Transcriptome Analysis of Sesame (Sesamum indicum L.) Reveals the LncRNA and mRNA Regulatory Network Responding to Low Nitrogen Stress

Nitrogen is one of the important factors restricting the development of sesame planting and industry in China. Cultivating sesame varieties tolerant to low nitrogen is an effective way to solve the problem of crop nitrogen deficiency. To date, the mechanism of low nitrogen tolerance in sesame has not been elucidated at the transcriptional level. In this study, two sesame varieties Zhengzhi HL05 (ZZ, nitrogen efficient) and Burmese prolific (MD, nitrogen inefficient) in low nitrogen were used for RNA-sequencing. A total of 3964 DEGs (differentially expressed genes) and 221 DELs (differentially expressed lncRNAs) were identified in two sesame varieties at 3d and 9d after low nitrogen stress. Among them, 1227 genes related to low nitrogen tolerance are mainly located in amino acid metabolism, starch and sucrose metabolism and secondary metabolism, and participate in the process of transporter activity and antioxidant activity. In addition, a total of 209 pairs of lncRNA-mRNA were detected, including 21 pairs of trans and 188 cis. WGCNA (weighted gene co-expression network analysis) analysis divided the obtained genes into 29 modules; phenotypic association analysis identified three low-nitrogen response modules; through lncRNA-mRNA co-expression network, a number of hub genes and cis/trans-regulatory factors were identified in response to low-nitrogen stress including GS1-2 (glutamine synthetase 1-2), PAL (phenylalanine ammonia-lyase), CHS (chalcone synthase, CHS), CAB21 (chlorophyll a-b binding protein 21) and transcription factors MYB54, MYB88 and NAC75 and so on. As a trans regulator, lncRNA MSTRG.13854.1 affects the expression of some genes related to low nitrogen response by regulating the expression of MYB54, thus responding to low nitrogen stress. Our research is the first to provide a more comprehensive understanding of DEGs involved in the low nitrogen stress of sesame at the transcriptome level. These results may reveal insights into the molecular mechanisms of low nitrogen tolerance in sesame and provide diverse genetic resources involved in low nitrogen tolerance research.

Potassium attenuates drought damage by regulating sucrose metabolism and gene expression in sesame leaf

Drought has been considered the most restrictive environmental constraint on agricultural production worldwide. Photosynthetic carbohydrate metabolism is a critical biochemical process connected with crop production and quality traits. A pot experiment was carried out under four potassium (K) rates (0, 0.75, 1.5 and 2.25 g pot-1 of K, respectively) and two water regimes to investigate the role of K in activating defense mechanisms on sucrose metabolism against drought damage in sesame. The soil moisture contents are 75 ± 5% (well-watered, WW) and 45 ± 5% (drought stress, DS) of field capacity respectively. The results showed that DS plants without K application have lower activities of ribulose-1,5-bisphosphate carboxylase (Rubisco), sucrose phosphate synthase (SPS), soluble acid invertase (SAI), and chlorophyll content and higher activity of sucrose synthase (SuSy), which resulted in declined synthesis and distribution of photosynthetic products to reproductive organs. Under drought, there was a significant positive correlation between leaf sucrose metabolizing enzymes and sucrose content. Plants subjected to drought stress increased the concentrations of soluble sugar and sucrose to produce osmo-protectants and energy sources for plants acclimating to stress but decreased starch content. Conversely, K application enhanced the carbohydrate metabolism, biomass accumulation and partitioning, thereby contributing to higher seed oil and protein yield (28.8%-43.4% and 27.5%-40.7%) as compared to K-deficiency plants. The positive impacts of K application enhanced as increasing K rates, and it was more pronounced in drought conditions. Furthermore, K application upregulated the gene expression of SiMYB57, SiMYB155, SiMYB176 and SiMYB192 while downregulated SiMYB108 and SiMYB171 in drought conditions, which may help to alleviate drought susceptibility. Conclusively, our study illustrated that the enhanced photo-assimilation and translocation process caused by the changes in sucrose metabolism activities under K application as well as regulation of MYB gene expression contributes towards drought resistance of sesame.

Analysis of genes specific to the early maturation stage of Sesamum indicum seeds by subtraction method*,*

The mechanisms regulating the content ratio of unsaturated fatty acid in sesame oil need to be clarified in order to breed novel varieties with high contents of unsaturated fatty acids. Full-length cDNA libraries prepared from sesame seeds 1 to 3 weeks after flowering were subtracted with cDNAs from plantlets of 4 weeks after germination. A total of 1545 cDNA clones was sequenced. The functions of novel genes expressed specifically during the early maturation of sesame seeds were investigated by the transformation of Arabidopsis thaliana. Thirteen genes for a transcription factor were identified, four of which were involved in ethylene signaling. Fifty-nine genes, including those for the aquaporin-like protein and ethylene response factor, were analyzed by overexpression in A. thaliana. The overexpression of novel genes and the aquaporin-like protein gene in A. thaliana increased the content of unsaturated fatty acids. The localization of these products was investigated by the induction of the expression vectors for the GFP fusion protein into onion epidermal cells and sesame root cells with a particle gun. As a result, two cDNA clones were identified as good candidate genes to clarify the regulation in the yield and the ratio of unsaturated fatty acids in sesame seeds. Sein60414 (Accession No. LC603128), an intrinsic membrane protein, may be involved in the increase of unsaturated fatty acids, and Sein61074 (Accession No. LC709278) MAP3K δ-1 protein kinase in the regulation of the total ratio of unsaturated fatty acids in sesame seeds.

Genomic evolution and insights into agronomic trait innovations of Sesamum species

Sesame is an ancient oilseed crop with high oil content and quality. However, the evolutionary history and genetic mechanisms of its valuable agronomic traits remain unclear. Here, we report chromosome-scale genomes of cultivated sesame (Sesamum indicum L.) and six wild Sesamum species, representing all three karyotypes within this genus. Karyotyping and genome-based phylogenic analysis revealed the evolutionary route of Sesamum species from n = 13 to n = 16 and revealed that allotetraploidization occurred in the wild species Sesamum radiatum. Early divergence of the Sesamum genus (48.5-19.7 million years ago) during the Tertiary period and its ancient phylogenic position within eudicots were observed. Pan-genome analysis revealed 9164 core gene families in the 7 Sesamum species. These families are significantly enriched in various metabolic pathways, including fatty acid (FA) metabolism and FA biosynthesis. Structural variations in SiPT1 and SiDT1 within the phosphatidyl ethanolamine-binding protein gene family lead to the genomic evolution of plant-architecture and inflorescence-development phenotypes in Sesamum. A genome-wide association study (GWAS) of an interspecific population and genome comparisons revealed a long terminal repeat insertion and a sequence deletion in DIR genes of wild Sesamum angustifolium and cultivated sesame, respectively; both variations independently cause high susceptibility to Fusarium wilt disease. A GWAS of 560 sesame accessions combined with an overexpression study confirmed that the NAC1 and PPO genes play an important role in upregulating oil content of sesame. Our study provides high-quality genomic resources for cultivated and wild Sesamum species and insights that can improve molecular breeding strategies for sesame and other oilseed crops.

Integrated physiological, biochemical, and transcriptomics analyses reveal the underlying mechanisms of high nitrogen use efficiency of black sesame

Cultivating high nitrogen use efficient varieties is a sustainable solution to mitigating adverse effects on the environment caused by excessive nitrogen fertilizer application. However, in sesame, although immoderate nitrogen fertilizers are used to promote yield, the molecular basis of high nitrogen use efficiency (NUE) is largely unknown. Hence, this study aimed to identify high NUE black sesame variety and dissect the underlying physiological and molecular mechanisms. To achieve this, seventeen seedling traits of 30 black sesame varieties were evaluated under low nitrogen (LN) and high nitrogen (HN) conditions. Dry matter accumulation, root parameters, shoot nitrogen accumulation, and chlorophyll content are important factors for evaluating the NUE of sesame genotypes. The variety 17-156 was identified as the most efficient for N utilization. Comparative physiological and transcriptomics analyses revealed that 17-156 possesses a sophisticated nitrogen metabolizing machinery to uptake and assimilate higher quantities of inorganic nitrogen into amino acids and proteins, and simultaneously improving carbon metabolism and growth. Specifically, the total nitrogen and soluble protein contents significantly increased with the increase in nitrogen concentrations. Many important genes, including nitrate transporters (NPFs), amino acid metabolism-related (GS, GOGAT, GDH, etc.), phytohormone-related, and transcription factors, were significantly up-regulated in 17-156 under HN condition. In addition, 38 potential candidate genes were identified for future studies toward improving sesame's NUE. These findings offer valuable resources for deciphering the regulatory network of nitrogen metabolism and developing sesame cultivars with improved NUE.

Genome-wide identification and expression analysis of the trihelix transcription factor family in sesame (Sesamum indicum L.) under abiotic stress

BACKGROUND

The plant trihelix gene family is among the earliest discovered transcription factor families, and it is vital in modulating light, plant growth, and stress responses.

METHODS

The identification and characterization of trihelix family members in the sesame genome were analyzed by bioinformatics methods, and the expression patterns of sesame trihelix genes were assessed by quantitative real-time PCR.

