Metabolic profiles and morphological characteristics of leaf tips among different sweet potato(Ipomoea batatas Lam.)varieties

Sweet potato leaf tips have high nutritional value,and exploring the differences in the metabolic profiles of leaf tips among different sweet potato varieties can provide information to improve their qualities.In this study,a UPLC-Q-Exactive Orbitrap/MS-based untargeted metabolomics method was used to evaluate the metabolites in leaf tips of 32 sweet potato varieties.Three varieties with distinct overall metabolic profiles(A01,A02,and A03),two varieties with distinct profiles of phenolic acids(A20 and A18),and three varieties with distinct profiles of flavonoids(A05,A12,and A16)were identified.In addition,a total of 163 and 29 differentially expressed metabolites correlated with the color and leaf shape of sweet potato leaf tips,respectively,were identified through morphological characterization.Group comparison analysis of the phenotypic traits and a metabolite-phenotypic trait correlation analysis indicated that the color differences of sweet potato leaf tips were markedly associated with flavonoids.Also,the level of polyphenols was correlated with the leaf shape of sweet potato leaf tips,with lobed leaf types having higher levels of polyphenols than the entire leaf types.The findings on the metabolic profiles and differentially expressed metabolites associated with the morphology of sweet potato leaf tips can provide useful information for breeding sweet potato varieties with higher nutritional value.

Highβ-sitosterol-D-glucoside content in sweet potato varieties and its anti-breast cancer potential through multiple metastasis-associated signals

β-Sitosterol-D-glucoside(β-SDG)is a phytosterol compound whose antitumor activity has been confirmed by previous studies.However,its suppression on breast cancer remains unclear.To that purpose,we isolatedβ-SDG from sweet potato and investigated the breast-cancer-inhibiting mechanism using proteomic analysis.The sweet potato species S6 with highβ-SDG content were chosen form 36 species andβ-SDG was isolated by HPLC.Afterwards,an in situ animal model of breast cancer was established,andβ-SDG significantly reduced the tumor volume of MCF-7 xenograft mice.Proteomic analysis of tumor tissues revealed that 127 of these proteins were upregulated and 80 were downregulated.Gene ontology and network analysis showed that regulatory proteins were mainly associated with epithelial-mesenchymal transition(EMT),myogenesis,cholesterol homeostasis,oxidative phosphorylation and reactive oxygen pathways,while Vimentin,NDUF,VDAC1,PPP2CA and SNx9 were the most significant 5 node degree genes.Meanwhile,in vitro and in vivo results showed that the protein expression of PPP2CA and Vimentin,which are markers of EMT,were involved in breast cancer cell metastasis and could be reversed byβ-SDG.This work highlightsβ-SDG as a bioactive compound in sweet potato and the potential therapeutic effect ofβ-SDG for the treatment of breast cancer by inhibiting metastasis.

Influence of Sanitization Process on Maintaining Sweet Potato Quality for Export

The whole cold-chain for exporting sweet potato(native variety“Abees”),to foreign market included immediate curing operation directly after harvest helped in healing skin texture,however,in order to reduce postharvest soft rot(Rhizopus stolonifer)incidence following trimming,and washing,ultraviolet light(UV-C)treatment was used as a main sanitizer for eliminating the soft rot.Exposure of the roots to UV-C(254 nm)was applied in a UV-C room on freshly harvested and cured sweet potato while rolling up on a movable line at 20 cm distance for 1,2,and 3 hr.As combining UV-C treatment with chlorine(200 ppm)on roots,marked and significant reduction of the total microbial load and Rhizopus potential was achieved on root surfaces respectively compared with chlorine alone.It also reduced soft rot percentage to almost 0%infection.After 3 months of cold-storage,quality assessment of sweet potato showed that root characteristics were markedly maintained.The ability of UV-C light to induce phenylalanine ammonia lyase(PAL)enzyme activity in root tissue and maintain the activities of peroxidase and polyphenol oxidase,however with slight increase,was detected.UV-C caused an increase of phenol content in sweet potato tissue that made an activation of defense reaction against the rot causal pathogen.As the exposure time to UV-C light increased,a higher content of phenols occurred.Moreover,UV-C application caused decrease in sugar content of root tissue that is flavored by soft rot-causal pathogen.

