treated mycelia. Strain P32-3 significantly altered the expressions of genes related to cell wall integrity, the cell membrane, spore germination, energy metabolism, pathogenicity, and oxidative stress. In addition, RNA-seq results were validated by a quantitative real-time polymerase chain reaction analysis. Our results indicate that B. altitudinis strain P32-3 can inhibit C. fimbriata growth and development and protect postharvest sweet potato storage roots from C. fimbriata infection. The study findings provide the theoretical basis for future investigations on the utility of strain P32-3 for protecting sweet potato against black rot during the postharvest stage. [ABSTRACT FROM AUTHOR]

Ceratocystis fimbriata Ellis & Halsted is a ubiquitous and devastating phytopathogen causing significant losses in harvested sweet potatoes. Furanoterpenoid toxins elicited by the C. fimbriata can cause hepatotoxicity, pneumonia and lung edema, and seriously threaten human health. Therefore, controlling C. fimbriata and limiting the storage losses of sweet potatoes are of critical importance to the economic value of sweet potatoes and human health. In this review, the mechanisms of phytopathogen infection and dispersal are summarized. Furanoterpenoid toxins incidence in the tuberous root and their toxicology are reviewed. Furthermore, the control methods of C. fimbriata and postharvest sweet potato spoilage were emphasized. Equipped with these understandings, this review aims to provide an important theoretical basis for the efficient prevention and control of C. fimbriata and the maintaining of the storage quality of sweet potatoes. Additionally, the key problems in sweet potato postharvest storage and areas of research that warrant further studies are analyzed and identified. Per our knowledge, the current manuscript is the first review to provide integrated and up-to-date information for scientists working with C. fimbriata. [Display omitted] • Ceratocystis fimbriata is a widely distributed postharvest sweet potato spoilage fungus. • Wounding types, spore concentration, temperature, and humidity affected disease dispersal. • Current understanding of the furanterpenoids incidence in root tube and their toxicology was summarized. • Current control strategies consist of physical, chemical, and biological methods, including essential oils. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cinnamaldehyde (CA) exhibited antifungal effect on Fusarium solani. • CA disrupted mitochondrial function and induced ROS accumulation. • ROS peroxidized mitochondrial cardiolipin and initiated apoptosis in F. solani. • CA holds promise as a preservative for postharvest storage 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. [ABSTRACT FROM AUTHOR]

Sprouting is an important postharvest problem in the transport and storage of sweet potato. This study investigated the effect of carvone fumigation on the development of sprouts in 'Yan 25′ sweet potato storage roots and sprouts. The results showed that visible buds could be observed in untreated root after 4 d at 30 ℃, however no buds were found on carvone treated sweet potato, even after 14 d storage. The levels of β-amylase activity were lower in the carvone treated roots and were associated with higher starch content. Treatment of sweet potato sprouts with carvone severely damaged the sprouts after 24 h and finally turned black after 72 h treatment, resulting in higher MDA content. The transcriptomic analyses showed that the manipulation of auxin distribution, cytokinin metabolism, cell wall synthesis and cell wall loosening processes were associated with carvone inhibition of sprouting in sweet potato roots. Further transcriptomic analyses on sweet potato sprouts revealed a similar transcription profile except that the gibberellin metabolism was also affected in the sprouts by carvone treatment. The up-regulation of apoptosis related genes in carvone treated sprouts, included UDP- D -apiose/UDP- D -xylose synthase (UAXS), ACC oxidase (ACO), tonoplast intrinsic protein (TIP), respiratory burst oxidase (RBOH), senescence associated gene (SAG) which were correlated with the lethal effect of carvone on the sprout. Two conceptual models elucidating the molecular mechanism of carvone inhibited sprouting in sweet potato are proposed. The further elucidation of this mechanism will potentially lead to a theory to optimize the method in sprouting inhibition of sweet potato. • Carvone inhibited sprouting of sweet potato storage roots. • Carvone fumigation resulted in apoptosis and blacken of sweet potato sprouts. • Carvone retained starch contents and suppressed β-amylase activities. • Altered Aux, CTK and GA pathways were associated with carvone inhibited sprouting. • Changes in SAGs were correlated with carvone induced apoptosis in the sprouts. [ABSTRACT FROM AUTHOR]

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. Interaction between carotenoid and starch biosynthesis in sweet potato amyloplasts. [Display omitted] • Starch and carotenoids compete for the same metabolite precursors. • Reduction of starch is indirectly linked to carotenoids through pyruvate biosynthesis. • Presence of carotenoids changes the cellular ultra-structures of the plastid. • All membrane structures in the root plastid are derived from the plastid envelope. • Functions of membrane structures include synthesis, transport and storage of carotenoids. [ABSTRACT FROM AUTHOR]