RESULTS

There were 34 trihelix genes discovered in the genome of sesame, which were irregularly distributed among 10 linkage groups. Also, the genome contained 5 duplicate gene pairs. The 34 trihelix genes were divided into six sub-families through a phylogenetic study. A tissue-specific expression revealed that SiTH genes exhibited spatial expression patterns distinct from other trihelix genes in the same subfamily. The cis-element showed that the SiTHs gene promoter contained various elements associated with responses to hormones and multiple abiotic stresses. Additionally, the expression patterns of 8 SiTH genes in leaves under abiotic stresses demonstrated that all selected genes were significantly upregulated or downregulated at least once in the stress period. Furthermore, the SiTH4 gene was significantly induced in response to drought and salt stress, showing that SiTH genes may be engaged in the stress response mechanisms of sesame.

CONCLUSION

These findings establish a foundation for further investigation of the trihelix gene-mediated response to abiotic stress in sesame.

Effect of sesame (Sesamum indicum L.) consumption on glycemic control in patients with type 2 diabetes: A systematic review and meta-analysis of randomized controlled trials

Conflicting evidence exists on the effect of sesame consumption on glucose metabolism in patients with type 2 diabetes (T2D). Therefore, this meta-analysis focuses on the relationship between sesame (Sesamum indicum L.) intervention and glycemic control in patients with T2D. Published literature was retrieved and screened from PubMed, Scopus, ISI Web of Science, and the Cochrane Library up to December 2022. Outcome measures included fasting blood sugar (FBS) concentrations, fasting insulin levels, and hemoglobin A1c (HbA1c) percentage. Pooled effect sizes were reported as weighted mean differences (WMDs) and 95% confidence intervals (CIs). Eight clinical trials (395 participants) were eligible for meta-analyses. Overall, sesame consumption significantly reduced serum FBS (WMD: -28.61 mg/dL, 95% CI: -36.07 to -21.16, p˂0.001; I2  = 98.3%) and HbA1c percentage (WMD: -0.99%, 95% CI: -1.22 to -0.76, p ≤ 0.001; I2  = 65.1%) in patients with T2D. However, sesame consumption did not significantly influence fasting insulin levels (Hedges's: 2.29, 95% CI: -0.06 to 4.63, p = 0.06; I2  = 98.1%). In summary, the current meta-analysis showed a promising effect of sesame consumption on glycemic control through reducing FBS and HbA1c, yet additional prospective studies are recommended, using higher doses and longer intervention period, to confirm the impact of sesame consumption on insulin levels in T2D patients.

Omics technologies towards sesame improvement: a review

Genetic improvement of sesame (Sesamum indicum L.), one of the most important oilseed crops providing edible oil, proteins, minerals, and vitamins, is important to ensure a balanced diet for the growing world population. Increasing yield, seed protein, oil, minerals, and vitamins is urgently needed to meet the global demand. The production and productivity of sesame is very low due to various biotic and abiotic stresses. Therefore, various efforts have been made to combat these constraints and increase the production and productivity of sesame through conventional breeding. However, less attention has been paid to the genetic improvement of the crop through modern biotechnological methods, leaving it lagging behind other oilseed crops. Recently, however, the scenario has changed as sesame research has entered the era of "omics" and has made significant progress. Therefore, the purpose of this paper is to provide an overview of the progress made by omics research in improving sesame. This review presents a number of efforts that have been made over past decade using omics technologies to improve various traits of sesame, including seed composition, yield, and biotic and abiotic resistant varieties. It summarizes the advances in genetic improvement of sesame using omics technologies, such as germplasm development (web-based functional databases and germplasm resources), gene discovery (molecular markers and genetic linkage map construction), proteomics, transcriptomics, and metabolomics that have been carried out in the last decade. In conclusion, this review highlights future directions that may be important for omics-assisted breeding in sesame genetic improvement.

Resequencing of 410 Sesame Accessions Identifies SINST1 as the Major Underlying Gene for Lignans Variation

Sesame is a promising oilseed crop that produces specific lignans of clinical importance. Hence, a molecular description of the regulatory mechanisms of lignan biosynthesis is essential for crop improvement. Here, we resequence 410 sesame accessions and identify 5.38 and 1.16 million SNPs (single nucleotide polymorphisms) and InDels, respectively. Population genomic analyses reveal that sesame has evolved a geographic pattern categorized into northern (NC), middle (MC), and southern (SC) groups, with potential origin in the southern region and subsequent introduction to the other regions. Selective sweeps analysis uncovers 120 and 75 significant selected genomic regions in MC and NC groups, respectively. By screening these genomic regions, we unveiled 184 common genes positively selected in these subpopulations for exploitation in sesame improvement. Genome-wide association study identifies 17 and 72 SNP loci for sesamin and sesamolin variation, respectively, and 11 candidate causative genes. The major pleiotropic SNP^C/A locus for lignans variation is located in the exon of the gene SiNST1. Further analyses revealed that this locus was positively selected in higher lignan content sesame accessions, and the "C" allele is favorable for a higher accumulation of lignans. Overexpression of SiNST1^C in sesame hairy roots significantly up-regulated the expression of SiMYB58, SiMYB209, SiMYB134, SiMYB276, and most of the monolignol biosynthetic genes. Consequently, the lignans content was significantly increased, and the lignin content was slightly increased. Our findings provide insights into lignans and lignin regulation in sesame and will facilitate molecular breeding of elite varieties and marker-traits association studies.

Therapeutic Effectiveness of Sesame Preparations and its Bioactive Ingredients in Management of Cardiometabolic Syndrome in Diabetes Mellitus: A Systematic Review

AIM

This systematic review aimed to appraise and recapitulate all research investigations to elucidate the effects of Sesamum indicum preparations on managing the cardiometabolic syndrome of Diabetes mellitus (DM) and metabolic syndrome (MetS).

METHODS

A systematic review was carried out in a Cochrane fashion and in compliance with the PRISMA checklist using the published academic works in PubMed/MEDLINE, WOS, SCOPUS, and EMBASE databases that were searched up to June 2021. Abstracts that met PICO criteria for qualitative studies were duplicate reviewed for data extraction to assess the quality and details of the study.

RESULTS

Sesamum indicum preparations and its bioactive lignans, such as sesamin, sesamol, and pinoresinol, were found to possess anti-hyperglycemic, anti-hyperlipidemia, anti-inflammatory, antioxidative, anti-hypertensive, cardioprotective, and hepatoprotective effects both in patients with T2DM as well as in experimental animal models with T1DM and MetS. The incorporation of sesame oil as a natural adjuvant can be effective in improving vascular reactivity and aortic permeability, reproductive parameters, and diabetic nephropathy, as well as modification of anthropometry indices. Therefore, sesame oil and bioactive lignans as combination therapy with drugs can exhibit synergistic effects and provide a favorable preference in clinical settings.

CONCLUSION

Sesame oil and lignans present in it act in a dose-dependent manner. The best dosage to improve risk biomarkers of patients with T2DM and MetS is 30-35 ml daily of sesame oil or inclusion of sesame oil in daily dietary patterns up to 30% of total energy for 8-12 weeks and/or 200 mg daily of sesamin supplementation for eight weeks.

Genome-wide association analysis and transcriptome reveal novel loci and a candidate regulatory gene of fatty acid biosynthesis in sesame (Sesamum indicum L.)

The regulatory mechanisms of fatty acid (FA) biosynthesis and triacylglycerols (TAGs) assembly remain largely misunderstood in sesame. Gas chromatography was used to analyze the natural variation in FA compositions and oil content (OC) in 400 sesame accessions grown in three different environments. The phenotypic data was associated with the newly released SNP data from whole-genome resequencing, and 43 significant loci for FA and OC were identified. Comparative transcriptomics analysis of high-OC and low-OC materials was performed, and 515 differentially expressed genes (DEGs) were identified across three seed developmental stages. By integrating the genome-wide association study (GWAS) and DEGs analysis, twenty candidate genes were identified, of which SiTPS1 (trehalose-6-phosphate synthase 1) has emerged as a key regulatory gene of FAs and TAGs metabolism in sesame. Overexpression of SiTPS1 in transgenic Arabidopsis influenced FA composition and significantly increased OC. Our study provides resources for the markers-based improvement of OC and quality in sesame and other crops.

Genome-wide characterization and identification of candidate ERF genes involved in various abiotic stress responses in sesame (Sesamum indicum L.)

BACKGROUND

The adverse effects of climate change on crop production are constraining breeders to develop high-quality environmentally stable varieties. Hence, efforts are being made to identify key genes that could be targeted for enhancing crop tolerance to environmental stresses. ERF transcription factors play an important role in various abiotic stresses in plants. However, the roles of the ERF family in abiotic stresses tolerance are still largely unknown in sesame, the "queen" of oilseed crops.