Effect of Size and Initial Water Content on the Effective Diffusion Coefficient during Convective Drying of Sweet Potato Cut into Cubic and Cylindrical Shapes

In this article, we investigated the influence of size and initial water content on the effective diffusion coefficient of sweet potatoes samples cut into cubic and cylindrical shapes. The sizes of the cubic samples are 0.5, 1, 1.5, 1.75, 2, 2.5 and 3 cm edge with a respective initial water content of 2.7, 3.76, 3.48, 2.68, 3.28, 2.17 and 2.29 kg/kgms. For cylindrical samples, the radius is set at 0.5 cm and sample heights are 1, 1.5, 2, 2.5, 3, 3.5 and 4 cm with respective water contents of 2.2, 3.19, 2.85, 2.1, 2.17, 2.39 and 2.03 kg/kgms. The effective diffusion coefficients of cubic samples are of the order of 10−10 and 10−9 m2∙s−1 grew with sample edge. As for the cylindrical samples, the effective diffusion coefficients were of the order of 10−9 m2∙s−1 and there was no linear correlation between cylinder height and their effective diffusion coefficient. As for the examination of the initial water content on the effective diffusion coefficient, it turned out that the initial water content had no influence on the effective diffusion coefficient of the sweet potato samples.

Effects of Sodium Chloride Stress on Growth of Sweet Potato Plantlets in vitro and Ion Content

[Objective] This study aimed to investigate the salt-tolerance mechanism of sweet potato.[Method]Two sweet potato varieties of Xu 25-2(salt-tolerant cultivar)and Triumph 100(salt-sensitive cultivar)were treated by sodium chloride with the concentration of 0 mmol/L and 100 mmol/L.After 20 days,Na+ content and Na+/K+ ratio in the roots,shoots and leave were determined by the flame photometer,while dry weight and fresh weight of roots,shoots and leave in different varieties were also studied.[Result]The growth of two sweet potato varieties was inhibited under salt stress,so the plant became shorter,leaf and root became fewer,dry weight of roots and leave decreased,but seedlings of Xu 25-2 were inhibited slightly.Furthermore,Na+ content and Na+/K+ ratio in roots,shoots and leaves of two sweet potato varieties increased.Na+ content of salt-tolerant Xu 25-2 was low in roots,shoots and leaves,while Na+ content of salt-sensitive Triumph 100 was high in shoots and leave of seedlings,but the change range of Xu 25-2 was less than that of Triumph 100.[Conclusion]The lower Na+ content and Na+/K+ ratio in leaves under salt stress were the most important characteristics for salt-tolerance of sweet potato varieties.

Effects of Planting Density on Yield and Sourcesink Characteristics of Sweet Potato[Ipomoea batatas(L.) Lam]

[Objective] The aim was to resolve the issue of sparsely planting （37 500-40 500 plants/hm2） of sweet potato in hilly areas. [Method] The starch-oriented Jishu No.21 and raw-eating oriented Jishu No.22 were studied to explore effects of planting density on yield and sink and source characteristics of sweet potato. [IRe- suit] Leaf area index of Jishu No.21 and Jishu No.22 were increasing upon planting density. Leaf area index of the same planting density showed a single-peak curve. Specifically, leaf area index grew fast during the 40th-80th d after planting, and reached the peak on the 80th d after planting, followed by decreasing. What＇s more, ventilation and sunshine transmission both declined upon planting density, as well as the number of leaf, the number of branch, the length of vine, dry and fresh weights of stem and leaf. When planting density exceeded 75 000 plants/hm2, the yield of sweet potato dropped dramatically. Besides, the optimal planting density tended to be volatile upon cultivars. For example, the range of 45 000-60 000 plants/hm2 is the optimal planting density of Jishu No.21 and the range of 60 000-75 000 plants/hm2 is the optimal planting density of Jishu No.22. [Conclusion] It can be concluded that rational planting densities would well coordinate sweet potato growth of ground parts and underground parts to get a high yield by providing a rational group structure. Considering the optimal planting density differs upon cultivars, it is necessary to take genotype, environment, soil fertility and planting density into consideration in determining planting density.

