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The 2030 Agenda for Sustainable Development Goals of the United Nations puts forward a transformational vision to cope with food security, nutrition, and health challenges, in which sweet potato can play an important role. Globally, sweet potato production is valued at $53.83 billion. The Agricultural Research Council of South Africa (ARC) sweet potato research and development (R&D) program over the past seven decades delivered 31 genetically improved cultivars via demand‐led breeding, managed the collection and maintenance of 375 accessions, contributed toward the optimization of cultivation practices, developed crop protection and diagnostic services, and provided streamlined seed systems and technology transfer in processing and enterprise development. The ARC's work is part of a large number of interdependent global programs committed to improving livelihoods and nutrition through sweet potato. This review shares and analyses major achievements, highlights unique research contributions achieved through partnerships, and discusses bottlenecks on funding and uptake of technologies. New research imperatives will involve root phenotyping, employing marker‐based technologies, and genome‐wide association studies through new funding received recently. Exploration of the commercialization potential of processed products made from orange‐fleshed sweet potato will be a major focus of the R&D program. Expansion of partnerships, marketing, and financing will be important for future contribution of sweet potato to the economy. Core Ideas: Sweet potato has great potential to address several Sustainable Development Goals of the United Nations.A comprehensive sweet potato research and development program described herein provided technology across the full value chain.Screening methods for wilt disease, nematodes, protein content, virus, and crop development are highlighted.Expansion of partnerships and financing is essential to retain research momentum.Modern technologies must be key in new research imperatives.This article provides important lessons for public breeding efforts. [ABSTRACT FROM AUTHOR]

The breeding stages of a clonally propagated crop entails several steps and can take more than five years from hybridisation till cultivar release. The Accelerated Breeding Scheme (ABS) in sweetpotato relies on the use of multiple locations at the early breeding stages to reduce the years required for field evaluation. The aim of the study was to select the best progenies based on the ABS in sweetpotato towards the development of genotypes that combine high protein content with other important agronomic traits. Botanical seeds were generated from crosses between two diverse sets of parents, crossed using a North Carolina II design. F1-progenies (n = 363) were planted in a lattice design at three distinct locations during the 2017/18 planting season. Parameters recorded included pest and disease infestation, storage root traits and yield components, root protein content and nutrient related traits. Nutrient content was determined by near-infrared spectrometry. Analysis of variance and multiple t-distribution test and best test grouping were performed. There were significant differences (p < 0.001) among the genotypes for total number of roots, total root yield, marketable number of roots and marketable yield. The severity of Alternaria blight was significantly higher at Jozini. Forty progenies were selected (12.8% selection pressure) based on agronomic performance. Using the nutrient content results, four promising orange-fleshed clones (NC12-9, NC53-11, NC55-8, NC55-2) and one cream-fleshed clone (NC51-1) were identified with high storage root protein, iron and zinc contents. NC51-1 and NC55-2 produce promising storage root yields. The ABS approach is resource-demanding in the first phase but advances progenies rapidly to the subsequent breeding phases for cultivar release. [ABSTRACT FROM AUTHOR]

• Cooking negatively affected the protocatechuic acid and vanillic acid content. • Cooking increased the antioxidant power (FRAP activity) in all six cultivars. • Solar drying (blanched) increased the β-carotene content in C5-1 and Bophelo. • Novel information provided on the changes in phytonutritional components. Sweet potatoes are key to food security, nutrition and income generation in sub-Saharan Africa, and orange-fleshed sweet potato contributes towards pro-vitamin A intake. This study investigated the changes in phytonutritional components and antioxidant activity in six sweet potato cultivars with varying flesh colour in fresh form and during different postharvest thermal treatments; conventional cooking (boiled), drying in hot-air convection oven dryer (14 h at 60°C) as well as blanched and unblanched indirect solar drying (at 20-60°C for 48 h). Overall thermal processing enhanced the retention of total protein content, Zn, total phenols, epicatechin, protocatechuic acid, and 2-caffeoyl-L-tartaric acid in all six cultivars compared to the fresh form. However, vanillic acid was not detected in most of the cultivars after cooking except in 'C5-1. Hot-air convection oven drying significantly increased the total phenolic content in all six cultivars compared to the fresh form and other drying methods, while hot-air oven dried 'Monate' contained the highest total phenols and protocatechuic acid. Similarly, hot-air oven dried 'C5-1' showed the highest epicatechin and vanillic acid content compared to the fresh form and other drying methods. Cooking increased the 2-caffeoyl-L-tartaric acid in all six cultivars, compared to the fresh form and the highest content was detected in cooked 'Bophelo'. Blanching and solar drying improved the β-carotene content in orange cultivars 'Beauregard', 'Bophelo' and 'C5-1', of which 'C5-1' showed the highest β-carotene content. Cooking increased the antioxidant power (FRAP activity) in all six cultivars and increased the protein content and Zn content in 'Ndou' and '199062.1' respectively. The study provided novel information on the changes in phytonutritional components of different sweet potato cultivars including the cream cultivars 'Monate' and 'Ndou' and orange cultivars 'Bophelo' and 'C5-1' bred locally in South Africa, using different processing methods. [ABSTRACT FROM AUTHOR]

