Sweet Potato Stem Research Articles

Discovery of novel nematicidal active ingredient 2,4,7-trichloroquinazoline as a potential succinic dehydrogenase inhibitor

Plant-parasitic nematodes seriously affect the growth and yield of crops, causing huge economic losses to world agriculture. One of the effective ways to manage nematode diseases is the use of nematicides. Compound B1 was found to have good nematicidal activity in the biological test. Therefore, some compounds with similar structures to B1 were tested for better nematicidal activities. Among them, the LC50 of compound C3 against pine wood nematode (Bursaphelenchus xylophilus), rice stem nematode (Aphelenchoides besseyi), and sweet potato stem nematode (Ditylenchus destructor) were 4.6, 22.4, and 16.9 mg/L, respectively, which are markedly better than tioxazafen (103.9, 56.2, and 61.0 mg/L). Compound C3 was capable of not only significantly promoting oxidative stress in Bursaphelenchus xylophilus (B. xylophilus), but also curtailing population growth by influencing the frequency of head swing frequency, feeding behaviors, reproductive capabilities, and egg hatching rates. Furthermore, Compound C3 has demonstrated a favorable binding affinity to the succinic dehydrogenase (SDH) protein and has significantly dampened the activity of the SDH in B. xylophilus. Therefore, compound C3 can be used as a potential lead compound to discover new nematicides.

Virus-Free Sweet Potato Industry: Development Status and Production Suggestions

Sweet potato (Ipomoea batatas L.) is an important food, feed, and industrial raw material and new energy crop. Its rich nutritional value and health effects are increasingly being recognized by consumers, and the demand is increasing. However, due to the continuous cultivation of sweet potato over many years, the degeneration of seedlings and the accumulation of viral diseases are important factors affecting the yield and quality of sweet potatoes. This article provides an overview and analysis of the types and hazards of sweet potato virus diseases, the advantages of virus-free sweet potatoes, the scale of virus-free sweet potato cultivation, sweet potato stem tip virus-free production technology, its development status, and the existing problems. Combined with the development of the sweet potato industry across China, relevant development suggestions are proposed to provide a reference for promoting the healthy, stable, sustainable, high-quality, and efficient development of the sweet potato industry.

High-throughput near-infrared spectroscopy analysis of nutritional composition in sweet potato stem tips

Leaf-vegetable sweet potato is a nutritious food source, with stem tips as the harvest organ. However, the lack of rapid quantitative approaches for quality evaluation of stem tips largely limits the genetic improvement of leaf-vegetable sweet potato. This study aimed to establish a near-infrared spectroscopy (NIRS) methodology for the rapid analysis of both proximate (cellulose, crude protein, and soluble sugar) and functional (chlorogenic acid, total flavonoid content, and total phenolic content) components in the stem tips. Leveraging a dataset of 140 representative germplasm samples, we developed six robust NIRS models through the optimization of calibration sets and variable selection. These models exhibited exceptional accuracy, with high determination coefficients on calibration (R2C = 0.95–0.98), cross-validation (R2CV = 0.93–0.96), external validation (R2V = 0.91–0.95), and the ratio of prediction to deviation (RPD = 6.78–9.72). Overall, the NIRS models developed through this research facilitate high-throughput profiling of nutritional composition in stem tips, thereby enabling the swift identification of superior germplasm suited for leaf-vegetable sweet potato production.

Relationship between sensory attributes and instrumental texture properties in meat analog patty system substituted with sweet potato stem.