Extraction Storage and Qualitative Analysis of Free Radicals Scavenging Substances from Sweet Potato Leaves

[ Objective ] The research aimed to provide reference for the application of extracts from sweet potato leaves in anti-aging cosmetics. [ Method ] The extraction and storage conditions for free radicals scavenging substances from sweet potato leaves were optimized by orthogonal test and the bioactive components in extracts were investigated by correlation analysis. [ Result] Sweet potato leaves contain the bioactive substances scavenging DPPH free radical and hydroxyl free radical. Extracting solvent species is the most important factor that influencing extraction yield. The optimal extraction and storage conditions are as following： water as solvent, pH 8.0 of extracting liquid, storage at 25 ℃. There is a good positive linear relationship between the content of total phenols in sweet potato leaves and corresponding scavenging rates against both the DPPH free radical and hydroxyl free radical. For the content of total flavones in sweet potato leaves, just a correlation with scavenging rate against hydroxyl free radical shown in test. [ Conclusion] The phenols in ex- tracts could effectively scavenge both the DPPH free radical and hydroxyl free radical, whereas the flavones in extracts can only function on the hydroxyl free radical.

Review on hygienical components of sweet potato and their functions

Sweet potato not only contains primary materials such as dietary fiber, vitamin and soluble protein, but also provides abundant secondary metabolic products which have hygienical functions, like caffeic acid and caffeoylqinic acid derivatives, and anthocyanins, carotanoids. Many studies showed that many secondary products of sweet potato have hygienical functions as quenching free radicals, antioxidation, and preventing cancer, cardiovascular disease and diabetes. Further understanding of the hygienical functions of components in sweet potato is considered to be one of the important factors for developing new uses of sweet potato.

Effects of Plastic Film Mulching on Physical Characters of Soil and Yield and Yield Components of Sweet Potato

Field experiments were carried out to study the effects of plastic film mulching on soil physical characters, including soil temperature, soil moisture content and soil bulk density, and yield and yield components of sweet potato. The results showed that plastic filming mulching increased soil temperature. Considering the soil temperature-increasing effect, the treatments ranked as black plastic film treatment 〉 white plastic film treatment 〉 control. However, with the deepening of soil layer, the warming effect of plastic film mulching was weakened. Black or white plastic film mulching was conducive to low T/R value, especially in the early growth stage of sweet potato. Plastic film mulching significantly improved the storage root yield of sweet potato. In terms of yield-improving effect, the treatments ranked as black plastic film treatment 〉 white plastic film treatment 〉 control. The storage root num- ber per plant showed a downward trend, but the weight of single storage root was increased.

The Content Variations of Main Nutrients in Storage Root Expanding Stages of Sweet Potato and Their Mutual Relationships

[Objective] The content variations of the main nutrients in storage root during expanding stages and their mutual relationships in orange-fleshed sweet pota-to （Ipomoea Batatas（L.） Lam） were studied in this paper. [Method] The dynamics of main nutritional ingredients in orange-fleshed sweet potato-variety at 40, 70, 100 and 125 days after transplanting were investigated, and these traits included the 6- carotene content, Fe content, Zn content, starch content, protein content, glucose content, fructose content, and sucrose content. The relationships among these nutri- ents were analyzed during whole developing stage. [Result] B-carotene content in the whole growth period showed straightly increasing firstly, and then decreasing trend, which was unimodal fluctuation curve. The variation tendency of protein con- tent was gently decreasing firstly and then ascending. The dynamics of starch con- tent was similar to l^carotene content, while the fluctuation was stable. The chang- ing curve of carbohydrate was opposite to starch, showing decreasing firstly and then ascending. Fe content was decreasing all the whole developing stage, falling fast and then slowing down. Moreover, Zn content was plummeting. The sucrose content in fresh storage root had significantly negative correlation with β-carotene content, and had positive correlation with fructose content. Starch content had significantly negative correlation with fructose content, and had positive correlation with Zn content. [Conclusion] These research conclusions could guide the variety to har- vest at suitable time, so as to achieve the aim of micronutrition improvement.