Sweetpotato improvement is influenced by selection of superior and best combiner parents with desirable traits. This study determined the genetic control of root nutrients: protein, β-carotene, starch, simple sugars and selected minerals. Two heterotic groups of five parents were crossed using a North Carolina II mating design to generate 25 full-sib families. Family 'Bophelo × 2008-3-1' did not produce seeds, therefore, only 24 families were evaluated in the field using a 14 × 26 simple lattice design with three replications at two sites. Root yield-related traits were recorded at harvest and nutrient content determined using Near-Infrared Spectroscopy. Genetic control parameters (general and specific combining ability and mid-parent heterosis) were calculated for the two sites. Significant interactions (p < 0.05) between female, male and/or families with sites were found in most nutrient and yield components. The highest overall mean values for protein, β-carotene, iron, zinc, fructose and glucose were recorded at the Jozini site whereas calcium, magnesium, sucrose and starch were higher at the Roodeplaat site. Significant (p < 0.01) interactions between female or male general combining ability and specific combining ability of family effects with sites were also found for most nutrient quality traits. The female parents '199,062.1 × Ndou' and '2012-8-4' were the best general combiners for most of the nutrient traits at the two sites while male parents '2003-8-1' and 'Khumo' were the two best general combiners. Several families had the highest specific combining ability for different nutrients in the two sites. 'Bophelo × Khumo' had the highest specific combining ability for protein, β-carotene zinc and iron at Jozini while family 'Bophelo × 1987-2-1' had the highest protein, iron and zinc content. Family '2012-8-4 × 2008-3-1' had over 95% heterosis for root β-carotene content at Roodeplaat. Family 199,062.1 × Ndou × 2005-5-5 had 35% for MRY. Understanding the genetic control of root nutritional quality traits is key to design suitable breeding strategies to improve these nutrients which are vital in combating malnutrition particularly in sub-Saharan Africa. [ABSTRACT FROM AUTHOR]

The prevalence of Sweet potato virus 2 (SPV2) and Sweet potato chlorotic stunt virus (SPCSV) in the Limpopo, Mpumalanga, and Gauteng provinces of South Africa was determined using serological and nucleic acid based methods. Cloning and sequencing part of the coat protein (CP) gene and the complete genome using next generation sequencing (NGS) were also conducted to characterize and determine the sequence variability in SPV2 isolates. Primers designed in the current study successfully detected and confirmed the prevalence of SPV2 in the three provinces surveyed. The pairwise comparison of the amino acid (aa) sequences encoding the CP gene region confirmed that isolates in this study are related to SPV2, sharing a 94% to 99% CP aa identity with those originally reported in South Africa. The East African (EA) strain of SPCSV was also detected in the three provinces surveyed. Phylogenetic analysis using part of the CP encoding nucleotide (nt) sequences showed that the South African isolates correspond to but are distinct from the other EA strains of SPCSV used as reference sequences. Assessment of varieties and breeding lines' response to multiple infection of potyviruses identified variety NC1560, breeding lines 2002‐21‐1 and 2006‐5‐4 as promising for inclusion in future breeding programs as sources of parent material for virus tolerance. Core Ideas: Sweet potato virus 2 and Sweet potato chlorotic stunt virus were confirmed to infect sweet potato in South Africa.The South African isolates of sweet potato chlorotic stunt virus were confirmed to belong to the East African serotype of the virus.Screening of varieties and breeding lines aid selection of potential tolerance varieties for inclusion in breeding programs. [ABSTRACT FROM AUTHOR]