Understanding the relationship between perceived sensory attributes and measurable instrumental properties is crucial for replicating the distinct textures of meat in plant-based meat analogs. In this study, plant-based patties composed of textured vegetable protein (TVP) and 10%, 20% and 30% TVPs were substituted with fibers from sweet potato stem (SPS), and their instrumental texture and sensory properties were evaluated. Samples with 20% SPS showed hardness, cohesiveness and chewiness, which are the mechanical indicators most similar to those of meat. A descriptive sensory analysis by ten trained participants indicated that the SPS-supplemented meat analog patties exhibited characteristics similar to pork patties in terms of firmness, toughness, cohesiveness and smoothness compared to the TVP-only sample. A strong positive correlation between instrumental hardness and sensory firmness was observed (P < 0.01); however, cohesiveness, springiness and chewiness did not show any correlation between instrumental and sensory analyses. Warner-Bratzler shear force (WBSF) values showed positive correlations with sensory cohesiveness, chewiness, toughness, fibrousness, moistness, firmness and springiness (P < 0.05). The results demonstrated the feasibility of physically treated fibers from SPS as a partial substitute for TVP in developing meat analogs. Additionally, this study suggested that instrumental hardness and WBSF measurements can be sound parameters for representing sensory texture characteristics while further developing plant-based meat analogs. © 2024 Society of Chemical Industry.

Effects of pesticide treatment against nematode disease on soil bacterial community structure and sweet potato yield and quality

AbstractSweet potato stem nematode disease is a devastating disease, which seriously affects the yield and quality of sweet potato (Ipomoea batatas (L.) Lam.). At present, soil treatment with pesticides is mainly used to prevent sweet potato stem nematode disease. In this study, Illumina MiSeq high‐throughput sequencing technology was used to analyze the diversity of soil bacterial and fungal communities treated with different pesticides. At the same time, high performance liquid chromatography was used to determine the pesticide residues in soil and sweet potato, and the impact on sweet potato yield was investigated. Kruskal–Wallis test was used to analyze the four α‐diversity indexes of soil under different pesticide treatments, and the differences were not significant (p &gt; 0.05), indicating that there was no significant difference in the diversity and abundance of bacterial and fungal communities in soil under different pesticide treatments. The results of principal coordinate analysis showed that there was no significant difference in bacterial and fungal community structure among different pesticide treatments (p &gt; 0.05). Pesticide residue analysis and yield statistics of sweet potato showed that the residual amount of three kinds of pesticides in sweet potato did not exceed the maximum limit stipulated by the current National Standards for Food safety (GB2763‐2021). When 5% chlorpyrifos phoxim particles were applied at 15.18 kg/acre, sweet potato was unaffected by pests and diseases basically, and the yield was the highest.

Design, Synthesis, Nematicidal Activity, and Mechanism of Novel Amide Derivatives Containing an 1,2,4-Oxadiazole Moiety.

To discover new nematicides, a series of novel amide derivatives containing 1,2,4-oxadiazole were designed and synthesized. Several compounds showed excellent nematicidal activity. The LC50 values of compounds A7, A18, and A20-A22 against pine wood nematode (Bursaphelenchus xylophilus), rice stem nematode (Aphelenchoides besseyi), and sweet potato stem nematode (Ditylenchus destructor) were 1.39-3.09 mg/L, which were significantly better than the control nematicide tioxazafen (106, 49.0, and 75.0 mg/L, respectively). Compound A7 had an outstanding inhibitory effect on nematode feeding, reproductive ability, and egg hatching. Compound A7 effectively promoted the oxidative stress of nematodes and caused intestinal damage to nematodes. Compound A7 significantly inhibited the activity of succinate dehydrogenase (SDH) in nematodes, leading to blockage of electron transfer in the respiratory chain and thereby hindering the synthesis of adenosine triphosphate (ATP), which consequently affects the entire oxidative phosphorylation process to finally cause nematode death. Therefore, compound A7 can be used as a potential SDH inhibitor in nematicide applications.

RNA-Sequencing Analysis Revealed Genes Associated with Sweet Potato (Ipomoea batatas (L.) Lam.) Responses to Stem Rot during Different Infection Stages.