RESULTS

In total, 114 sesame ERF genes (SiERFs) were identified and characterized. 96.49% of the SiERFs were distributed unevenly on the 16 linkage groups of the sesame genome. The phylogenetic analysis with the Arabidopsis ERFs (AtERFs) subdivided SiERF subfamily proteins into 11 subgroups (Groups I to X; and VI-L). Genes in the same subgroup exhibited similar structure and conserved motifs. Evolutionary analysis showed that the expansion of ERF genes in sesame was mainly induced by whole-genome duplication events. Moreover, cis-acting elements analysis showed that SiERFs are mostly involved in environmental responses. Gene expression profiles analysis revealed that 59 and 26 SiERFs are highly stimulated under drought and waterlogging stress, respectively. In addition, qRT-PCR analyses indicated that most of SiERFs are also significantly up-regulated under osmotic, submerge, ABA, and ACC stresses. Among them, SiERF23 and SiERF54 were the most induced by both the abiotic stresses, suggesting their potential for targeted improvement of sesame response to multiple abiotic stresses.

CONCLUSION

This study provides a comprehensive understanding of the structure, classification, evolution, and abiotic stresses response of ERF genes in sesame. Moreover, it offers valuable gene resources for functional characterization towards enhancing sesame tolerance to multiple abiotic stresses.

Overexpression of sesame polyketide synthase A leads to abnormal pollen development in Arabidopsis

BACKGROUND

Sesame is a great reservoir of bioactive constituents and unique antioxidant components. It is widely used for its nutritional and medicinal value. The expanding demand for sesame seeds is putting pressure on sesame breeders to develop high-yielding varieties. A hybrid breeding strategy based on male sterility is one of the most effective ways to increase the crop yield. To date, little is known about the genes and mechanism underlying sesame male fertility. Therefore, studies are being conducted to identify and functionally characterize key candidate genes involved in sesame pollen development. Polyketide synthases (PKSs) are critical enzymes involved in the biosynthesis of sporopollenin, the primary component of pollen exine. Their in planta functions are being investigated for applications in crop breeding.

RESULTS

In this study, we cloned the sesame POLYKETIDE SYNTHASE A (SiPKSA) and examined its function in male sterility. SiPKSA was specifically expressed in sesame flower buds, and its expression was significantly higher in sterile sesame anthers than in fertile anthers during the tetrad and microspore development stages. Furthermore, overexpression of SiPKSA in Arabidopsis caused male sterility in transgenic plants. Ultrastructural observation showed that the pollen grains of SiPKSA-overexpressing plants contained few cytoplasmic inclusions and exhibited an abnormal pollen wall structure, with a thicker exine layer compared to the wild type. In agreement with this, the expression of a set of sporopollenin biosynthesis-related genes and the contents of their fatty acids and phenolics were significantly altered in anthers of SiPKSA-overexpressing plants compared with wild type during anther development.

CONCLUSION

These findings highlighted that overexpression of SiPKSA in Arabidopsis might cause male sterility through defective pollen wall formation. Moreover, they suggested that SiPKSA modulates vibrant pollen development via sporopollenin biosynthesis, and a defect in its regulation may induce male sterility. Therefore, genetic manipulation of SiPKSA might promote hybrid breeding in sesame and other crop species.

The effect of hydrolyzed sesame meal protein on the quality and shelf life of hamburgers during refrigerated storage

In this study, to improve the quality and shelf life of hamburgers, sesame meal protein hydrolysates (SPH) were produced using two enzymes of alcalase and flavourzyme and then four hamburger treatments: T1: control (10% soybean), T2: 1% SPH + soybean 9%, T3: 2% SPH + soybean 8%, and T4: 3% SPH + soybean 7% were prepared. Physicochemical properties were analyzed at the beginning of the storage period; microbial and chemical quality was evaluated at intervals of 0, 4, 8, 12, and 16 days. The results of SPH showed that alcalase enzyme can produce a SPH with a higher antioxidant properties (DPPH, FRAP, and beta-carotene-linoleic acid) (P < 0.05); therefore, this SPH was used for hamburger properties. According to the results, with the addition of SPH, moisture, fat, texture firmness decreased, protein, and brightness increased (P < 0.05), and all treatments had the allowable range. SPH replacement with soybean slowed down the increasing trend of oxidation and microbial spoilage (P < 0.05). In general, better results were observed in T3 and T4, which had a permissible range chemical and microbial index until the end of the storage period, as well as these treatments inhibited the growth of Staphylococcus aureus and Escherichia coli. Only T3 was approved by the evaluators.

Comparative metabolomics analysis of different sesame (Sesamum indicum L.) tissues reveals a tissue-specific accumulation of metabolites

BACKGROUND

Sesame (Sesamum indicum L.) leaves, flowers, especially seeds are used in traditional medicine to prevent or cure various diseases. Its seed's market is expanding. However, the other tissues are still underexploited due to the lack of information related to metabolites distribution and variability in the plant. Herein, the metabolite profiles of five sesame tissues (leaves, fresh seeds, white and purple flowers, and fresh carpels) have been investigated using ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS/MS)-based widely targeted metabolomics analysis platform.

RESULTS

In total, 776 metabolites belonging to diverse classes were qualitatively and quantitatively identified. The different tissues exhibited obvious differences in metabolites composition. The majority of flavonoids predominantly accumulated in flowers. Amino acids and derivatives, and lipids were identified predominantly in fresh seeds followed by flowers. Many metabolites, including quinones, coumarins, tannins, vitamins, terpenoids and some bioactive phenolic acids (acteoside, isoacteoside, verbascoside, plantamajoside, etc.) accumulated mostly in leaves. Lignans were principally detected in seeds. 238 key significantly differential metabolites were filtered out. KEGG annotation and enrichment analyses of the differential metabolites revealed that flavonoid biosynthesis, amino acids biosynthesis, and phenylpropanoid biosynthesis were the main differently regulated pathways. In addition to the tissue-specific accumulation of metabolites, we noticed a cooperative relationship between leaves, fresh carpels, and developing seeds in terms of metabolites transfer. Delphinidin-3-O-(6"-O-p-coumaroyl)glucoside and most of the flavonols were up-regulated in the purple flowers indicating they might be responsible for the purple coloration.

CONCLUSION

This study revealed that the metabolic processes in the sesame tissues are differently regulated. It offers valuable resources for investigating gene-metabolites interactions in sesame tissues and examining metabolic transports during seed development in sesame. Furthermore, our findings provide crucial knowledge that will facilitate sesame biomass valorization.

Genome-Wide Analysis of nsLTP Gene Family and Identification of SiLTPs Contributing to High Oil Accumulation in Sesame (Sesamum indicum L.)

The biosynthesis and storage of lipids in oil crop seeds involve many gene families, such as nonspecific lipid-transfer proteins (nsLTPs). nsLTPs are cysteine-rich small basic proteins essential for plant development and survival. However, in sesame, information related to nsLTPs was limited. Thus, the objectives of this study were to identify the Sesamum indicum nsLTPs (SiLTPs) and reveal their potential role in oil accumulation in sesame seeds. Genome-wide analysis revealed 52 SiLTPs, nonrandomly distributed on 10 chromosomes in the sesame variety Zhongzhi 13. Following recent classification methods, the SiLTPs were divided into nine types, among which types I and XI were the dominants. We found that the SiLTPs could interact with several transcription factors, including APETALA2 (AP2), DNA binding with one finger (Dof), etc. Transcriptome analysis showed a tissue-specific expression of some SiLTP genes. By integrating the SiLTPs expression profiles and the weighted gene co-expression network analysis (WGCNA) results of two contrasting oil content sesame varieties, we identified SiLTPI.23 and SiLTPI.28 as the candidate genes for high oil content in sesame seeds. The presumed functions of the candidate gene were validated through overexpression of SiLTPI.23 in Arabidopsis thaliana. These findings expand our knowledge on nsLTPs in sesame and provide resources for functional studies and genetic improvement of oil content in sesame seeds.

Effects of "nine steaming nine sun-drying" on proximate composition, oil properties and volatile compounds of black sesame seeds

Black sesame seeds (BSS) were processed by nine cycles of steaming and sun-drying, and the chemistry of their resulting products studied. That is, the shell color and structure, proximate composition, oil properties and volatile compounds of raw BSS were determined and compared with processed BSS. Various levels of shell color change and structure damage were observed. The proximate composition also differed, whereas the relative proportion of fatty acids and oil properties were unchanged. SPME-GCMS analysis revealed that aldehydes, hydrocarbons and alcohols were the main volatile compounds. And compared with raw BSS, four volatile substances were newly detected in the processed BSS. Principal component analysis (PCA) displayed the overall difference between samples and showed that repeated steaming and sun-drying process had a significant impact on the chemical composition of BSS.

Genetic Architecture Underpinning Yield Components and Seed Mineral-Nutrients in Sesame

Genetic dissection of yield components and seed mineral-nutrient is crucial for understanding plant physiological and biochemical processes and alleviate nutrient malnutrition. Sesame (Sesamum indicum L.) is an orphan crop that harbors rich allelic repertoire for seed mineral-nutrients. Here, we harness this wide diversity to study the genetic architecture of yield components and seed mineral-nutrients using a core-collection of worldwide genotypes and segregating mapping population. We also tested the association between these traits and the effect of seed nutrients concentration on their bio-accessibility. Wide genetic diversity for yield components and seed mineral-nutrients was found among the core-collection. A high-density linkage map consisting of 19,309 markers was constructed and used for genetic mapping of 84 QTL associated with yield components and 50 QTL for seed minerals. To the best of our knowledge, this is the first report on mineral-nutrients QTL in sesame. Genomic regions with a cluster of overlapping QTL for several morphological and nutritional traits were identified and considered as genomic hotspots. Candidate gene analysis revealed potential functional associations between QTL and corresponding genes, which offers unique opportunities for synchronous improvement of mineral-nutrients. Our findings shed-light on the genetic architecture of yield components, seed mineral-nutrients and their inter- and intra- relationships, which may facilitate future breeding efforts to develop bio-fortified sesame cultivars.