Research Advance on Molecular Mechanism of Abiotic and Biotic Stress Resistance in Sweet Potato

Sweet potato（Ipomoea batatas） is not only an important food crop, but also an important economic crop and energy crop. In recent years, as the develop- ment of molecular biology techniques, more and more abiotic and biotic stress-related genes were discovered in sweet potato. These genes can be divided into two categories： the regulatory genes and the functional genes, according to their different roles in stress pathways. This paper reviews the abiotic and biotic stress-related genes cloning, functional analysis and exogenous genes application in sweet potato, and makes expectation for stress resistance research of sweet potato in the future.

Cloning and Analysis of NBS-LRR Type Resistance Gene Analogues in Sweet Potato (Ipomoea batatas)

The degenerate primers were designed based on the conserved NBS-LRR motifs among the known disease-resistance genes. A fragment of about 500 bp was amplified from genomic DNA of sweet potato using the specifically designed degenerate primers. After cloning and sequencing, 20 NBS-LRR type of disease-resistance gene analogue （RGAs） in sweet potato were observed. The deduced amino acid sequence of DNA fragment contains the conserved motifs of NBS-LRR type RGAs, such as P-loop, Kinase-2α, Kinase-3α and GLPL domain. The 20 RGAs could be sorted into two subclasses, namely TIR- NBS-LRR type and non-TIR-NBS-LRR type. Compared with the known resistance genes including N, L6 and M, the percentages of homologous amino acid sequence in 10 TIR-NBS-LRR range between 21% -44%. While other 10 non-TIR-NBS-LRR assume 15% -46% homology with the known resistance genes （Prf, RPM1, RPS2, etc. ）. Consequently the RGAs may further be used as molecular marker for screening the candidate disease-resistance genes in sweet potato.

Extraction Characteristics of Anthocyanins from Preliminarily-processed Products of Purple Sweet Potatoes during the Gelatinization Process

Objective] This study aimed to investigate the method for efficient utilization and development of purple sweet potatoes. [Method] Purple sweet potatoes were dried at two specific temperatures and prepared into preliminarily-processed products for gelatinization simulation to analyze the extraction amount of anthocyanins from gelatinized samples at different gelatinization stages. [Result] During the gelatinization process, the extraction rate of anthocyanins from purple sweet potato samples reached the highest as the temperature rised from 90 ℃ to 95 ℃,and the extraction amount of anthocyanins reached the maximum at 15 min postheat preservation at 95 ℃. Purple sweet potato samples dried at 60 ℃ exhibited larger retention amount, larger maximum extraction amount and higher maximum extraction rate of anthocyanins compared with those dried at 110 ℃. [Conclusion] Drying at low temperatures and appropriately shortening the initial gelatinization stage below 90 ℃ is conducive to the retention and extraction of anthocyanins from purple sweet potatoes.

Species and Occurrence of Scarab in Sweet Potato Growing Areas of Xuzhou,Jiangsu

Frequency-vibrancy pest-killing lamp was used to calculate the numbers and types of scarabs during the growing period of sweet potato in Xuzhou area, thus to study the occurrence regularity of scarab and effect of meteorological factor on its occurrence, which provided a reference and guidance for the control of grub in sweet potato field. The monitoring results indicated that scarabs in sweet potato planting area of Xuzhou mainly included Anomala corpulenta, Holotrichia parallela Motschulsky, Maladera verticalis and Holotrichia trichophora Fairm. Holotrichia tri- chophora Fairm has entered into its late stage at the early cultivation stage of sweet potato with a few occurrence quantities. The elongation stage of sweet potato vine is the full incidence period of imagoes of Maladera verticalis and Anomala cor- pulenta. Full incidence period of Holotrichia parallela Motschulsky is from late June to middle August, the outbreak cycle of which is long. The unearthed imagoes fol- low the regular change ＂many-few-many-few＂. Effects of meteorological factor on the activities of various scarabs are different. The activities of various scarabs are fre- quent in warm and windless sunny days. In rainy days, Holotrichia parallela Motschulsky, Holotrichia trichophora Fairm and Maladera verticalis are inactive. The numbers of Anomala corpulenta in cloudy days but not rainy days are higher than that in sunny days.

