Dataset Information

Genotypic and Environmental Effects on Tocopherol Content in Almond.

ABSTRACT: Almond is the most important nut species worldwide and almond kernels show the highest levels of tocopherols among all nuts. In almond, tocopherols not only play a substantial role as a healthy food for human consumption, but also in protecting lipids against oxidation and, thus, lengthening the storage time of almond kernels. The main tocopherol homologues detected in almond in decreasing content and biological importance are ?-, ?-, ?-, and ?-tocopherol. Tocopherol concentration in almond depends on the genotype and the environment, such as the climatic conditions of the year and the growing management of the orchard. The range of variability for the different tocopherol homologues is of 335-657 mg/kg of almond oil for ?-, 2-50 for ?-, and 0.1-22 for ?-tocopherol. Drought and heat have been the most important stresses affecting tocopherol content in almond, with increased levels at higher temperatures and in water deficit conditions. The right cultivar and the most appropriate growing conditions may be selected to obtain crops with effective kernel storage and for the most beneficial effects of almond consumption for human nutrition and health.

SUBMITTER: Kodad O

PROVIDER: S-EPMC5789316 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Genotypic and Environmental Effects on Tocopherol Content in Almond.

Kodad Ossama O Socias I Company Rafel R Alonso José M JM

Antioxidants (Basel, Switzerland) 20180105 1

Almond is the most important nut species worldwide and almond kernels show the highest levels of tocopherols among all nuts. In almond, tocopherols not only play a substantial role as a healthy food for human consumption, but also in protecting lipids against oxidation and, thus, lengthening the storage time of almond kernels. The main tocopherol homologues detected in almond in decreasing content and biological importance are α-, γ-, δ-, and β-tocopherol. Tocopherol concentration in almond depe ...[more]

PMID: 29303980

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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: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:Soybean seeds are primary sources of natural tocopherols used by the food and pharmaceutical industries, owing to their beneficial impacts on human health. Selection for higher tocopherol contents in seeds along with other desirable traits is an important goal in soybean breeding. In order to identify the genomic loci and candidate genes controlling tocopherol content in soybean seeds, the bulked-segregant analysis technique was performed using a natural population of soybean consisting of 1525 accessions. We constructed the bulked-segregant analysis based on 98 soybean accessions that showed extreme phenotypic variation for the target trait, consisting of 49 accessions with extremely-high and 49 accessions with extremely-low tocopherol content. A total of 144 variant sites and 109 predicted genes related to tocopherol content were identified, in which a total of 83 genes were annotated by the gene ontology functions. Furthermore, 13 enriched terms (p < 0.05) were detected, with four of them found to be highly enriched: response to lipid, response to abscisic acid, transition metal ion transmembrane transporter activity, and double-stranded DNA binding. Especially, six candidate genes were detected at 41.8-41.9 Mb genomic hotspots on chromosome 5 based on ANNOtate VARiation analysis. Among the genes, only Glyma.05G243400 carried a non-synonymous mutation that encodes a "translation elongation factor EF1A or initiation factor IF2gamma family protein" was identified. The haplotype analysis confirmed that Glyma.05G243400 exhibited highly significant variations in terms of tocopherol content across multiple experimental locations, suggesting that it can be the key candidate gene regulating soybean seed tocopherols. The present findings provide novel gene resources related to seed tocopherols for further validation by genome editing, functional characterization, and genetic improvement targeting enhanced tocopherol composition in soybean molecular breeding.

Dataset Information

Genotypic and Environmental Effects on Tocopherol Content in Almond.

Publications

Genotypic and Environmental Effects on Tocopherol Content in Almond.

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