• Root protein estimation of 53 introduced and 174 local sweetpotato accessions. • NIRS is a convenient and effective method for high-throughput assessment of protein content. • The large genetic variability opens up possibilities for breeding for higher root protein levels in sweetpotato. • The study provides much needed information on protein content of diverse sweetpotato germplasm. Sweetpotato [ Ipomoea batatas (L.) Lam.] is a relatively cheap source of nutrients for humans in most developing countries, including those in sub-Saharan Africa. Breeding for essential quality traits is an important goal of sweetpotato breeding programs. This may include root protein content (RPC), since protein-energy malnutrition is a common problem worldwide. The objective of this study was to quantify the genetic diversity in RPC present among sweetpotato accessions maintained in the genebank of the Agricultural Research Council (ARC) of South Africa in order to characterize and select the most promising clones for breeding. Both, Dumas combustion and Near-infrared Spectroscopy (NIRS) were used to determine RPC for a diverse set of accessions. In addition, total root yield and dry matter content were determined and root flesh colour recorded. Data was subjected to standard analysis of variance. A total of 227 sweetpotato accessions (53 introduced accessions, 18 local cultivars, 24 local landraces and 132 ARC breeding lines) were screened for total RPC, and a large variation was observed. As measured by the Dumas combustion, RPC values varied from 2.65 to 6.45% on a dry weight basis (dwb). RPC estimated by NIRS ranged from 0.68 to 11.51%. The NIRS proved to be an efficient and quick tool that can be useful in sweetpotato breeding programs towards selecting for quality traits such as RPC. A total of 31 medium to high yielding accessions with high, intermediate and low RPC were selected for genetic analysis and breeding for enhanced nutrition. Some promising germplasm included the local informal market cultivar 'Impilo' (orange-fleshed) at 6.18%, and the breeding line '2012-29-4', seed imported from Mozambique, at 6.45%. NIRS values for 'Tanzania' and 'Maria Angola' were promising. The study is one of only a few that provides protein data for a large set of sweetpotato accessions from various parts of the world and is useful for sweetpotato breeding programs. Future work can focus on the determination of the concentrations of individual amino acids. [ABSTRACT FROM AUTHOR]

Orange-fleshed sweet potato (OFSP) is considered the single most successful example of biofortification of a staple crop, and presents a feasible option to address vitamin A deficiency. Though initially promoted as part of a crop-based approach focusing on production and consumption at household level, it evolved into small-scale commercial production, predominantly in Sub-Saharan Africa. This paper reviews OFSP initiatives in relation to the South African food environment and food supply systems, also identifying opportunities for scaling out OFSP in a situation where sweet potato is not eaten as a staple. Current per capita consumption of sweet potato is low; the focus is thus on increasing consumption of OFSP, rather than replacing cream-fleshed varieties. For the major OFSP variety, Bophelo, 66 g consumption can be sufficient to meet the recommended daily allowance for 1–3 year old children (300 μRE vitamin A). Despite a national Vitamin A supplementation programme and fortified staple foods in South Africa, 43.6% of children under 5 years of age were reported to be vitamin A deficient in 2012, indicating a stronger need to promote the consumption of Vitamin A-rich foods, such as OFSP. To increase availability of and access to OFSP, all aspects of the food supply system need to be considered, including agricultural production, trade, food transformation and food retail and provisioning. Currently, small-scale commercial OFSP producers in South Africa prefer to deliver their produce to local informal markets. To enter the formal market, small-scale producers often have difficulties to meet the high standards of the retailers' centralised procurement system in terms of food quality, quantity and safety. Large retailers may have the power to increase the demand of OFSP, not just by improving availability but also by developing marketing strategies to raise awareness of the health benefits of OFSP. However, currently the largest scope for scaling out is through a number of public sector programmes such as the National School Nutrition Programme, Community Nutrition and Development Centres, Small-holder Farmer programmes and Agriparks. Though the major approach is focused on unprocessed, boiled OFSP, there are unexploited opportunities for processing of OFSP. However, the nutritional quality of products should be a main consideration within the context of the co-existence of undernutrition, overnutrition and micronutrient deficiencies in the country. [ABSTRACT FROM AUTHOR]

Objectives: To assess knowledge, perceptions and practices on food production amongst learners and educators, gardening activities and management of school food gardens in schools participating in the National School Nutrition Programme. Design: Cross-sectional survey. Setting: Ten purposively selected primary schools in each of the nine provinces of South Africa (total:n = 90). Subjectsand outcome measures: Questionnaire data were collected from the garden administrators (n = 66), garden workers (n = 55), educators (n = 687) and learners (n = 2 547). A checklist was completed for the school garden (n = 66) by observation. Results: Sixty-six (73%) schools had a food garden, varying in size (100 m2– 6 000 m2). A variety of vegetables, but few fruit, were grown. Problems experienced with gardens were mostly lack of funds (59%), tools and infrastructure (47%), garden workers (53%) and technical support (50%). Few schools received external funding for food gardens. In 50% of gardens, crops were growing for > 6 months, and 30% of gardens provided fresh produce for school meals more than twice a week. Fifty-four percent (54%) of learners were involved in school gardens, and 67% had food gardens at home. Attitudes of learners and educators towards both food gardening and eating vegetables and fruit were generally positive; 68.4% of learners and 86.4% of educators indicated they like to eat vegetables every day. Conclusions: School food gardens as a vehicle for improving nutrition should be strengthened through training of educators and garden personnel, and support by external role players and policy directives are needed to enhance sustainability. [ABSTRACT FROM PUBLISHER]