Screening and Evaluation of Different Purple Sweet Potato Varieties Specially Used for Processing

Objective] This study almed to screen high-quality and high-yield purpIe sweet potato varieties special y used for processing which were suitabIe for pIanting in Liancheng County. [Method] By using a randomized bIock design, with ‘Longyan 7-3’ as a controI, five purpIe sweet potato varieties were introduced in the autumn of 2012 for comparaton test to evaluate agronomic tralts, economic characters, nu-tritional quality, and processing quantity of dried sweet potato products and fried chips. [Result] ‘Weixiang No.1’ exhibited the highest yield of 41.9 t/hm2, which was improved by 25.8% compared with ‘Longyan 7-3’; fresh tuber yield of ‘Jishu No. 18’ reached 31.6 t/hm2, which was simiIar to that of ‘Longyan 7-3’; dried sweet potato products of ‘Jishu No.18’ and ‘Weixiang No.1’ not onIy had simiIar process stabiIity, taste and coIor to ‘Longyan 7-3’, but also exhibited exceI ent morphoIogy, coIor, transparency, taste and texture, which indicated that these two purpIe sweet potato varieties were suitabIe for processing dried sweet potato products; fried sweet potato chips of ‘Jishu No.18’ and ‘Weixiang No.1’ had moderate oiI content, high expansion degree and simiIar quality to ‘Longyan 7-3’, which indicated that these two purpIe sweet potato varieties were suitabIe for processing fried sweet potato chips; ‘Fushu No.9’, ‘Quanzi No.1’ and ‘Ninzi No.1’ exhibited beautifuI shape, high nutritional quality and good eating quality, which were suitabIe for fresh eating or processing sweet potato powder. [Conclusion] This study provided a scientific ba-sis for Iarge-scale popuIarization and appIication of new purpIe sweet potato vari-eties special y used for processing.

Investigation on the Appropriate Dose of ^(60)Co-γ Irradiation for Tubers of Purple Sweet Potato

[Objective] This study aimed to investigate the appropriate dose of 60^Co-γ irradiation for tubers of purple sweet potato.[Methods] The tubers of two purple sweet potato varieties Xuzi L-7 and Yuenanzi were used as experimental materials,and treated with 60^Co-γ irradiation at different doses（0,25,50,75,100,125 and 150 Gy） to determine the emergence rate,number of emerged seedlings per tuber and fresh weight per seedling.[Results] After the 60^Co-γ irradiation at different doses,the emergence period of tubers was postponed while the emergence rate,number of emerged seedlings per tuber and fresh weight per plant were decreased,and the differences between different varieties and different irradiation doses reached significance level.Compared with the control,the emergence period of tubers at irradiation doses above 25 Gy were postponed by 2,3,5,6 and 12 d,respectively.[Conclusion] The half lethal dose（LD50） of Xuzi L-7 was 66.73 Gy,and that of Yuenanzi was 74.96 Gy.