Phytoavailability-based threshold values for cadmium in soil for safer crop production

The phytoavailability of heavy metals in soils is important for both food safety and environmental management. Hence soil metal phytoavailability threshold values need to be established based on a firm scientific basis. In this study, optimal Cd phytoavailability threshold values, were determined for bean, rice and sesame cultivated in 100 soils varying widely in soil chemical characteristics by comparing the soil Cd phytoavailability obtained using three commonly used extraction procedures. Subsequently, the transfer functions derived in this study, were used to establish soil Cd phytoavailability threshold value standard limits for each specific crop. In addition, independent experimental data were used to supplement the obtained soil phytoavailable Cd threshold value for rice. Soil phytoavailable Cd concentrations extracted by 1 M NH4NO3, 0.05 M EDTA and Mehlich3 solutions were each more significantly correlated with plant Cd concentrations than total soil Cd concentrations. Thus, the soil Cd phytoavailability threshold values proposed in this study provide a more effective means of ensuring safer agricultural food production. Therefore, it is recommended that current agricultural soil heavy metal management policy; which is based on total concentrations; should be changed to embrace soil metal phytoavailability for safer agricultural food production.

Novel ACE Inhibitory Peptides Derived from Simulated Gastrointestinal Digestion in Vitro of Sesame (Sesamum indicum L.) Protein and Molecular Docking Study

The aim of this study was to isolate and identify angiotensin I-converting enzyme (ACE) inhibitory peptides from sesame protein through simulated gastrointestinal digestion in vitro, and to explore the underlying mechanisms by molecular docking. The sesame protein was enzymatically hydrolyzed by pepsin, trypsin, and α-chymotrypsin. The degree of hydrolysis (DH) and peptide yield increased with the increase of digest time. Moreover, ACE inhibitory activity was enhanced after digestion. The sesame protein digestive solution (SPDS) was purified by ultrafiltration through different molecular weight cut-off (MWCO) membranes and SPDS-VII (< 3 kDa) had the strongest ACE inhibition. SPDS-VII was further purified by NGC Quest™ 10 Plus Chromatography System and finally 11 peptides were identified by Nano UHPLC-ESI-MS/MS (nano ultra-high performance liquid chromatography-electrospray ionization mass spectrometry/mass spectrometry) from peak 4. The peptide GHIITVAR from 11S globulin displayed the strongest ACE inhibitory activity (IC50 = 3.60 ± 0.10 μM). Furthermore, the docking analysis revealed that the ACE inhibition of GHIITVAR was mainly attributed to forming very strong hydrogen bonds with the active sites of ACE. These results identify sesame protein as a rich source of ACE inhibitory peptides and further indicate that GHIITVAR has the potential for development of new functional foods.

Cytological, genetic, and proteomic analysis of a sesame (Sesamum indicum L.) mutant Siyl-1 with yellow-green leaf color

BACKGROUND

Both photosynthetic pigments and chloroplasts in plant leaf cells play an important role in deciding on the photosynthetic capacity and efficiency in plants. Systematical investigating the regulatory mechanism of chloroplast development and chlorophyll (Chl) content variation is necessary for clarifying the photosynthesis mechanism for crops.

OBJECTIVE

This study aims to explore the critical regulatory mechanism of leaf color mutation in a yellow-green leaf sesame mutant Siyl-1.

METHODS

We performed the genetic analysis of the yellow-green leaf color mutation using the F2 population of the mutant Siyl-1. We compared the morphological structure of the chloroplasts, chlorophyll content of the three genotypes of the mutant F2 progeny. We performed the two-dimensional gel electrophoresis (2-DE) and compared the protein expression variation between the mutant progeny and the wild type.

RESULTS

Genetic analysis indicated that there were 3 phenotypes of the F2 population of the mutant Siyl-1, i.e., YY type with light-yellow leaf color (lethal); Yy type with yellow-green leaf color, and yy type with normal green leaf color. The yellow-green mutation was controlled by an incompletely dominant nuclear gene, Siyl-1. Compared with the wild genotype, the chloroplast number and the morphological structure in YY and Yy mutant lines varied evidently. The chlorophyll content also significantly decreased (P < 0.05). The 2-DE comparison showed that there were 98 differentially expressed proteins (DEPs) among YY, Yy, and yy lines. All the 98 DEPs were classified into 5 functional groups. Of which 82.7% DEPs proteins belonged to the photosynthesis and energy metabolism group.

CONCLUSION

The results revealed the genetic character of yellow-green leaf color mutant Siyl-1. 98 DEPs were found in YY and Yy mutant compared with the wild genotype. The regulation pathway related with the yellow leaf trait mutation in sesame was analyzed for the first time. The findings supplied the basic theoretical and gene basis for leaf color and chloroplast development mechanism in sesame.

An integrated omics analysis reveals molecular mechanisms that are associated with differences in seed oil content between Glycine max and Brassica napus

BACKGROUND

Rapeseed (Brassica napus L.) and soybean (Glycine max L.) seeds are rich in both protein and oil, which are major sources of biofuels and nutrition. Although the difference in seed oil content between soybean (~ 20%) and rapeseed (~ 40%) exists, little is known about its underlying molecular mechanism.

RESULTS

An integrated omics analysis was performed in soybean, rapeseed, Arabidopsis (Arabidopsis thaliana L. Heynh), and sesame (Sesamum indicum L.), based on Arabidopsis acyl-lipid metabolism- and carbon metabolism-related genes. As a result, candidate genes and their transcription factors and microRNAs, along with phylogenetic analysis and co-expression network analysis of the PEPC gene family, were found to be largely associated with the difference between the two species. First, three soybean genes (Glyma.13G148600, Glyma.13G207900 and Glyma.12G122900) co-expressed with GmPEPC1 are specifically enriched during seed storage protein accumulation stages, while the expression of BnPEPC1 is putatively inhibited by bna-miR169, and two genes BnSTKA and BnCKII are co-expressed with BnPEPC1 and are specifically associated with plant circadian rhythm, which are related to seed oil biosynthesis. Then, in de novo fatty acid synthesis there are rapeseed-specific genes encoding subunits β-CT (BnaC05g37990D) and BCCP1 (BnaA03g06000D) of heterogeneous ACCase, which could interfere with synthesis rate, and β-CT is positively regulated by four transcription factors (BnaA01g37250D, BnaA02g26190D, BnaC01g01040D and BnaC07g21470D). In triglyceride synthesis, GmLPAAT2 is putatively inhibited by three miRNAs (gma-miR171, gma-miR1516 and gma-miR5775). Finally, in rapeseed there was evidence for the expansion of gene families, CALO, OBO and STERO, related to lipid storage, and the contraction of gene families, LOX, LAH and HSI2, related to oil degradation.

CONCLUSIONS

The molecular mechanisms associated with differences in seed oil content provide the basis for future breeding efforts to improve seed oil content.

The contrasting response to drought and waterlogging is underpinned by divergent DNA methylation programs associated with transcript accumulation in sesame

DNA methylation is a heritable epigenetic mechanism that participates in gene regulation under abiotic stresses in plants. Sesame (Sesamum indicum) is typically considered a drought-tolerant crop but highly susceptible to waterlogging, probably because of its origin in Africa or India. Understanding DNA methylation patterns under drought and waterlogging conditions can provide insights into the regulatory mechanisms underlying sesame contrasting responses to these abiotic stresses. We combined Methylation-Sensitive Amplified Polymorphism and transcriptome analyses to profile cytosine methylation patterns, transcript accumulation, and their interplay in drought-tolerant and waterlogging-tolerant sesame genotypes. Drought stress strongly induced de novo methylation (DNM) whereas most of the loci were demethylated (DM) during the recovery phase. In contrast, waterlogging stress decreased the level of methylation but during the recovery phase, both DM and DNM were concomitantly deployed. In both stresses, the levels of the differentially accumulated transcripts (DATs) highly correlated with the methylation patterns. We observed that DM was associated with an increase of DAT levels while DNM was correlated with a decrease of DAT levels. Altogether, sesame has divergent epigenetic programs that respond to drought and waterlogging stresses and an interplay among DNA methylation and transcript accumulation may partly modulate the contrasting responses to these stresses.