The sweet potato, which is an important tuber crop in China, is susceptible to a variety of pathogens and insect pests during cultivation and production. Stem rot is a common sweet potato disease that seriously affects tuber yield and quality. Unfortunately, there have been relatively few studies on the mechanism mediating the stem rot resistance of sweet potatoes. In this study, a transcriptome sequencing analysis was completed using Xushu 48 samples at different stages (T1, T2, and T3) of the stem rot infection. The T1 vs. T2, T1 vs. T3, and T2 vs. T3 comparisons detected 44,839, 81,436, and 61,932 differentially expressed genes (DEGs), respectively. The DEGs encoded proteins primarily involved in alanine, aspartate, and glutamate metabolism (ko00250), carbon fixation in photosynthetic organisms (ko00710), and amino sugar and nucleotide sugar metabolism (ko00520). Furthermore, some candidate genes induced by phytopathogen infections were identified, including gene-encoding receptor-like protein kinases (RLK5 and RLK7), an LRR receptor-like serine/threonine protein kinase (SERK1), and transcription factors (bHLH137, ERF9, MYB73, and NAC053). The results of this study provide genetic insights that are relevant to future explorations of sweet potato stem rot resistance, while also providing the theoretical basis for breeding sweet potato varieties that are resistant to stem rot and other diseases.

Experiment of stem cutting planting position in increasing sweet potato (Ipomea batatas L.) production in horticulture learning

This study aimed to discuss: (1) the effect of different positions of stem cuttings on sweet potato production; and (2) whether this practical experiment-based approach is effectively implemented in horticulture learning. This experimental research used a completely randomized design. The population was sweet potato plants. The research sample was the tip cuttings of sweet potato plants. The length of the cuttings was 30 cm, measured from the tip of the plant’s stem with relatively the same number of segments. The number of treatments was 3: upright Po (180°), inclined P1 (45°) and flat P2. The number of repetitions was six times, and the number of samples for each treatment was 20 cuttings of the sweet potato stem tips. Thus, the number of sweet potato stem tip cuttings needed in this study is 3 X 6 X 20 cuttings = 360 (three hundred and sixty). Based on the ANOVA test, a significant value of 0,005 was obtained, far smaller than the determined significance level of 0,05. It means there is a significant difference between the weights of sweet potato tubers between treatments. In conclusion, there is a significant difference between the upright/90° and slanted/45° treatment and between the upright/90° and horizontal treatment. Meanwhile, the treatment between slanted/45° and horizontal showed no significant difference. Overall, the best sweet potato production is obtained by planting horizontally with an average tuber weight of 313 grams. It can be concluded that this practical experimental method is very effectively implemented in the horticulture learning process.

Genome-wide comparative analysis of the valine glutamine motif containing genes in four Ipomoea species

BackgroundGenes with valine glutamine (VQ) motifs play an essential role in plant growth, development, and resistance to biotic and abiotic stresses. However, little information on the VQ genes in sweetpotato and other Ipomoea species is available.ResultsThis study identified 55, 58, 50 and 47 VQ genes from sweetpotato (I. batatas), I.triflida, I. triloba and I. nil, respectively. The phylogenetic analysis revealed that the VQ genes formed eight clades (I–VII), and the members in the same group exhibited similar exon–intron structure and conserved motifs distribution. The distribution of the VQ genes among the chromosomes of Ipomoea species was disproportional, with no VQ genes mapped on a few of each species' chromosomes. Duplication analysis suggested that segmental duplication significantly contributes to their expansion in sweetpotato, I.trifida, and I.triloba, while the segmental and tandem duplication contributions were comparable in I.nil. Cis-regulatory elements involved in stress responses, such as W-box, TGACG-motif, CGTCA-motif, ABRE, ARE, MBS, TCA-elements, LTR, and WUN-motif, were detected in the promoter regions of the VQ genes. A total of 30 orthologous groups were detected by syntenic analysis of the VQ genes. Based on the analysis of RNA-seq datasets, it was found that the VQ genes are expressed distinctly among different tissues and hormone or stress treatments. A total of 40 sweetpotato differentially expressed genes (DEGs) refer to biotic (sweetpotato stem nematodes and Ceratocystis fimbriata pathogen infection) or abiotic (cold, salt and drought) stress treatments were detected. Moreover, IbVQ8, IbVQ25 and IbVQ44 responded to the five stress treatments and were selected for quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis, and the results were consistent with the transcriptome analysis.ConclusionsOur study may provide new insights into the evolution of VQ genes in the four Ipomoea genomes and contribute to the future molecular breeding of sweetpotatoes.