Analysis of Caffeoylquinic Acids in Sweetpotato by HPLC

[Objective] An HPLC method for the determination of caffeoylquinic acid compounds in sweet potato was developed in the present research. Quantitative analysis was performed on 11 sweet potato genotypes to provide a reference for the development and utilization of sweet potato, especial y on the aboveground part. [Method] Caffeoylquinic acid compounds were extracted from sweet potato leaves by ultrasonic treatment for 20 min with 200 volumes of methanol. The mobile phase of HPLC was acetonitrile -0.2% aqueous phosphoric acid. Chlorogenic acid, 4, 5-O-coffeocylquinic acid, 3, 5-O-coffeeacylquinic acid and 3, 4-O-coffeeacylquinic acid were separated wel by gradient elution, with recovery rate of 94.74%, 102.63%, 100.01% and 101.05%, respectively. [Result] The contents of caffeoylquinic acids were significantly different between sweet potato genotypes and tissue parts. Among these compounds, the content of bi-caffeoylquinic acids was the highest in the aboveground part, and the content of chlorogenic acid was the highest in the root tubers. The content of caffeoylquinic acid in different parts of the plant was： 9.77-40.86 mg/g in stem apex, 2.68-13.97 mg/g in mature leaves, 0.56-7.90 mg/g in stems and 0.69-4.33 mg/g in root tubers, respectively. [Conclusion] Sweet potato stems and leaves can be used for the extraction of chlorogenic acid in development and utilization, in which the purple sweet potato series is superior to the non-purple sweet potato series. The performance of the two purple sweet potato materials of 11ZY series is particularly prominent.

Plant Regeneration of Sweet Potato via Somatic Embryogenesis from Different Explants

[Objective] This study aimed to regenerate plants of sweet potato (Ipomoea batatas) cultivar Xushu22 via somatic embryogenesis, using leaf and shoot apex as explants. [Method] The leaf and shoot apex of Xushu 22 were separately cultured on MSB medium and MSD medium. The induced embryogenic calluses were then cultured on MS medium. The regeneration frequency of leaf and shoot apex explants were respectively calculated. [Result] The average frequency of leaf explants developing somatic callus was 95.69% compared to 30.56% in case of shoot apex explants. There were different types of morphogenic structures in the process of somatic embryo development. Leaf explants gave a high regeneration frequency to 60.61%, while the regeneration frequency of shoot apices was 22%. In addition, no morphological variations were observed in the regeneration plants. [Conclusion] Leaf explant was better than shoot apices in plant regeneration of Xushu22 via somatic embryogenesis.

β-Amylase Is Predominantly Localized to Plastids in the Developing Tuberous Root of Sweet Potato

Starch degradation in cells is closely associated with cereal seed germination, photosynthesis in leaves, carbohydrate storage in tuber and tuberous roots, and fleshy fruit development. Based on previously reported in vitro assays, β amylase is considered as one of the key enzymes catalyzing starch breakdown, but up to date its role in starch breakdown in living cells remains unclear because the enzyme was shown often extrachloroplastic in living cells. Recently we have shown for the first time that β_amylase is predominantly immuno_localized to plastids in living cells of developing apple fruit. But it remains to know whether this model of β_amylase compartmentation is more widespread in plant living cells. The present experiment, conducted in tuberous root of sweet potato ( Ipomea batatas Lam. cv. Xushu 18) and via immunogold electron_microscopy technique, showed that β amylase visualized by gold particles was predominantly localized in plastids especially at periphery of starch granules, but the gold particles were scarcely found in other subcellular compartments, indicating that the enzyme is subcellularly compartmented in the same zone as its starch substrates. The density of gold particles (β amylase) in plastids was increasing during growing season, but the predominantly plastid_distributed pattern of β amylase in cells was shown unchanged throughout the tuberous root development. These data prove that the enzyme is compartmented in its functional sites, and so provide evidence to support the possible widespread biological function of the enzyme in catalyzing starch breakdown in plant living cells or at least in living cells of plant storage organs.

Cloning and Analysis of 5’ Flanking Region of Sporamin A Gene from Sweet Potato

[ Objective] The aim of the study is to clone the 5＇ flanking region of Sporamin A gene from sweet potato. [ Method ] The sweet potato ＂Xushu 18＂ was used to amplify the 5＇ flanking region of Sporamin A gene using specifically designed primers and then target fragment was analyzed by PLACE and PlantCare online. [ Result ] Besides the conserved elements including TATA-box and CAAT-box, the cis-acting elements including sucrose responsive element CMSRE1, SP8 acting site and some other regulatory sequence such as MYB binding site were also found in Spo A promoter sequence. The results suggest that the promoter has sucrose responsive function. [ Conclusion ] The study provided reference to reveal the regulation law of Spo A, and to develop high-level expression vectors promoted by Spo A promoter.