Impact of different amendments on biochemical responses of sesame (Sesamum indicum L.) plants grown in lead-cadmium contaminated soil

Soil co-contamination with lead (Pb) and cadmium (Cd) is a tenacious risk to crop production globally. The current experiment observed the roles of amendments [biochar (BC), slag (SL), and ferrous manganese ore (FMO)] for enhancing Pb and Cd tolerance in sesame (Sesamum indicum L.). Our results revealed that application of amendments significantly enhanced the nutrient level of sesame seedlings developed under extreme Pb and Cd conditions. The higher Pb and Cd-tolerance in sesame encouraged by amendments might be credited to its capability to restrict Pb and Cd uptake and decreased oxidative damage induced by Pb and Cd that is also demonstrated by lesser production of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and reduced electrolyte leakage (EL) in plant biomass. The added amendments relieved Pb and Cd toxicity and improved photosynthetic pigments, soluble protein, and proline content. Not only this amendments also decreased the antioxidant bulk, such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in sesame plants compared to control when exposed to Pb and Cd. Moreover, the added amendments = down-regulated the genes expression which regulate the SOD, POD, and CAT activity in sesame under Pb and Cd-stress. Furthermore, supplementation of amendments to the soil, reduced the bio accessibility (SBET), leachability (TCLP), and mobility (CaCl₂) of Pb and Cd. Collectively, our findings conclude that the application of amendments enhanced sesame tolerance to Pb and Cd stress by restricting Pb and Cd accumulation, maintained photosynthetic presentation and dropped oxidative loss through enhanced antioxidant system, thus signifying amendments as an operational stress regulators in modifying Pb and Cd-toxicity that is highly important economically in all crops including sesame.

Formation of a Methylenedioxy Bridge in (+)-Epipinoresinol by CYP81Q3 Corroborates with Diastereomeric Specialization in Sesame Lignans

Plant specialized metabolites are often found as lineage-specific diastereomeric isomers. For example, Sesamum alatum accumulates the specialized metabolite (+)-2-episesalatin, a furofuran-type lignan with a characteristic diastereomeric configuration rarely found in other Sesamum spp. However, little is known regarding how diastereomeric specificity in lignan biosynthesis is implemented in planta. Here, we show that S. alatum CYP81Q3, a P450 orthologous to S. indicum CYP81Q1, specifically catalyzes methylenedioxy bridge (MDB) formation in (+)-epipinoresinol to produce (+)-pluviatilol. Both (+)-epipinoresinol and (+)-pluviatilol are putative intermediates of (+)-2-episesalatin based on their diastereomeric configurations. On the other hand, CYP81Q3 accepts neither (+)- nor (-)-pinoresinol as a substrate. This diastereomeric selectivity of CYP81Q3 is in clear contrast to that of CYP81Q1, which specifically converts (+)-pinoresinol to (+)-sesamin via (+)-piperitol by the sequential formation of two MDBs but does not accept (+)-epipinoresinol as a substrate. Moreover, (+)-pinoresinol does not interfere with the conversion of (+)-epipinoresinol to (+)-pluviatilol by CYP81Q3. Amino acid substitution and CO difference spectral analyses show that polymorphic residues between CYP81Q1 and CYP81Q3 proximal to their putative substrate pockets are crucial for the functional diversity and stability of these two enzymes. Our data provide clues to understanding how the lineage-specific functional differentiation of respective biosynthetic enzymes substantiates the stereoisomeric diversity of lignan structures.

Identification and characterization of the bZIP transcription factor family and its expression in response to abiotic stresses in sesame

Basic leucine zipper (bZIP) gene family is one of the largest transcription factor families in plants, and members of this family play important roles in multiple biological processes such as light signaling, seed maturation, flower development as well as abiotic and biotic stress responses. Nonetheless, genome-wide comprehensive analysis of the bZIP family is lacking in the important oil crop sesame. In the present study, 63 bZIP genes distributed on 14 linkage groups were identified in sesame, and denominated as SibZIP01-SibZIP63. Besides, all members of SibZIP family were divided into nine groups based on the phylogenetic relationship of Arabidopsis bZIPs, which was further supported by the analysis of their conserved motifs and gene structures. Promoter analysis showed that all SibZIP genes harbor cis-elements related to stress responsiveness in their promoter regions. Expression analyses of SibZIP genes based on transcriptome data showed that these genes have different expression patterns in different tissues. Additionally, we showed that a majority of SibZIPs (85.71%) exhibited significant transcriptional changes in responses to abiotic stresses, including drought, waterlogging, osmotic, salt, and cold, suggesting that SibZIPs may play a cardinal role in the regulation of stress responses in sesame. Together, these results provide new insights into stress-responsive SibZIP genes and pave the way for future studies of SibZIPs-mediated abiotic stress response in sesame.

Identification of Nutritional Components in Black Sesame Determined by Widely Targeted Metabolomics and Traditional Chinese Medicines

Chemical composition of secondary metabolites is of great importance for quality control of agricultural products. Black sesame seeds are significantly more expensive than white sesame seeds, because it is thought that black sesame seeds are more beneficial to human health than white sesame seeds. However, the differences in nutrient composition between black sesame seeds and white sesame seeds are still unknown. The current study examined the levels of different metabolites in black and white sesame seeds via the use of a novel metabolomics strategy. Using widely targeted metabolomics data, we obtained the structure and content of 557 metabolites, out of which 217 metabolites were identified, and discovered 30 metabolic pathways activated by the secondary metabolites in both black and white sesame seeds. Our results demonstrated that the main pathways that were differentially activated included: phenylpropanoid biosynthesis, tyrosine metabolism, and riboflavin metabolism. More importantly, the biomarkers that were significantly different between black seeds and white sesame seeds are highly related to the functions recorded in traditional Chinese medicine. The results of this study may serve as a new theoretical reference for breeding experts to promote the genetic improvement of sesame seeds, and therefore the cultivation of higher quality sesame varieties.

Oxidative stability of sesame and flaxseed oils and their effects on morphometric and biochemical parameters in an animal model

BACKGROUND

Sesame and flaxseed oils, which are rich in essential n-6 and n-3 polyunsaturated fatty acids, are widely consumed. We have determined the optical behavior with respect to the quality and identity of cold-pressed sesame and flaxseed oils. The effects of these oils and their combinations on metabolic parameters in animal models were also measured.

RESULTS

Flaxseed oil emitted carotenoid fluorescence (500-650 nm), although it was more unstable than sesame oil, which had a larger induction period by the Rancimat method. The greater stability of sesame may be a result of the lower quantity of linolenic fatty acids. These oils were added to the feed of 56 rats, whereas animal fat was used for the control group. The sesame oil, flaxseed oil and sesame + flaxseed oils groups showed a significantly reduced adiposity index and blood glucose compared to the control group, whereas total cholesterol, high-density lipoprotein and triglycerides were lower in flaxseed oil and sesame + flaxseed oils (P < 0.05). Sesame + flaxseed oils had reduced levels of low-density lipoprotein and non-high-density lipoprotein (P < 0.05), indicating an anti-atherogenic effect in this group.

CONCLUSION

Sesame oil was more stable than flaxseed oil. In an animal model, the diets with polyunsaturated fat sources proportions of 1:1 n-6:n-3 polyunsaturated fatty acids, improved the metabolic parameters, implying cardioprotective effects. © 2016 Society of Chemical Industry.

Cellulose Anionic Hydrogels Based on Cellulose Nanofibers As Natural Stimulants for Seed Germination and Seedling Growth

Cellulose anionic hydrogels were successfully prepared by dissolving TEMPO-oxidized cellulose nanofibers in NaOH/urea aqueous solution and being cross-linked with epichlorohydrin. The hydrogels exhibited microporous structure and high hydrophilicity, which contribute to the excellent water absorption property. The growth indexes, including the germination rate, root length, shoot length, fresh weight, and dry weight of the seedlings, were investigated. The results showed that cellulose anionic hydrogels with suitable carboxylate contents as plant growth regulators could be beneficial for seed germination and growth. Moreover, they presented preferable antifungal activity during the breeding and growth of the sesame seed breeding. Thus, the cellulose anionic hydrogels with suitable carboxylate contents could be applied as soilless culture mediums for plant growth. This research provided a simple and effective method for the fabrication of cellulose anionic hydrogel and evaluated its application in agriculture.

Evaluation of White Sesame Seed Oil on Glucose Control and Biomarkers of Hepatic, Cardiac, and Renal Functions in Male Sprague-Dawley Rats with Chemically Induced Diabetes

White sesame seed oil (WSSO) has been used in cooking and food preparations for centuries. It has many purported health benefits and may be a promising nutraceutical. The primary purpose of this study was to examine the effects of WSSO on fasting blood glucose (GLU) and insulin (INS) in male Sprague-Dawley rats with chemically induced diabetes. A secondary aim was to explore other hematological biomarkers of hepatic, cardiac, and renal function. Sixty-three male Sprague-Dawley rats were randomized into standard diet groups, normal control (NCON) (n = 21) and diabetic control (DCON) (n = 21), and a diabetic sesame oil (DSO) (n = 21) group, which were fed a diet containing 12% WSSO. Blood samples were analyzed at 0, 30, and 60 days. Differences between groups and across days were assessed with two-way repeated measures analysis of variance. At baseline, GLU and INS were similar in both diabetic groups, mean 248.4 ± 2.8 mg/dL and mean 23.4 ± 0.4 μU/mL, respectively. At 60 days, GLU was significantly (P < .05) higher in DCON (298.0 ± 2.3 mg/dL) compared with DSO (202.1 ± 1.0 mg/dL). INS showed similar favorable trends after WSSO supplementation. Consumption of WSSO significantly improved glucose control and other biomarkers of hepatic stress, as well as cardiac and renal health. WSSO may be a viable functional food to help reduce the detrimental effects of diabetes.

