Sweetpotato Storage Roots Research Articles

A ζ-carotene desaturase gene, IbZDS, increases β-carotene and lutein contents and enhances salt tolerance in transgenic sweetpotato

ζ-Carotene desaturase (ZDS) is one of the key enzymes in carotenoid biosynthesis pathway. However, the ZDS gene has not been applied to carotenoid improvement of plants. Its roles in tolerance to abiotic stresses have not been reported. In this study, the IbZDS gene was isolated from storage roots of sweetpotato (Ipomoea batatas (L.) Lam.) cv. Nongdafu 14. Its overexpression significantly increased β-carotene and lutein contents and enhanced salt tolerance in transgenic sweetpotato (cv. Kokei No. 14) plants. Significant up-regulation of lycopene β-cyclase (β-LCY) and β-carotene hydroxylase (β-CHY) genes and significant down-regulation of lycopene ε-cyclase (ε-LCY) and ε-carotene hydroxylase (ε-CHY) genes were found in the transgenic plants. Abscisic acid (ABA) and proline contents and superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities were significantly increased, whereas malonaldehyde (MDA) content was significantly decreased in the transgenic plants under salt stress. The salt stress-responsive genes encoding pyrroline-5-carboxylate reductase (P5CR), SOD, CAT, ascorbate peroxidase (APX) and POD were found to be significantly up-regulated in the transgenic plants under salt stress. This study indicates that the IbZDS gene has the potential to be applied for improving β-carotene and lutein contents and salt tolerance in sweetpotato and other plants.

First Report of Rhizopus oryzae Causing Soft Rot on Storage Roots of Sweetpotato in China

First Report of <i>Rhizopus oryzae</i> Causing Soft Rot on Storage Roots of Sweetpotato in China

The use of humic acid urea fertilizer for increasing yield and utilization of nitrogen in sweet potato

Humic acid urea fertilizer (HA-N) is a new type of slow-release nitrogenous fertilizer that can enhance utilization rate of urea, and consequently increases crop yield. However, there were few researches about the effect of HA-N on the nitrogen absorption and utilization in sweet potato production. Hence, the effect of HA-N on nitrogen accumulation and distribution, nitrogen use efficiency (NUE), and yield of sweet potato was studied in the field using the &lt;sup&gt;15&lt;/sup&gt;N tracer technique. Results showed that HA-N significantly increased the number of storage roots per plant and the average fresh weight per storage root, as well as the yield increased by 29.6% compared with urea fertilizer. Furthermore, nitrogen accumulation of total plant was higher under the HA-N. In addition, HA-N significantly increased nitrogen production efficiency of fertilizer and nitrogen production efficiency. Results of a &lt;sup&gt;15&lt;/sup&gt;N tracer experiment revealed that the percentage of nitrogen absorbed by plant from fertilizer increased from 31.1% to 38.7% and NUE increased from 33.5% to 44.8% with application of HA-N when compared with single N treatment, respectively. HA-N significantly increased sweet potato storage root yield, nitrogen absorption and NUE, as well as it reduced the loss of nitrogen fertilizer.

Functional Classification of Skinning Injury Responsive Genes in Storage Roots of Sweetpotato

Skinning injury in sweetpotato due to loss of skin or periderm which occurred during harvest is inevitable and account for financial loss due to dehydration, pests, and pathogens. Hence, studies on gene expression changed due to skinning injury can provide important information about this protective tissue and for improving the life of storage roots. New candidate genes involved in skinning injury were isolated with an Annealing Control Primer (ACP). Using 20 ACP primers, a total of 103 differentially expressed genes (DEGs) were retrieved. In this study, the functional annotation of these selected 15 up-regulated DEGs (10 contigs and 5 singletons) were characterized. The results showed that these 15 “DEG-unigenes” are mainly associated with defense and stress responses, regulation and signaling, protein synthesis and fate, and metabolism may play an important role in the primary responses to skinning injury in storage roots of sweetpotato. This study showed the importance of defense and stress responses genes to the formation of wound periderm. Furthermore, this results can be used for better understanding of the molecular mechanism of skinning/mechanical injury-related genes in the storage roots of sweetpotato as well as to all stems, fruits, and roots of all plants. Keywords: differentially expressed gene, gene function, Ipomoea batatas, wounding

Plastidial α-glucan phosphorylase 1 complexes with disproportionating enzyme 1 in Ipomoea batatas storage roots for elevating malto-oligosaccharide metabolism.