Se-O Bond Is Unique to High Se Enriched Sweet Potato Stem Protein with Better Antioxidant Ability.

Sweet potato plants were treated with selenium (Se). Spraying Se on the sweet potato leaves was an effective Se enrichment method and proteins were extracted from the sweet potato stem. The structural characteristics of the protein were investigated. Fourier transform infrared spectroscopy (FT-IR) detected more signals from the Se-enriched sweet potato stem protein (SSP), and the number of forms of Se chemical bonds gradually increased with increasing Se content, such as the Se-O bond in high Se-enriched SSP, indicating altered secondary structures.Scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) indicated more Se atoms in the Se-enriched SSPs (SSSPs). The DSC results revealed that Se enrichment enhanced the thermal stability of the samples. Moreover, selenomethionine (SeMet), selenocystine (SeCys2), and methylselenocysteine (MeSeCys) were determined to be the main Se forms in the SSSPs. Furthermore, the SSSPs showed relatively higher superoxide anion radical and DPPH radical scavenging activities than the blank, which indicates that SSSPs can be used as antioxidants. By recovering the proteins, the agricultural by-product—sweet potato stem can be further utilized, and the obtained Se-enriched proteins may contribute to human health.

High-Quality Genome Resource of Diaporthe destruens Causing Foot Rot Disease of Sweet Potato.

Foot rot of sweet potato caused by Diaporthe destruens severely affects yield and quality worldwide. Research on this pathogen is limited due to nonavailability of genome resources. Here, we report a high-quality genome sequence of D. destruens isolate CRI 305-2, which was originally isolated from infected stem of sweet potato in Taizhou City, Zhejiang Province, China. The genome comprised a total length of 56,108,228 bp, consisted of 47 scaffolds with an overall G+C content of 48.7% and an N50 of 2,479,481 bp. This resource can be used as a reference for evolution mechanisms and comparative genomic research.

Identification and pathogenicity of Botryosphaeriaceae species associated with root and stem rot of sweet potato in Brazil

AbstractThe sweet potato (Ipomoea batatas) is characterized by the production of tuberous roots rich in starch and is one of the most produced and consumed vegetables in Brazil. Botryosphaeriaceae, among other fungi, are known to cause root and stem rot of sweet potato. However, no representative and accurate study has been performed for the correct identification of these fungal species in sweet potato in Brazil. Therefore, this study aimed to identify the Botryosphaeriaceae species associated with root and stem rot of sweet potato and confirm their pathogenicity. Tuberous roots and stems of sweet potato with rot symptoms were collected in production fields and markets and used for fungal isolations. The identification of fungi was based on the morphology of reproductive structures and phylogenetic analyses of the gene regions ITS, tef1‐α, and rpb2. The following species were identified: Lasiodiplodia theobromae, L. hormozganensis, Macrophomina phaseolina, M. euphorbiicola, M. pseudophaseolina, and Neoscytalidium dimidiatum. For the pathogenicity test, one representative isolate for each species was inoculated in healthy tuberous roots and in 30‐day‐old healthy seedlings. Black and necrotic lesions on tuberous roots and stems were observed in all replications and resulted in the death of some seedlings. This is the first report of L. hormozganensis, M. pseudophaseolina, and M. euphorbiicola, as causal agents of the stem and root rot of sweet potato and N. dimidiatum as a causal agent of stem rot worldwide.