Background As eating quality is important for adoption of new varieties, nine orange-fleshed and three cream-fleshed sweet potato varieties were assessed for sensory characteristics, dry mass and free sugar content, instrumental texture and colour and consumer acceptability ( n = 216) in a peri-urban South African setting. Results Cream-fleshed varieties were higher in yellow-green colour and sweet potato-like flavour and lower in graininess. Orange-fleshed varieties were higher in pumpkin-like flavour, orange colour, discolouration and sucrose content. Partial least squares regression analysis showed that the most accepted varieties (Impilo, Excel, Resisto, 2001_5_2, Serolane, W-119 and Monate) were associated with sweet flavour, dry mass and maltose content, while the least accepted varieties (Beauregard, Khano and 1999_1_7) were associated with wateriness. Pearson correlation analysis highlighted correlations of sensory attributes yellow and orange with instrumental colour measurements (colour a* and colour b*), instrumental firmness with sensory firmness, dry mass with sensory wateriness, and maltose content with sensory sweet and sweet potato-like flavour. The varieties were clustered into three groups. Consumer acceptability for eating quality correlated with maltose content, dry mass and sweet flavour. Conclusion Chemical and instrumental measurements were identified to evaluate key attributes and will be useful in the intermediate phases of sweet potato varietal development. [ABSTRACT FROM AUTHOR]

Sociodemographic, living standard measure, consumption of vegetables and fruit, and dietary diversity in relation to household food security were assessed. Using a hunger score, households were categorized as food secure (n = 125) or food insecure (n = 273). Food secure respondents had a higher mean dietary diversity score (3.98; 95%CI [3.79, 4.18] versus 3.65; 95% [CI 3.53, 3.77]), were more likely to eat vitamin A–rich foods (OR 1.15; 95% CI [1.05, 1.26]), a more varied diet (DDS ≥ 4, OR 1.90; 95% CI [1.19, 3.13]), and vegetables daily (OR 3.37; 95% CI [2.00, 5.76]). Cost limited daily vegetable/fruit consumption in food insecure households. Respondents with ≥ 8 years of schooling were more likely (OR 2.07; 95% CI [1.22, 3.53]) and households receiving social grants were less likely (OR 0.37; 95% CI [0.19, 0.72]) to be food secure. Results highlight the association between dietary diversity and household food security. [ABSTRACT FROM PUBLISHER]

Near-infrared spectroscopy (NIRS) is an alternative analytical method that can be used to quantify protein content in sweetpotato. It is relatively cheaper and efficient than other methods. This study was conducted to develop NIRS-based models for quantifying protein content of sweetpotato for selection or wide-area production of recommended varieties. A pool of 104 sweetpotato varieties were sampled and roots scanned using NIR spectrometer. Calibration models were developed by subjecting spectral and reference datasets to partial least squares regression. Several pre-processing methods were investigated. Models that yielded the highest coefficient of determination (R 2 ), residual predictive deviation (RPD) and lowest root mean square error of calibration (RMSEC) and prediction (RMSEP) were selected. Optimal model performances were obtained using second derivative pre-processing, showing the highest values of R 2 v , RMSEP and RPD v of 0.98, 0.29, and 4.0, respectively. The regression analysis indicated that informative NIR bands for quantifying protein content of sweetpotatoes ranged between 1600 and 2200 nm. The results demonstrated that NIRS is capable of predicting protein content on sweetpotatoes, rapidly and accurately. Therefore, the NIRS model developed in this study may help to quantify protein composition of sweetpotato for rapid screening of germplasm in breeding programs with high throughput and accuracy. [ABSTRACT FROM AUTHOR]

Sweetpotato (Ipomoea batatas L.(LAM)) is one of the most important food crops in developing countries, including South Africa. Most sweetpotato varieties in South Africa are cream or white fleshed and lack the essential beta-carotene of the orange-fleshed varieties. To develop new varieties with high beta-carotene, knowledge of the genetic variation of the crop is needed. The objectives of this study were to assess the genetic relationships among 30 orange- and cream-fleshed sweetpotato accessions by (i) examining the variation in leaf proteins and (ii) using random amplified polymorphic DNA (RAPD). The polymorphism levels of the proteins and RAPD assays were 55.6% and 98%, respectively. The dendrograms generated from all the analyses clustered the accessions according to their flesh color and country of origin. Analysis of molecular variance (AMOVA) found a significant difference between the South African and non-South African germplasm. The high genetic diversity in the South African sweetpotato germplasm is a positive indicator for a breeding program that has a number of targets, such as breeding for nutritional improvement, disease resistance and drought tolerance. [ABSTRACT FROM AUTHOR]