It has been proposed that malto-oligosaccharides (MOSs) are possibly recycled back into amylopectin biosynthesis via the sequential reactions catalyzed by plastidial α-glucan phosphorylase 1 (Pho1) and disproportionating enzyme 1 (Dpe1). In the present study, the reciprocal co-immunoprecipitation experiments using specific antibodies against Pho1 and Dpe1 demonstrated that these two enzymes can form a complex (the PD complex) in Ipomoea batatas storage roots. The immunohistochemistry analyses also revealed the co-localization of Pho1 and Dpe1 in the amyloplasts, and the protein levels of Pho1 and Dpe1 increased gradually throughout sweet potato storage root development. A high molecular weight PD complex was co-purified from sweet potato storage root lysates by size exclusion chromatography. Enzyme kinetic analyses showed that the PD complex can catalyze maltotriose and maltotetraose to generate glucose-1-phosphate in the presence of inorganic phosphate, and it also performs greater Dpe1 activity toward MOSs than does free form Dpe1. These data suggest that Pho1 and Dpe1 may form a metabolon complex, which provides elevated metabolic fluxes for MOS metabolism via a direct transfer of sugar intermediates, resulting in recycling of glucosyl units back into amylopectin biosynthesis more efficiently.

The use of humic acid urea fertilizer for increasing yield and utilization of nitrogen in sweet potato

Humic acid urea fertilizer (HA-N) is a new type of slow-release nitrogenous fertilizer that can enhance utilization rate of urea, and consequently increases crop yield. However, there were few researches about the effect of HA-N on the nitrogen absorption and utilization in sweet potato production. Hence, the effect of HA-N on nitrogen accumulation and distribution, nitrogen use efficiency (NUE), and yield of sweet potato was studied in the field using the &lt;sup&gt;15&lt;/sup&gt;N tracer technique. Results showed that HA-N significantly increased the number of storage roots per plant and the average fresh weight per storage root, as well as the yield increased by 29.6% compared with urea fertilizer. Furthermore, nitrogen accumulation of total plant was higher under the HA-N. In addition, HA-N significantly increased nitrogen production efficiency of fertilizer and nitrogen production efficiency. Results of a &lt;sup&gt;15&lt;/sup&gt;N tracer experiment revealed that the percentage of nitrogen absorbed by plant from fertilizer increased from 31.1% to 38.7% and NUE increased from 33.5% to 44.8% with application of HA-N when compared with single N treatment, respectively. HA-N significantly increased sweet potato storage root yield, nitrogen absorption and NUE, as well as it reduced the loss of nitrogen fertilizer.

RESPONSE OF SWEET POTATO PLANT TO THE SAME SOURCES OF ORGANIC MANURE AND APPLICATION METHODS OF POTASSIUM HUMATE UNDER SANDY SOIL CONDITIONS.