Effects of exogenous phytohormones on chlorogenic acid accumulation and pathway-associated gene expressions in sweetpotato stem tips

Sweetpotato (Ipomoea batatas [L.] Lam.) stem tips, which contain high concentrations of chlorogenic acid (CGA), are useful as a physiologically functional food to protect against some serious diseases. According to previous studies, exogenous application of phytohormones may be an effective agrotechnical measure to control CGA biosynthesis through the transcriptional regulation of pathway gene expressions. To understand the mechanism of CGA biosynthesis in sweetpotato, we investigated the effects of exogenous phytohormones on CGA metabolism in stem tips of sweetpotato. A significantly elevated CGA content was observed in salicylic acid (SA)-treated sweetpotato stem tips at 72 h, as well as in those subjected to abscisic acid (ABA) or gibberellic acid (GA) treatments. Dynamic expression change of seven enzyme genes involved in sweetpotato CGA biosynthesis were analyzed to determine correlations between transcript levels and CGA accumulation. As revealed by the differential expression of these genes under distinct phytohormone treatments, the regulation of specific pathway genes is a critical determinant of the accumulation of CGA in sweetpotato stem tips. We also found that several hormone-responsive sites, such as those for ABA, GA, SA, and jasmonic acid (JA), were present in the promoter regions of sweetpotato CGA biosynthestic pathway genes. Collectively, phytohormones can regulate the transcription of CGA synthesis-related genes and ultimately affect CGA accumulation in sweetpotato stem tips, whereas the regulatory differences are mirrored by cis-acting elements in the corresponding pathway gene promoters.

Three Highly Sensitive and High-Throughput Serological Approaches for Detecting Dickeya dadantii in Sweet Potato.

Sweet potato stem and root rot is an important bacterial disease and often causes serious economic losses to sweet potato. Development of rapid and sensitive detection methods is crucial for diagnosis and management of this disease in field. Here, we report the production of four hybridoma cell lines (25C4, 16C10, 9B1, and 9H10) using Dickeya dadantii strain FY1710 as an immunogen. Monoclonal antibodies (MAbs) produced by these four hybridoma cell lines were highly specific and sensitive for D. dadantii detection. Indirect enzyme-linked immunosorbent assay (indirect-ELISA) results showed that the four MAbs 25C4, 16C10, 9B1, and 9H10 could detect D. dadantii in suspensions diluted to 4.89 × 104, 4.89 × 104, 9.78 × 104, and 9.78 × 104 CFU/ml, respectively. Furthermore, all four MAbs can react strongly and specifically with all four D. dadantii strains used in this study, not with the other seven tested bacterial strains. Using these four MAbs, three different serological approaches, triple-antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA), dot-ELISA, and tissue-print-ELISA, were developed for detection of D. dadantii in crude extracts prepared from field-collected sweet potato plants. Among these three methods, TAS-ELISA and dot-ELISA were used to detect D. dadantii in suspensions diluted up to 1.23 × 104 and 1.17 × 106 CFU/ml, respectively, or in sweet potato crude extracts diluted up to 1:3,840 and 1:1,920 (wt/vol, grams per milliliter), respectively. Surprisingly, both TAS-ELISA and dot-ELISA serological approaches were more sensitive than the conventional PCR. Analyses using field-collected sweet potato samples showed that the newly developed TAS-ELISA, dot-ELISA, or tissue-print-ELISA were reliable in detecting D. dadantii in sweet potato tissues. Thus, the three serological approaches were highly valuable for diagnosis of stem and root rot in sweet potato production.