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. • Overexpression of IbCYP82D47 increases carotenoid contents in transgenic sweet potato storage roots. • Overexpression of IbCYP82D47 influences the expression of genes involved in carotenoid biosynthesis. • IbCYP82D47 physically interacts with a carotenoid biosynthesis related protein IbGGPPS12. [ABSTRACT FROM AUTHOR]

Sweet potato (Ipomoea batatas) growth faces two critical problems: variability in storage root (SR) number and size among individual plants, and skinning injuries that render the SR susceptible to pathogen infections during storage. We hypothesized that application of potassium (K) fertilizer, an essential mineral for sweet potato, would contribute to increased yield, uniformity, and skin quality of SRs. Sweet potatoes were grown in sandy soil, which is poor in K, and in loess soil. The fertilizers potassium chloride (KCl) and polyhalite were applied before planting. Polyhalite is a hydrated sulfate of K, calcium, and magnesium that has been shown to improve potato skin appearance. Soil type was the major factor affecting SR yield—higher in sandy vs. loess soil. The K fertilizers did not affect yield in either soil type, or improve SR uniformity. However, the skin of the SRs from loess soil had more phellem layers and larger phellem cells following fertilization, mainly with KCl. Accordingly, the expression of suberin marker genes was significantly higher in mature vs. immature skin of SRs fertilized with KCl. Overall, soil type was the major factor affecting sweet potato yield, and addition of K positively affected skin morphology and related gene expression. [ABSTRACT FROM AUTHOR]

Cull sweet potato storage roots that would otherwise be left unharvested in production fields or dumped as waste from excess supplies in storage may be available for use as livestock feed at competitive pricing relative to other feedstuffs. Given this potential economical source of nutrients for consumption by beef cattle, the objective of this study was to assess cow-calf performance using unprocessed sweetpotato storage roots as a winter supplement to grazing cow-calf pairs as compared to whole cottonseed or no supplement. Fall-calving multiparous Bos taurus crossbred cows in Prairie, MS, were allotted ad libitum access to mixed-grass pasture with tall fescue as the predominant forage species and randomly allocated to one of three as-fed basis supplement groups: 6.8 kg/cow/d of sweetpotato storage roots (SWP); 2.3 kg/ cow/d of whole cottonseed (WCS); or no supplement (NONE). Supplements were offered to cows on a group basis on every Monday, Wednesday, and Friday for 93 d each winter initiating December 5, 2016 (n = 81) and December 11, 2017 (n = 105). Cow BCS on a scale of 1 to 9 (1 = emaciated; 9 = obese) at supplementation initiation was 6.1 ± 0.1. From supplementation initiation until calf weaning in March, change in cow BCS (P < 0.01) was greatest for NONE (-1.1 ± 0.1), intermediate for SWP (-0.7 ± 0.1), and least for WCS (-0.4 ± 0.1). Adjusted 205-d calf BW was 16.9 ± 3.8 kg heavier (P < 0.01) in steers than heifers but did not differ (P = 0.41) among supplementation groups. Although nursing calf performance was not impacted by supplementation regime, results suggest that cull sweetpotato storage roots may be an effective feedstuff for winter supplementation intended to reduce BCS loss in lactating beef cows. Additional research to determine optimal frequency and quantity of SWP supplementation is warranted [ABSTRACT FROM AUTHOR]

Excess consumption of sweet potato storage roots (SWP) poses an acidosis risk to cattle that may be mitigated by limit-feeding strategies. Yet limit-feeding is often administered to achieve mean desired daily DMI in groups of cattle with little regard for DMI variation among individuals. The study objective was to assess variation in daily DMI of SWP by beef heifers in limit-fed, competitive feeding groups. Twenty-four 9- to 10-mo-old Bos taurus crossbred heifers were stratified by initial BW (261.9 ± 8.8 kg) to 4 paddocks (6 heifers/ paddock) and offered SWP (24.9% DM on an as-fed basis; 7.7% CP, 5.9% ADF and 80% TDN on a DM basis) supplementation daily at a rate of 3.4 kg DM/ paddock with ad libitum access to mixed-grass pasture. After a 7-d acclimation period in which all heifers were trained to use a GrowSafe system, daily SWP DMI was monitored for 39 days. Standard deviation estimates were calculated from DMI data and used to classify DMI into the following levels: low (2.0 kg, >0.5 SD). Half of the heifers (mean SWP DMI = 0.0 ± 0.02 kg) never consumed SWP at the high DMI level, but 42% of the heifers (mean SWP DMI = 1.1 ± 0.02 kg) consumed SWP at the high DMI level for at least 18 days over the study duration. No heifers consumed at the moderate DMI level more than 16 days during the trial. This suggests that DMI of individual cattle offered SWP in limit-fed groups often either exceeds by approximately 2-fold per animal mean values of SWP offered per group or is at or near zero. Additional research is needed to elucidate optimal group feeding strategies to achieve individual DMI targets among cattle offered SWP. [ABSTRACT FROM AUTHOR]