Two field experiments were performed during two consecutive summer seasons of 2014 and 2015 at El-Kassasien Hort. Res. Station, Ismailia Governorate, Egypt, to study the effect of organic manure sources (recommended chemical fertilizers, FYM, compost and chicken manure) and potassium humate ( without, soil application and foliar application) at the rate of 2 g/L ,as well as, different combination between them on plant growth, chemical constituents, yield and its components and storage root quality of sweet potato (Ipomoea batatas, L.) cv. Abees grown under sandy soil condition with drip irrigation system. Application of organic manure fertilizers caused significant increases in growth parameter, yield and its components and mineral contents compared to control treatment (without organic fertilization). meanwhile, application of chicken manure at the rate of 5 m3/fed. achieved highest values of all aforementioned parameters, followed by the application of compost at the rate of 15 m3/fed and FYM at the rate of 15 m3/fed, in a descending order, respectively. Spraying sweet potato plants with potassium humate significantly enhanced plant growth, yield and its components and mineral contents (NPK content in tuber root TSS, reducing and total sugar as well as total carbohydrate contents). In this respect, spraying plants with 2 g/L potassium humate attained the superiority impacts comparing the other treatments. Hence, it can be concluded that fertilizing sweet potato plants by chicken manure at the rate of 5 m3/fed. in combined with spraying plants by potassium humate at the rate of2 g/L gave the highest values of growth, yield and its components and chemical constituents as compared to other interaction treatments. Conclusively, this study showed that the highest yield of sweet potato storage roots and storage roots quality were obtained from chicken manure at 5 m3/fed., foliar application was potassium humate (2 g/L). The interaction between 5 m3 chicken manure and potassium humate as foliar application at the rate of2 g/L.

Metabolic engineering of carotenoids in transgenic sweetpotato.

Sweetpotato [Ipomoea batatas (L.) Lam], which contains high levels of antioxidants such as ascorbate and carotenoids in its storage root, is one of the healthiest foods, as well as one of the best starch crops for growth on marginal lands. In plants, carotenoid pigments are involved in light harvesting for photosynthesis and are also essential for photo-protection against excess light. As dietary antioxidants in humans, these compounds benefit health by alleviating aging-related diseases. The storage root of sweetpotato is a good source of both carotenoids and carbohydrates for human consumption. Therefore, metabolic engineering of sweetpotato to increase the content of useful carotenoids represents an important agricultural goal. This effort has been facilitated by cloning of most of the carotenoid biosynthetic genes, as well as the Orange gene involved in carotenoid accumulation. In this review, we describe our current understanding of the regulation of biosynthesis, accumulation and catabolism of carotenoids in sweetpotato. A deeper understanding of these topics should contribute to development of new sweetpotato cultivars with higher levels of nutritional carotenoids and abiotic stress tolerance.

Carbohydrate components in sweetpotato storage roots: their diversities and genetic improvement.

Carbohydrates are important components in sweetpotatoes in terms of both their industrial use and eating quality. Although there has been a narrow range of diversity in the properties of sweetpotato starch, unique varieties and experimental lines with different starch traits have been produced recently both by conventional breeding and genetic engineering. The diversity in maltose content, free sugar composition and textural properties in sweetpotato cultivars is also important for their eating quality and processing of storage roots. In this review, we summarize the current status of research on and breeding for these important traits and discuss the future prospects for research in this area.

Sweetpotato Response to Simulated Glyphosate Wick Drip

Field studies were conducted in 2009 at Clinton, NC and 2014 at Pontotoc, MS to determine the influence of simulated glyphosate drip on sweetpotato yield and quality. Treatments consisted of three glyphosate solution (140 g ae L–1) drip volumes (0.16, 0.32 and 0.48 ml) by four application timings [(4 wk after transplanting (WAP); 6 WAP; 8 WAP; and 4 WAP followed by (fb) 6 WAP fb 8 WAP]. A non-treated check was included for comparison. Visual sweetpotato injury consisted of chlorosis at the shoot tips approximately 1 wk after treatment fb necrosis and stunting. At 6 WAP and 8 WAP, sweetpotato injury following glyphosate applied 4 WAP was 71 and 65%, respectively. Injury from glyphosate applied 4 WAP fb 6 WAP was 78%. Injury from glyphosate applied 6 WAP was 26% at 8 WAP. In 2009, jumbo, no. 1, canner, and marketable yield of the non-treated check were two to three times greater than glyphosate treatments (0.16, 0.32, 0.48 ml). Likewise, yield of the non-treated check was substantially greater than those treated with 0.16 to 0.48 ml glyphosate solution in 2014. In 2009 and 2014, sweetpotato yield of all grades increased as glyphosate application timing was delayed. In 2009, no. 1 yield from glyphosate 8 WAP (8,210 kg ha–1) was similar to the non-treated check. In 2009, there were no cracked storage roots in the non-treated check. However, sweetpotatoes receiving 0.16 to 0.48 ml glyphosate solution displayed 8 to 17%, 11 to 18%, 5 to 13%, and 11 to 16% cracking (by weight) in jumbo, no. 1, canner, and marketable storage roots, respectively. Compared to the non-treated check, glyphosate applied 4 WAP, 6 WAP, or 4 WAP fb 6 WAP fb 8 WAP had a greater percentage of cracked marketable sweetpotato storage roots.

