Dataset Information

Rapid Estimation of Tocopherol Content in Linseed and Sunflower Oils-Reactivity and Assay.

ABSTRACT: The reactivity of tocopherols with 2,2-diphenyl-1-picrylhydrazyl (DPPH) was studied in model systems in order to establish a method for quantifying vitamin E in plant oils. The method was optimized with respect to solvent composition of the assay medium, which has a large influence on the course of reaction of tocopherols with DPPH. The rate of reaction of ?-tocopherol with DPPH is higher than that of ?-tocopherol in both protic and aprotic solvents. In ethyl acetate, routinely applied for the analysis of antioxidant potential (AOP) of plant oils, reactions of tocopherols with DPPH are slower and concentration of tocopherols in the assay has a large influence on their molar reactivity. In 2-propanol, however, two electrons are exchanged for both ?- and ?-tocopherols, independent of their concentration. 2-propanol is not toxic and is fully compatible with polypropylene labware. The chromatographically determined content of tocopherols and their molar reactivity in the DPPH assay reveal that only tocopherols contribute to the AOP of sunflower oil, whereas the contribution of tocopherols to the AOP of linseed oil is 75%. The DPPH assay in 2-propanol can be applied for rapid and cheap estimation of vitamin E content in plant oils where tocopherols are major antioxidants.

SUBMITTER: Prevc T

PROVIDER: S-EPMC6332417 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

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Rapid Estimation of Tocopherol Content in Linseed and Sunflower Oils-Reactivity and Assay.

Prevc Tjaša T Levart Alenka A Cigić Irena Kralj IK Salobir Janez J Ulrih Nataša Poklar NP Cigić Blaž B

Molecules (Basel, Switzerland) 20150813 8

The reactivity of tocopherols with 2,2-diphenyl-1-picrylhydrazyl (DPPH) was studied in model systems in order to establish a method for quantifying vitamin E in plant oils. The method was optimized with respect to solvent composition of the assay medium, which has a large influence on the course of reaction of tocopherols with DPPH. The rate of reaction of α-tocopherol with DPPH is higher than that of γ-tocopherol in both protic and aprotic solvents. In ethyl acetate, routinely applied for the a ...[more]

PMID: 26287138

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Project description:BACKGROUND: Tocopherols are natural antioxidants with both in vivo (vitamin E) and in vitro activity. Sunflower seeds contain predominantly alpha-tocopherol (>90% of total tocopherols), with maximum vitamin E effect but lower in vitro antioxidant action than other tocopherol forms such as gamma-tocopherol. Sunflower germplasm with stable high levels of gamma-tocopherol (>85%) has been developed. The trait is controlled by recessive alleles at a single locus Tph2 underlying a gamma-tocopherol methyltransferase (gamma-TMT). Additionally, unstable expression of increased gamma-tocopherol content in the range from 5 to 85% has been reported. The objective of this research was to determine the genetic basis of unstable expression of high gamma-tocopherol content in sunflower seeds. RESULTS: Male sterile plants of nuclear male sterile line nmsT2100, with stable high gamma-tocopherol content, were crossed with plants of line IAST-1, with stable high gamma-tocopherol content but derived from a population that exhibited unstable expression of the trait. F2 seeds showed continuous segregation for gamma-tocopherol content from 1.0 to 99.7%. Gamma-tocopherol content in F2 plants (average of 24 individual F3 seeds) segregated from 59.4 to 99.4%. A genetic linkage map comprising 17 linkage groups (LGs) was constructed from this population using 109 SSR and 20 INDEL marker loci, including INDEL markers for tocopherol biosynthesis genes. QTL analysis revealed a major QTL on LG 8 that corresponded to the gamma-TMT Tph2 locus, which suggested that high gamma-tocopherol lines nmsT2100 and IAST-1 possess different alleles at this locus. Modifying genes were identified at LGs 1, 9, 14 and 16, corresponding in most cases with gamma-TMT duplicated loci. CONCLUSIONS: Unstable expression of high gamma-tocopherol content is produced by the effect of modifying genes on tph2a allele at the gamma-TMT Tph2 gene. This allele is present in line IAST-1 and is different to allele tph2 present in line nmsT2100, which is not affected by modifying genes. No sequence differences at the gamma-TMT gene were found associated to allelic unstability. Our results suggested that modifying genes are mostly epistatically interacting gamma-TMT duplicated loci.