Comparative transcriptome profiling of the fertile and sterile flower buds of a dominant genic male sterile line in sesame (Sesamum indicum L.)

BACKGROUND

Sesame (Sesamum indicum L.) is a globally important oilseed crop with highly-valued oil. Strong hybrid vigor is frequently observed within this crop, which can be exploited by the means of genic male sterility (GMS). We have previously developed a dominant GMS (DGMS) line W1098A that has great potential for the breeding of F₁ hybrids. Although it has been genetically and anatomically characterized, the underlying molecular mechanism for male sterility remains unclear and therefore limits the full utilization of such GMS line. In this study, RNA-seq based transcriptome profiling was carried out in two near-isogenic DGMS lines (W1098A and its fertile counterpart, W1098B) to identify differentially expressed genes (DEGs) related to male sterility.

RESULTS

A total of 1,502 significant DEGs were detected, among which 751 were up-regulated and 751 were down-regulated in sterile flower buds. A number of DEGs were implicated in both ethylene and JA synthesis & signaling pathway; the expression of which were either up- or down-regulated in the sterile buds, respectively. Moreover, the majority of NAC and WRKY transcription factors implicated from the DEGs were up-regulated in sterile buds. By querying the Plant Male Reproduction Database, 49 sesame homologous genes were obtained; several of these encode transcription factors (bHLH089, MYB99, and AMS) that showed reduced expression in sterile buds, thus implying the possible role in specifying or determining tapetal fate and development. The predicted effect of allelic variants on the function of their corresponding DEGs highlighted several Insertions/Deletions (InDels), which might be responsible for the phenotype of sterility/fertility in DGMS lines.

CONCLUSION

The present comparative transcriptome study suggested that both hormone signaling pathway and transcription factors control the male sterility of DGMS in sesame. The results also revealed that several InDels located in DEGs prone to cause loss of function, which might contribute to male sterility. These findings provide valuable genomic resources for a deeper insight into the molecular mechanism underlying DGMS.

Insight into the AP2/ERF transcription factor superfamily in sesame and expression profiling of DREB subfamily under drought stress

BACKGROUND

Sesame is an important oilseed crop mainly grown in inclement areas with high temperatures and frequent drought. Thus, drought constitutes one of the major constraints of its production. The AP2/ERF is a large family of transcription factors known to play significant roles in various plant processes including biotic and abiotic stress responses. Despite their importance, little is known about sesame AP2/ERF genes. This constitutes a limitation for drought-tolerance candidate genes discovery and breeding for tolerance to water deficit.

RESULTS

One hundred thirty-two AP2/ERF genes were identified in the sesame genome. Based on the number of domains, conserved motifs, genes structure and phylogenetic analysis including 5 relatives species, they were classified into 24 AP2, 41 DREB, 61 ERF, 4 RAV and 2 Soloist. The number of sesame AP2/ERF genes was relatively few compared to that of other relatives, probably due to gene loss in ERF and DREB subfamilies during evolutionary process. In general, the AP2/ERF genes were expressed differently in different tissues but exhibited the highest expression levels in the root. Mostly all DREB genes were responsive to drought stress. Regulation by drought is not specific to one DREB group but depends on the genes and the group A6 and A1 appeared to be more actively expressed to cope with drought.

CONCLUSIONS

This study provides insights into the classification, evolution and basic functional analysis of AP2/ERF genes in sesame which revealed their putative involvement in multiple tissue-/developmental stages. Out of 20 genes which were significantly up- /down-regulated under drought stress, the gene AP2si16 may be considered as potential candidate gene for further functional validation as well for utilization in sesame improvement programs for drought stress tolerance.

Effects of Sesaminol Feeding on Brain Aβ Accumulation in a Senescence-Accelerated Mouse-Prone 8

Alzheimer's disease (AD) is characterized by the progressive accumulation of extracellular β-amyloid (Aβ) aggregates. Recently, the senescence-accelerated mouse-prone 8 (SAMP8) model was highlighted as a useful model of age-related AD. Therefore, we used the SAMP8 mouse to investigate the preventive effects of sesame lignans on the onset of AD-like pathology. In preliminary in vitro studies, sesaminol showed the greatest inhibitory effect on Aβ oligomerization and fibril formation relative to sesamin, sesamolin, and sesaminol triglucoside. Hence, sesaminol was selected for further evaluation in vivo. In SAMP8 mice, feed-through sesaminol (0.05%, w/w, in standard chow) administered over a 16 week period reduced brain Aβ accumulation and decreased serum 8-hydroxydeoxyguanosine, an indicator of oxidative stress. Furthermore, sesaminol administration increased the gene and protein expression of ADAM10, which is a protease centrally involved in the non-amyloidogenic processing of amyloid precursor protein. Taken together, these data suggest that long-term consumption of sesaminol may inhibit the accumulation of pathogenic Aβ in the brain.

[Immunoproteomics of non water-soluble allergens from 4 legumes flours: peanut, soybean, sesame and lentil]

Peanut, soybean, sesame and lentil are members of legumes worldwide consumed by human that can induce food allergy in genetically predisposed individuals. Several protein allergens, mainly water-soluble, have been described. We studied the non water-soluble fraction from these 4 food sources using immunoproteomics tools and techniques. Flour extracts were solubilized in detergent and chaotropes and analysed in 1 and 2 dimensional gel electrophoresis (2D). Results showed numerous proteins exhibiting wide ranges of isoelectric points and relative molecular masses. When IgE immunoreactivities of 18 food allergy patients were individually tested in 1 and 2D western-blots, a very diversified IgE repertoire was observed, reflecting extensive cross-reactivities but also co-sensitizations. Besides already well known and characterized allergens, mass spectrometry analysis allowed the identification of 22 allergens undescribed until now: 10 in peanut, 2 in soybean, 3 in sesame and 7 in lentil. Three allergens are legume storage proteins and the others belong to transport proteins, nucleotide binding proteins and proteins involved in the regulation of metabolism. Seven proteins are potentially similar to allergens described in plants and fungi and 11 are not related to any known allergen. Our results contribute to increase the repertoire of legume allergens that may improve the diagnosis, categorize patients and thus provide a better treatment of patients.

Resonance assignments and secondary structure of a phytocystatin from Sesamum indicum

A cDNA encoding a cysteine protease inhibitor, cystatin was cloned from sesame (Sesamum indicum L.) seed. This clone was constructed into an expression vector and expressed in E. coli and purified to homogeneous. The recombinant sesame cystatin (SiCYS) showed effectively inhibitory activity toward C1 cysteine proteases. In order to unravel its inhibitory action from structural point of view, multidimensional heteronuclear NMR techniques were used to characterize the structure of SiCYS. The full (1)H, (15)N, and (13)C resonances of SiCYS were assigned. The secondary structure of SiCYS was identified by using the assigned chemical shifts of (1)H(α), (13)C(α), (13)C(β), and (13)CO through the consensus chemical shift index (CSI). The results of CSI analysis of SiCYS suggest eight β-strands (residues 33-46, 51-61, 63-75, 80-87, 150-155, 157-169, 172-183, and 192-195) and two α-helices (residues 16-30, and 120-135).

Standardized ileal digestibility of proteins and amino acids in sesame expeller and soya bean meal in weaning piglets

Apparent ileal digestibility (AID) of diets containing sesame expeller (SE) and soya bean meal (SBM) was determined using 15 piglets (Genetiporc(®)), weaned at 17 ± 0.4 days with average body weight of 6.4 ± 0.7 kg (Fertilis 20 × G Performance, Genetiporc(®), PIC México, Querétaro, México). Piglets were randomly assigned to three treatments: (i) a reference diet with casein as the sole protein source; (ii) a mixed diet of casein-SE; and (iii) a mixed diet of casein-SBM. The chemical composition of SE and SBM was determined, and AID and standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AAs) were determined for each protein source. SE contained greater quantities of ether extract, neutral detergent fibre, phytic acid, methionine and arginine than SBM. Lysine and proline contents and trypsin inhibitor activity were higher in SBM than in SE. The AID and SID of CP and AA (except for lysine and proline) were similar in SE and SBM. The AID of lysine and proline was higher in SBM than in SE (p < 0.05), and the SID of proline was higher in SE than in SBM (p < 0.05). These findings indicate that SE is an appropriate alternative protein source for early weaned pigs.