Factors Affecting Greenhouse Sweetpotato Slip Production

ABSTRACTSweetpotato certified seed producers rely on fast propagation of virus-indexed slip plants in the greenhouse to obtain transplants for the production of first generation of storage roots. Effective fertilization is important for greenhouse vegetative propagation, but relevant guidelines are rare. Greenhouse experiments were conducted in 2011 and 2012 using sweetpotato (Ipomoea batatas (L.) Lam.) var. Covington, Beauregard, and Evangeline to evaluate effects of fertilizer rate on slip production. The most commonly used commercial fertilizer mix (20N–10P–20K) was applied at the rates 50, 100, 200, 300, 400 mg·L−1 of N. Plants were harvested nine times over the season in both years. Total nodes on vines and total slip fresh weight were determined. ‘Evangeline’ produced more nodes—that is, more plants—than ‘Beauregard’ and ‘Covington’, and ‘Beauregard’ produced the highest slip fresh weight, followed by ‘Evangeline’ and ‘Covington’. Effect of fertilizer rate on vine node count was similar for early (harvests 1–3) and middle harvests (harvests 4–6) but impacted late harvests (harvests 7–9), where fertilizer rates from 100 to 300 mg·L−1 of N resulted in similar number of plant nodes, and 50 and 400 mg·L−1 of N reduced node count. Undesirable storage root formation in pots was favored by 50 mg·L−1 of N fertilizer rate, whereas fertilizer at or above 100 mg·L−1 of N inhibited them. ‘Covington’ produced the most storage roots. Fertilizer rate during slip production in the greenhouse did not affect transplant stand count in the field and subsequent field production of sweetpotato storage roots. The commercial fertilizer 20N-10P-20K should be applied from 100 to 200 mg·L−1 of N to produce the most slips and least storage roots in greenhouse pots.

Self-preserving lognormal volume-size distributions of starch granules in developing sweetpotatoes and modulation of their scale parameters by a starch synthase II (SSII)

Starch granule size distributions in plant tissues, when determined in high resolution and specified properly as a frequency function, could provide useful information on the granule formation and growth. To better understand genetic control of physical properties of starch granules, we attempted a new approach to analyze developmental and genotypic effects on morphology and size distributions of starch granules in sweetpotato storage roots. Starch granules in sweetpotatoes exhibited low sphericity, many shapes that appeared to be independent of genotypes or developmental stages, and non-randomly distributed sizes. Granule size distributions of sweetpotato starches were determined in high resolution as differential volume-percentage distributions of volume-equivalent spherical diameters, rigorously curve-fitted to be lognormal, and specified using their geometric means $$\bar{x}^{*}$$ and multiplicative standard deviations $$s^{*}$$ in a $$\bar{x}^{*} \times /({\text{multiply/divide}})s^{*}$$ form. The scale ( $$\bar{x}^{*}$$ ) and shape ( $$\bar{s}^{*}$$ ) of these distributions were independently variable, ranging from 14.02 to 19.36 μm and 1.403 to 1.567, respectively, among 22 cultivars/clones. The shape ( $$s^{*}$$ ) of granule lognormal volume-size distributions of sweetpotato starch were found to be highly significantly and inversely correlated with their apparent amylose contents. More importantly, granule lognormal volume-size distributions of starches in developing sweetpotatoes displayed the same self-preserving kinetics, i.e., preserving the shape but shifting upward the scale, as those of particles undergoing agglomeration, which strongly indicated involvement of agglomeration in the formation and growth of starch granules. Furthermore, QTL analysis of a segregating null allele at one of three homoeologous starch synthase II loci in a reciprocal-cross population, which was identified through profiling starch granule-bound proteins in sweetpotatoes of diverse genotypes, showed that the locus is a QTL modulating the scale of granule volume-size distributions of starch in sweetpotatoes.