Project description:BACKGROUND: Improvement of ?-tocopherol content is an important breeding aim to increase the nutritional value of crops. Several efforts have been conducted to improve the ?-tocopherol content in soybean [Glycine max (L.) Merr.] through transgenic technology by overexpressing genes related to ?-tocopherol biosynthesis or through changes to crop management practices. Varieties with high ?-tocopherol content have been identified in soybean germplasms. The heritability of this trait has been characterized in a cross between high ?-tocopherol variety Keszthelyi Aproszemu Sarga (KAS) and low ?-tocopherol variety Ichihime. In this study, the genetic mechanism of the high ?-tocopherol content trait of KAS was elucidated. RESULTS: Through QTL analysis and fine mapping in populations from a cross between KAS and a Japanese variety Ichihime, we identified ?-TMT3, which encodes ?-tocopherol methyltransferase, as a candidate gene responsible for high ?-tocopherol concentration in KAS. Several nucleotide polymorphisms including two nonsynonymous mutations were found in the coding region of ?-TMT3 between Ichihime and KAS, but none of which was responsible for the difference in ?-tocopherol concentration. Therefore, we focused on transcriptional regulation of ?-TMT3 in developing seeds and leaves. An F5 line that was heterozygous for the region containing ?-TMT3 was self-pollinated. From among the progeny, plants that were homozygous at the ?-TMT3 locus were chosen for further evaluation. The expression level of ?-TMT3 was higher both in developing seeds and leaves of plants homozygous for the ?-TMT3 allele from KAS. The higher expression level was closely correlated with high ?-tocopherol content in developing seeds. We generated transgenic Arabidopsis plants harboring GUS gene under the control of ?-TMT3 promoter from KAS or Ichihime. The GUS activity assay showed that the activity of ?-TMT3 promoter from KAS was higher than that of Ichihime. CONCLUSIONS: The genetic variation in ?-TMT3, which plays a major role in determining ?-tocopherol concentration, provides significant information about the regulation of tocopherol biosynthesis in soybean seeds. This knowledge will help breeding programs to develop new soybean varieties with high ?-tocopherol content.

Project description:Prediction of hybrid performance using incomplete factorial mating designs is widely used in breeding programs including different heterotic groups. Based on the general combining ability (GCA) of the parents, predictions are accurate only if the genetic variance resulting from the specific combining ability is small and both parents have phenotyped descendants. Genomic selection (GS) can predict performance using a model trained on both phenotyped and genotyped hybrids that do not necessarily include all hybrid parents. Therefore, GS could overcome the issue of unknown parent GCA. Here, we compared the accuracy of classical GCA-based and genomic predictions for oil content of sunflower seeds using several GS models. Our study involved 452 sunflower hybrids from an incomplete factorial design of 36 female and 36 male lines. Re-sequencing of parental lines allowed to identify 468,194 non-redundant SNPs and to infer the hybrid genotypes. Oil content was observed in a multi-environment trial (MET) over 3 years, leading to nine different environments. We compared GCA-based model to different GS models including female and male genomic kinships with the addition of the female-by-male interaction genomic kinship, the use of functional knowledge as SNPs in genes of oil metabolic pathways, and with epistasis modeling. When both parents have descendants in the training set, the predictive ability was high even for GCA-based prediction, with an average MET value of 0.782. GS performed slightly better (+0.2%). Neither the inclusion of the female-by-male interaction, nor functional knowledge of oil metabolism, nor epistasis modeling improved the GS accuracy. GS greatly improved predictive ability when one or both parents were untested in the training set, increasing GCA-based predictive ability by 10.4% from 0.575 to 0.635 in the MET. In this scenario, performing GS only considering SNPs in oil metabolic pathways did not improve whole genome GS prediction but increased GCA-based prediction ability by 6.4%. Our results show that GS is a major improvement to breeding efficiency compared to the classical GCA modeling when either one or both parents are not well-characterized. This finding could therefore accelerate breeding through reducing phenotyping efforts and more effectively targeting for the most promising crosses.

Dataset Information

Rapid Estimation of Tocopherol Content in Linseed and Sunflower Oils-Reactivity and Assay.

Publications

Rapid Estimation of Tocopherol Content in Linseed and Sunflower Oils-Reactivity and Assay.

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