Yellow nutsedge (Cyperus esculentus) interference in simulated sweetpotato plant beds

AbstractGreenhouse experiments were conducted in 2016 at Pontotoc and Verona, MS. On March 3 (Pontotoc) and March 7 (Verona), landscape fabric was placed in the bottom of polyethylene lugs, each 0.22 m2, then approximately 5 cm of a 1:1 (v/v) blend of soilless potting media and masonry sand was added. ‘Beauregard’ sweetpotato [Ipomoea batatas(L). Lam.] storage roots weighing between 85 and 227 g, and several with emerging sprouts ≤1 cm, were placed longitudinally in a single layer on the substrate, then covered with an additional 3 cm of the substrate. Sprouted yellow nutsedge (Cyperus esculentusL.) tubers were transplanted equidistantly into sweetpotato-containing lugs at six densities: 0, 18, 36, 73, 109, and 145 m−2. Trials were terminated 55 and 60 d after planting at Pontotoc and Verona, respectively. Predicted total sweetpotato stem cuttings (slips) decreased linearly from 399 to 312 m−2asC. esculentusdensity increased from 0 to 145 m−2. Predicted total slip dry weight at aC. esculentusdensity of 145 m−2was reduced 21% compared with 0 m−2. Predicted rotten sweetpotato storage roots increased from 2.6 to 11.3 m−2asC. esculentusdensity increased from 0 to 145 m−2. In response to increasingC. esculentusdensity, sweetpotato seed roots exhibited increased proximal-end dominance.

Lemon-Fruit-Based Green Synthesis of Zinc Oxide Nanoparticles and Titanium Dioxide Nanoparticles against Soft Rot Bacterial Pathogen Dickeya dadantii.

Edible plant fruits are safe raw materials free of toxicants and rich in biomolecules for reducing metal ions and stabilizing nanoparticles. Zinc oxide nanoparticles (ZnONPs) and titanium dioxide nanoparticles (TiO2NPs) are the most produced consumer nanomaterials and have known antibacterial activities but have rarely been used against phytopathogenic bacteria. Here, we synthesized ZnONPs and TiO2NPs simply by mixing ZnO or TiO2 solution with a lemon fruit extract at room temperature and showed their antibacterial activities against Dickeya dadantii, which causes sweet potato stem and root rot disease occurring in major sweet potato planting areas in China. Ultraviolet–visible spectrometry and energy dispersive spectroscopy determined their physiochemical characteristics. Transmission electron microscopy, scanning electron microscopy, and X-ray diffraction spectroscopy revealed the nanoscale size and polymorphic crystalline structures of the ZnONPs and TiO2NPs. Fourier-transform infrared spectroscopy revealed their surface stabilization groups from the lemon fruit extract. In contrast to ZnO and TiO2, which had no antibacterial activity against D. dadantii, ZnONPs and TiO2NPs showed inhibitions on D. dadantii growth, swimming motility, biofilm formation, and maceration of sweet potato tuber slices. ZnONPs and TiO2NPs showed similar extents of antibacterial activities, which increased with the increase of nanoparticle concentrations, and inhibited about 60% of D. dadantii activities at the concentration of 50 µg∙mL−1. The green synthetic ZnONPs and TiO2NPs can be used to control the sweet potato soft rot disease by control of pathogen contamination of seed tubers.

Effects of different levels of sweet potato in feeds on body composition and digestive enzymes activities of Apostichopus japonicas Selenka

The aim of this study was to test the effects of including sweet potato tuber and stem powder in feed on the body composition and digestive enzyme activities of the sea cucumber Apostichopus japonicas Selenka. Different proportions of sweet potato tuber and stem powders (from 10% to 50%) were added into compound feeds, which were supplied to A. japonicas during a 60-day experiment. The results showed that the two sweet potato ingredients had different effects on the nutrient contents of the sea cucumber body wall. The group supplied with feed containing 20% sweet potato tuber powder (T2) had the highest level of crude protein in body walls ( P 0.05). In all the groups fed with powdered sweet potato tubers (T groups), the proportions of glutamic acid and lysine in body walls were higher than those in the control, whereas the proportion of methionine decreased slightly. Different proportions of sweet potato ingredients in compound feeds also affected digestive enzyme activities in the sea cucumbers. The activities of protease and lipase first increased and then gradually decreased with increasing proportions of sweet potato materials in the feed. The highest protease activity was in the T2 and the group and the highest lipase activity was in the 10% sweet potato stem (S1) group. These results show that feed components can stimulate digestive enzyme activities in sea cucumber, and that the proportions of tubers and stems of sweet potato in feed can be adjusted to improve the digestion and growth of A. japonicas in marine farms.