Genetic control of dry matter, starch and sugar content in sweetpotato

ABSTRACTSweetpotato (Ipomoea batatas L. (Lam)) is a nutritious food security crop for most tropical households, but its utilisation is very low in Ghana compared to the other root and tuber crops due to lack of end-user-preferred cultivars. Knowledge on the genetic control of important traits such as dry matter, starch and sugar content of sweetpotato storage roots in a breeding population is critical for making breeding progress in developing sweetpotato varieties preferred by farmers and consumers. This study used diallel mating design to elucidate general combining ability and specific combining ability, to determine the gene action controlling storage root dry matter, starch and sugar content in sweetpotato and the heterotic potential of the traits to facilitate the crop’s improvement for increased utilisation. A general model for estimating genetic effects, GEAN II, was used to analyse the data. Genetic variability was seen for dry matter, starch and sugar content of sweetpotato and much of this genetic variation was additive in nature. The study also revealed significant heterosis in sweetpotato which offers opportunity for breeding non-sweet, high dry matter sweetpotato varieties that are preferred by farmers and consumers in Ghana.

Genetic Bottlenecks for Two Populations of Ceratocystis fimbriata on Sweet Potato and Pomegranate in China.

Chinese isolates of Ceratocystis fimbriata from sweet potato (Ipomoea batatas) and pomegranate (Punica granatum) were genetically compared with a worldwide collection of isolates from a variety of hosts. Isolates from black-rotted storage roots of sweet potato in China, Japan, Australasia, and the United States had identical internal transcribed spacer (ITS) ribosomal DNA (rDNA) sequences and only minor variation in microsatellite alleles. Sequences of their mating type genes were most similar to those of isolates from various hosts in Ecuador, a center of diversity for sweet potato. Isolates from Colocasia esculenta (taro) and pomegranate from Yunnan and Sichuan had only one ITS rDNA sequence (haplotype ITS5). This haplotype, sequences of mating type genes, and microsatellite alleles linked these isolates to isolates from Eucalyptus stumps in South China and diseased Eucalyptus trees in Brazil, supporting the hypothesis that the pomegranate population originated from Brazil via cuttings of Eucalyptus. Isolates from sweet potato and pomegranate in China were interfertile with tester strains of C. fimbriata, confirming that the causes of the two epidemics in China belong to a single biological species. However, other isolates from Eucalyptus stumps were intersterile with the tester strains and had ITS rDNA sequences typical of the Asian species, C. cercfabiensis.

Purple Sweet Potato Anthocyanin Inhibits the Proliferation of Human Retinal Pigment Epithelial Cell by Blocking Cell Cycle and Inducing Apoptosis

Purple Sweet Potato Anthocyanin (PSPA), a class of naturally occurring anthocyanins derived from purple sweet potato storage roots, possesses unique color and multiple bioactivities. This study investigated the anti-proliferative effect of PSPA in human Retinal Pigment Epithelial (RPE) cells, the proliferation of which accounts for Proliferative Vitreoretinopathy (PVR). Blueberry Anthocyanin (BBA) was used as a contrast. PSPA and BBA inhibited RPE proliferation time-and dose-dependently through blocking the cell cycle in G0/G1 phase and inducing apoptosis via ROS accumulation, DNA damage and caspase 3/7 activation. Meanwhile, PSPA showed stronger potential than BBA in inhibiting RPE growth. Hence, we highlighted the importance of dietary supplementation of anthocyanins in PVR prevention and the application of PSPA in health industry.