Variation in seed fatty acid composition and sequence divergence in the FAD2 gene coding region between wild and cultivated sesame

Sesame germplasm harbors genetic diversity which can be useful for sesame improvement in breeding programs. Seven accessions with different levels of oleic acid were selected from the entire USDA sesame germplasm collection (1232 accessions) and planted for morphological observation and re-examination of fatty acid composition. The coding region of the FAD2 gene for fatty acid desaturase (FAD) in these accessions was also sequenced. Cultivated sesame accessions flowered and matured earlier than the wild species. The cultivated sesame seeds contained a significantly higher percentage of oleic acid (40.4%) than the seeds of the wild species (26.1%). Nucleotide polymorphisms were identified in the FAD2 gene coding region between wild and cultivated species. Some nucleotide polymorphisms led to amino acid changes, one of which was located in the enzyme active site and may contribute to the altered fatty acid composition. Based on the morphology observation, chemical analysis, and sequence analysis, it was determined that two accessions were misnamed and need to be reclassified. The results obtained from this study are useful for sesame improvement in molecular breeding programs.

Seed-specific increased expression of 2S albumin promoter of sesame qualifies it as a useful genetic tool for fatty acid metabolic engineering and related transgenic intervention in sesame and other oil seed crops

The sesame 2S albumin (2Salb) promoter was evaluated for its capacity to express the reporter gusA gene encoding β-glucuronidase in transgenic tobacco seeds relative to the soybean fad3C gene promoter element. Results revealed increased expression of gusA gene in tobacco seed tissue when driven by sesame 2S albumin promoter. Prediction based deletion analysis of both the promoter elements confirmed the necessary cis-acting regulatory elements as well as the minimal promoter element for optimal expression in each case. The results also revealed that cis-regulatory elements might have been responsible for high level expression as well as spatio-temporal regulation of the sesame 2S albumin promoter. Transgenic over-expression of a fatty acid desaturase (fad3C) gene of soybean driven by 2S albumin promoter resulted in seed-specific enhanced level of α-linolenic acid in sesame. The present study, for the first time helped to identify that the sesame 2S albumin promoter is a promising endogenous genetic element in genetic engineering approaches requiring spatio-temporal regulation of gene(s) of interest in sesame and can also be useful as a heterologous genetic element in other important oil seed crop plants in general for which seed oil is the harvested product. The study also established the feasibility of fatty acid metabolic engineering strategy undertaken to improve quality of edible seed oil in sesame using the 2S albumin promoter as regulatory element.

Identification and functional characterization of a flax UDP-glycosyltransferase glucosylating secoisolariciresinol (SECO) into secoisolariciresinol monoglucoside (SMG) and diglucoside (SDG)

BACKGROUND

Lignans are a class of diphenolic nonsteroidal phytoestrogens often found glycosylated in planta. Flax seeds are a rich source of secoisolariciresinol diglucoside (SDG) lignans. Glycosylation is a process by which a glycosyl group is covalently attached to an aglycone substrate and is catalyzed by uridine diphosphate glycosyltransferases (UGTs). Until now, very little information was available on UGT genes that may play a role in flax SDG biosynthesis. Here we report on the identification, structural and functional characterization of 5 putative UGTs potentially involved in secoisolariciresinol (SECO) glucosylation in flax.

RESULTS

Five UGT genes belonging to the glycosyltransferases' family 1 (EC 2.4.x.y) were cloned and characterized. They fall under four UGT families corresponding to five sub-families referred to as UGT74S1, UGT74T1, UGT89B3, UGT94H1, UGT712B1 that all display the characteristic plant secondary product glycosyltransferase (PSPG) conserved motif. However, diversity was observed within this 44 amino acid sequence, especially in the two peptide sequences WAPQV and HCGWNS known to play a key role in the recognition and binding of diverse aglycone substrates and in the sugar donor specificity. In developing flax seeds, UGT74S1 and UGT94H1 showed a coordinated gene expression with that of pinoresinol-lariciresinol reductase (PLR) and their gene expression patterns correlated with SDG biosynthesis. Enzyme assays of the five heterologously expressed UGTs identified UGT74S1 as the only one using SECO as substrate, forming SECO monoglucoside (SMG) and then SDG in a sequential manner.

CONCLUSION

We have cloned and characterized five flax UGTs and provided evidence that UGT74S1 uses SECO as substrate to form SDG in vitro. This study allowed us to propose a model for the missing step in SDG lignan biosynthesis.

Phytosynthesis of nanoscale ZnAl2O4 by using Sesamum (Sesamum indicum L.) optical and catalytic properties

There is a growing concern for the development of alternative environment friendly sustainable methods for the preparation of nanomaterials. Phytosynthesis of nano zinc aluminate by a microwave method using high purity metal nitrates and Sesamum (Sesamum indicum L.) extract is reported in this work. Sesamum (Sesamum indicum L.) extract simplifies the process and provides an alternative method for a simple and economical way of synthesis of nano zinc aluminate. It is also prepared by conventional method for comparison purpose. The obtained nanomaterials were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), nitrogen adsorption/desorption isotherms, diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy. The formation of pure zinc aluminate phase is confirmed by XRD and FT-IR. The change in morphology from nanoplates to nanoporous sheets from the conventional to microwave heating method is clearly shown by HR-SEM. UV-Visible diffuse reflectance spectroscopy (DRS) studies revealed the band gap energy of ZnAl2O4 nanoplates and nanoporous sheets as 4.0 to 4.2 eV respectively. Photoluminescence (PL) emissions are centered at around 480, 519 and 545 nm, respectively. ZnAl2O4 nanoporous sheets prepared by microwave method showed better catalytic activity for the oxidation benzyl alcohol (90%) than ZnAl2O4 nanoplates prepared by conventional method (51%).

Purification and fermentation in vitro of sesaminol triglucoside from sesame cake by human intestinal microbiota

Sesaminol triglucoside (STG), the most abundant lignan glycoside existing in sesame cake/meal, has exhibited various biological activities. However, little information about its in vitro fermentation with intestinal microbiota is available. Therefore, the effect of STG from sesame cake on the fermentation of human fecal microbiota was evaluated. First, high-purity STG was successfully prepared from defatted sesame cake by extraction with 80% ethanol and simple purification procedures of polyamide column chromatography and Toyopearl HW-40S column chromatography. Then the influence of STG on intestinal microbiota was conducted by monitoring bacterial populations and analyzing the concentrations of short-chain fatty acids (SCFA). We found that STG could significantly induce an increase in numbers of Lactobacillus - Enterococcus group and Bifidobacterium in fermentation in vitro with human fecal microbiota, while it did not stimulate the bacterial growth of Eubacterium rectale - Clostridium coccoides group, Clostridium histolyticum group, and Bacteroides - Prevotella group. Furthermore, it was found that concentrations of formic, acetic, propionic, and butyric acids in STG culture increased significantly during the fermentation, and its total SCFA concentration was relatively higher than those of the control and glucose cultures at 6 and 12 h fermentation. Our findings provided further evidence for the importance of human intestinal bacteria in the bioactivity of STG and its metabolites in the maintenance of human health.

The same oleosin isoforms are present in oil bodies of rice embryo and aleurone layer while caleosin exists only in those of the embryo

Oil bodies of similar sizes were observed in the cells of embryo and aleurone layer of rice seeds, and remained their structural integrity in vitro after isolation. Comparably, two abundant oleosin isoforms were found in both preparations of oil bodies isolated from the embryo and the aleurone layer. Immunological detection and mass spectrometric analyses indicated that the two oleosin isoforms, termed oleosin-H and oleosin-L, in the embryo and those in the aleurone layer were identical proteins encoded by the same genes (BAF12898.1 and BAF15387.1 for oleosin-H and oleosin-L, respectively). In contrast, one caleosin was found in oil bodies isolated from the embryo but not those isolated from the aleurone layer. Immunological staining of rice seeds confirms that oleosin is present in both embryo and aleurone layer while caleosin exists only in embryo. Caleosin extracted from oil bodies of rice embryo migrated faster on SDS-PAGE in the presence of Ca(2+), in a manner identical to caleosin extracted from sesame oil bodies. Similar to other known monocot caleosins, the rice caleosin possesses an N-terminal appendix that is absent in dicotyledonous caleosins.

Analysis of expression sequence tags from a full-length-enriched cDNA library of developing sesame seeds (Sesamum indicum)

BACKGROUND

Sesame (Sesamum indicum) is one of the most important oilseed crops with high oil contents and rich nutrient value. However, genetic improvement efforts in sesame could not get benefit from molecular biology technology due to poor DNA and RNA sequence resources. In this study, we carried out a large scale of expressed sequence tags (ESTs) sequencing from developing sesame seeds and further conducted analysis on seed storage products-related genes.

RESULTS

A normalized and full-length enriched cDNA library from 5 ~ 30 days old immature seeds was constructed and randomly sequenced, leading to generation of 41,248 expressed sequence tags (ESTs) which then formed 4,713 contigs and 27,708 singletons with 44.9% uniESTs being putative full-length open reading frames. Approximately 26,091 of all these uniESTs have significant matches to the counterparts in Nr database of GenBank, and 21,628 of them were assigned to one or more Gene ontology (GO) terms. Homologous genes involved in oil biosynthesis were identified including some conservative transcription factors regulating oil biosynthesis such as LEAFY COTYLEDON1 (LEC1), PICKLE (PKL), WRINKLED1 (WRI1) and majority of them were found for the first time in sesame seeds. One hundred and 17 ESTs were identified possibly involved in biosynthesis of sesame lignans, sesamin and sesamolin. In total, 9,347 putative functional genes from developing seeds were identified, which accounts for one third of total genes in the sesame genome. Further analysis of the uniESTs identified 1,949 non-redundant simple sequence repeats (SSRs).