고구마 줄기·잎 추출액을 이용한 견직물의 염색성

The purpose of this study was to investigate the dyeability of silk fabrics with sweet potato stem leaf extract. To obtain the optimal dyeing conditions it was examined at various dyeing conditions(temperature, pH, time and bath ratio). The dyeability and the depths of shade which were evaluated in terms of K/S and CIELAB color difference values of the dyed and mordanted fabrics were also investigated. After dyeing, various color fastness(wash fastness, dry cleaning fastness, light fastness, rub fastness, and perspiration fastness) was measured and reviewed for UV protective, deodorant and antimicrobial functionality. The optimun output, as a result, was shown at 100% of dye concentration, <TEX>$90^{\circ}C$</TEX> of dyeing temperature and 80 minutes of dyeing time while in terms of dye uptake depending on the kind of mordants and mordanting, it was found that among four mordants of <TEX>$Alk(SO_4)_2$</TEX>, <TEX>$CuSO_4$</TEX>, <TEX>$SnCl_2$</TEX>, and <TEX>$FeSO_4$</TEX>, post-mordanting with <TEX>$SnCl_2$</TEX> showed the best results. Color fastness to dry cleaning, washing and rubbing was found strong at grade 4-5 and the grade to perspiration was as good as 3 while to light fastness was good at 4 as well. In aspects of functional properties, it showed excellent results of 98.3% UV protection rate and 88% deodorization rate. Antibacterial activity was 99.9% against staphylococcus aureus and 73.3% against klebisella pneumoniae. In conclusion, we validated that the dyestuffs from the disused sweet potato stem leaf extract would be useful as a natural dye material using the optimized conditions and dyeability for silk dyeing.

Orange protein has a role in phytoene synthase stabilization in sweetpotato.

Carotenoids have essential roles in light-harvesting processes and protecting the photosynthetic machinery from photo-oxidative damage. Phytoene synthase (PSY) and Orange (Or) are key plant proteins for carotenoid biosynthesis and accumulation. We previously isolated the sweetpotato (Ipomoea batatas) Or gene (IbOr), which is involved in carotenoid accumulation and salt stress tolerance. The molecular mechanism underlying IbOr regulation of carotenoid accumulation was unknown. Here, we show that IbOr has an essential role in regulating IbPSY stability via its holdase chaperone activity both in vitro and in vivo. This protection results in carotenoid accumulation and abiotic stress tolerance. IbOr transcript levels increase in sweetpotato stem, root, and calli after exposure to heat stress. IbOr is localized in the nucleus and chloroplasts, but interacts with IbPSY only in chloroplasts. After exposure to heat stress, IbOr predominantly localizes in chloroplasts. IbOr overexpression in transgenic sweetpotato and Arabidopsis conferred enhanced tolerance to heat and oxidative stress. These results indicate that IbOr holdase chaperone activity protects IbPSY stability, which leads to carotenoid accumulation, and confers enhanced heat and oxidative stress tolerance in plants. This study provides evidence that IbOr functions as a molecular chaperone, and suggests a novel mechanism regulating carotenoid accumulation and stress tolerance in plants.

Effect of Packaging, Freezing, and Thawing Methods on the Quality Properties of Sweet Potato Stem

Effect of Packaging, Freezing, and Thawing Methods on the Quality Properties of Sweet Potato Stem