Effects of Transplanting and Harvesting Dates on Characteristics of Yield and Quality of Storage Roots of Sweetpotato (Ipomoea batatas (L.) Lam)

Effects of Transplanting and Harvesting Dates on Characteristics of Yield and Quality of Storage Roots of Sweetpotato (Ipomoea batatas (L.) Lam)

Effects of ethylene and 1-methylcyclopropene on sweetpotato storage root quality

Effects of ethylene and 1-methylcyclopropene on sweetpotato storage root quality

Development and Identification of SSR Markers Associated with Starch Properties and β-Carotene Content in the Storage Root of Sweet Potato (Ipomoea batatas L.).

Sweet potato (Ipomoea batatas L.) is a nutritious food crop and, based on the high starch content of its storage root, a potential bioethanol feedstock. Enhancing the nutritional value and starch quantity of storage roots are important goals of sweet potato breeding programs aimed at developing improved varieties for direct consumption, processing, and industrial uses. However, developing improved lines of sweet potato is challenging due to the genetic complexity of this plant and the lack of genome information. Short sequence repeat (SSR) markers are powerful molecular tools for tracking important loci in crops and for molecular-based breeding strategies; however, few SSR markers and marker-trait associations have hitherto been identified in sweet potato. In this study, we identified 1824 SSRs by using a de novo assembly of publicly available ESTs and mRNAs in sweet potato, and designed 1476 primer pairs based on SSR-containing sequences. We mapped 214 pairs of primers in a natural population comprised of 239 germplasms, and identified 1278 alleles with an average of 5.972 alleles per locus and a major allele frequency of 0.7702. Population structure analysis revealed two subpopulations in this panel of germplasms, and phenotypic characterization demonstrated that this panel is suitable for association mapping of starch-related traits. We identified 32, 16, and 17 SSR markers associated with starch content, β-carotene content, and starch composition in the storage root, respectively, using association analysis and further evaluation of a subset of sweet potato genotypes with various characteristics. The SSR markers identified here can be used to select varieties with desired traits and to investigate the genetic mechanism underlying starch and carotenoid formation in the starchy roots of sweet potato.

Effect of Different Storage Methods and Fertilizer Rates on Quality of Sweetpotato (Ipomoea batatas L.) Storage Roots

Effect of Different Storage Methods and Fertilizer Rates on Quality of Sweetpotato (Ipomoea batatas L.) Storage Roots

Isolation and analysis of the promoter of IbMYB1 gene from storage roots of purple-fleshed sweet potato

In purple-fleshed sweet potato, transcription factors were isolated such as IbMADS10, IbMYB and WD40. IbMYB1 activates the expression of the structural anthocyanin genes and controls anthocyanin biosynthesis specifically in the flesh of storage roots. However, the mechanisms controlling IbMYB1 in underground organs remain unresolved. A 1186-bp promoter sequence of IbMYB1 by hiTAIL-PCR was isolated, the cis-regulatory elements of the promoter sequence were analyzed by using the PLACE and PlantCARE databases. Many cis-regulatory elements associated with sucrose, gibberellins and light were found in the promoter region, such as, SURE1STPAT21, WBOXHVISO1, PYRIMIDINEBOXHVEPB1 and WRKY71OS. The results from GUS histochemical staining indicated that the promoter drove the expression of the reporter gene and induced constitutive GUS expression in all tissues throughout the growth period. The IbMYB1 promoter responses to sucrose, methyl jasmonate and gibberellins treatments. It was obviously up-regulated by 100 μM methyl jasmonate treatment. These results suggest that the ability of plant hormones to modulate the anthocyanin biosynthetic pathway is highly dependent on the IbMYB1 promoter.