CONCLUSIONS

This study has provided an overview of genes expressed during sesame seed development. This collection of sesame full-length cDNAs covered a wide variety of genes in seeds, in particular, candidate genes involved in biosynthesis of sesame oils and lignans. These EST sequences enriched with full length will contribute to comparative genomic studies on sesame and other oilseed plants and serve as an abundant information platform for functional marker development and functional gene study.

Biosynthetic origin of 2-geranyl-1,4-naphthoquinone and its related anthraquinone in a Sesamum indicum hairy root culture

In order to clarify the biosynthetic origin of 2-geranyl-1,4-naphthoquinone and its biogenetically related anthraquinone, which are possible intermediates of anthrasesamones, [1-(13)C]glucose was administered to a hairy root culture of Sesamum indicum. The labeling patterns of these quinone derivatives indicated that the naphthoquinone ring and geranyl side-chain of geranylnaphthoquinone were respectively biosynthesized through the shikimate and methylerythritol phosphate pathways, and that these quinone derivatives have the same biosynthetic origin.

Accumulation of Cu, Zn, Pb, and Cd in edible parts of four commonly grown crops in two contaminated soils

Soil heavy metal pollution resulting from human activities is causing major concern due to its potential risk. In this study, four crop species with different cultivars were planted in 2 levels (heavily and slightly) of heavy metal contaminated soils, and the accumulation of Cu, Zn, Pb, and Cd in the edible parts of the crops were investigated. Metal concentrations in sesame seeds grown in both soils exceeded both the Chinese Food Hygiene Standard (CFHS) and Codex Alimentarius Commission Standard (CACS), while the metal concentrations in all pepper cultivars in the slightly contaminated soil were below the CFHS and CACS. Other crops were generally in between in both soils. Among the tested crops, the order of soil-plant transfer factor (TF) was: sesame > green soybean > cowpea > pepper. Additionally, old fruit of cowpea contained larger amounts of metals than young fruit. It suggests that sesame should not be planted in the metal contaminated area, while pepper cultivar "Chaobianjiao No.1" may be an alternative to be grown in the slightly contaminated soil. There were differences in individual human susceptibilities to metals. Therefore, a comprehensive risk assessment should consider the frequency, amount and species consumed by human besides metal concentrations in crops.

Ubiquitination of oleosin-H and caleosin in sesame oil bodies after seed germination

Sesame (Sesamum indicum L.) seed oil bodies are composed of triacylglycerols encapsulated by a monolayer of phospholipids embedded with three classes of proteins, oleosin, caleosin and steroleosin. Among proteins extracted from sesame oil bodies after germination, laddering bands higher than the original antigens were recognized by antibodies against oleosin-H (17 kDa) and caleosin (27 kDa), but not those against oleosin-L (15 kDa), steroleosin-A (39 kDa) and steroleosin-B (41 kDa). Regardless the original antigens, the lowest but relatively abundant laddering band (32 kDa) detected by antibodies against oleosin-H and that (42 kDa) detected by antibodies against caleosin were eluted from SDS-PAGE gels, and then subjected to mass spectrometric analyses. The results showed that the 32 kDa and 42 kDa bands were ubiquitinated oleosin-H and caleosin, respectively. The ubiquitination was further confirmed by immunological detection using antibodies against ubiquitin. Ubiquitination sites were found at three lysine residues (130, 143 and 145) of oleosin-H and two lysine residues (165 and 235) of caleosin. Two ubiquitination sites of oleosin-H, Lys(143) and Lys(145), were located in the extra 18-residue segment found only in oleosin-H, but not oleosin-L isoforms.

Elevation of oil body integrity and emulsion stability by polyoleosins, multiple oleosin units joined in tandem head-to-tail fusions

We have successfully created polyoleosins by joining multiple oleosin units in tandem head-to-tail fusions. Constructs encoding recombinant proteins of 1, 3 and 6 oleosin repeats were purposely expressed both in planta and in Escherichia coli. Recombinant polyoleosins accumulated in the seed oil bodies of transgenic plants and in the inclusion bodies of E. coli. Although polyoleosin was estimated to only accumulate to <2% of the total oil body protein in planta, their presence increased the freezing tolerance of imbibed seeds as well as emulsion stability and structural integrity of purified oil bodies; these increases were greater with increasing oleosin repeat number. Interestingly, the hexameric form of polyoleosin also led to an observable delay in germination which could be overcome with the addition of external sucrose. Prokaryotically produced polyoleosin was purified and used to generate artificial oil bodies and the increase in structural integrity of artificial oil bodies-containing polyoleosin was found to mimic those produced in planta. We describe here the construction of polyoleosins, their purification from E. coli, and properties imparted on seeds as well as native and artificial oil bodies. A putative mechanism to account for these properties is also proposed.

Effect of growing Sesamum indicum L. on enhanced dissipation of lindane (1, 2, 3, 4, 5, 6-hexachlorocyclohexane) from soil

The effect of growing Sesamum indicum L. on the dissipation of lindane (gamma-HCH) was studied in spiked soil. For this, S. indicum was grown with four different concentrations of lindane (5, 10, 15, and 20 microg g(-1)). Plant growth, yield, photosynthetic pigments, soluble protein, microbial biomass carbon, lindane uptake, residual lindane concentration in soil and percentage dissipation of lindane from soil were analyzed at 25, 90, and 124 d. The accumulation of lindane in test plants was linearly related to the soil concentration (r2 = 0.897-0.979). At maturity, the accumulation of lindane in S. indicum grown with four spiked concentrations reached up to 7.98, 13.72, 23.71, and 33.29 microg g(-1) dry matter, respectively. There was a marked difference in the dissipation of lindane in vegetated and non-vegetated soils (p < 0.01). After final harvesting, the residual lindane concentrations in four spiked concentrations were reduced by 77.56, 70.12, 62.51, and 58.7%, respectively. Agronomic practice for the onsite application of this species is discussed. Based on the present study, it was calculated that S. indicum could accumulate 2237-2611 mg lindane per acre after 124 d cultivation. S. indicum could thus be used for the phytoremediation of lindane contaminated soil.

Differential tissue distribution of sesaminol triglucoside and its metabolites in rats fed with lignan glycosides from sesame meal with or without nano/submicrosizing

Lignan glycosides are important functional compounds in sesame meal. In the present study, we investigated whether the tissue distribution of nano/submicrosized lignan glycosides from sesame meal (N-LGSM) differs from lignan glycosides from sesame meal (LGSM). LGSM was nano/submicrosized with 0.3 mm zirconia beads as the milling media. The average particle size of the 4% LGSM aqueous suspension reduced rapidly from approximately 2 microm to 200 nm after media milling at an agitation speed of 3600 rpm for 30 min. We examined the tissue distribution of sesaminol triglucoside (ST), the main component in LGSM, in Sprague-Dawley (SD) rats. The concentrations of ST were determined in various tissues and plasma within a 24 h period after oral administration of N-LGSM and LGSM (800 mg/kg of body weight). The results showed that higher concentrations of ST and its metabolites (sesaminol, sesaminol sulfate, and sesaminol glucuronide) were found in N-LGSM compared to those in LGSM in most tissues, especially liver and small intestine. Sesaminol glucuronide was the main metabolite in rats. After 3 h of oral administration, around 70% higher concentration of sesaminol glucuronide was found in N-LGSM compared to that in LGSM. This study clearly showed that LGSM is more bioavailable after nano/submicrosizing.

Hypersensitive response of Sesamum prostratum Retz. elicitated by Fusarium oxysporum f. sesame (Schelt) Jacz Butler

Aim of this study was to investigate the intensity and timing of the ROS formation, lipid peroxidation and expression of antioxidant enzymes as initial responses of calli of Sesamum prostratum (SP) against Fusarium oxysporum f. sesame crude toxin metabolite of varying concentrations. 2,4 dichlorophenoxy acetic acid (2,4-D) / coconut milk combinations were found to be more efficient among different hormonal regimes (2,4 -D, 2,4-D/casein hydrosylate and 2,4-D/ coconut milk). The concentration of hydrogen peroxide and lipid peroxidation were higher (13.2 and 5.7-folds, respectively) after 6 h in the treated callus confirmed the oxidative stress. An increase in total phenolics was also detected in inoculated callus. Increased activity of antioxidative enzymes viz., NADPH oxidase and superoxide dismutase (SOD) corroborate with the high level of ROSs, such as O2*- and H2O2. The poor activity of catalase confirmed the oxidative burst in the callus leading to necrosis. Activity of peroxidase was at par with total phenolics. Similarly, phenylalanine ammonia lyase (PAL) also showed high activity revealing the active phase in the synthesis of secondary metabolites in the plant. The oxidative burst generated in the interaction between Sesamum and F. oxysporum f. sesame toxin might be the first line of defense by the host mounted against the invading necrotrophic pathogen. The results suggested that the rapid production of reactive oxygen species in the callus in response to fungal toxin had been proposed to orchestrate the establishment of different defensive barriers against the pathogens.