Functional Characterization of Flax Fatty Acid Desaturase FAD2 and FAD3 Isoforms Expressed in Yeast Reveals a Broad Diversity in Activity
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Linum
Fatty acid desaturase
Linolenic acid
alpha-Linolenic acid
Abstract In the course of a breeding programme for high‐linolenic‐acid linseed (oilflax, Linum usitatissimum L.) doubled‐haploid lines (DH‐lines) of three F 1 hybrids were generated using an anther‐culture technique. A total of 82 DH‐lines were generated and multiplied in 1993, of which 39 were suitable for testing in a repeated field trial in 1994. Yield, fat content and fatty‐acid composition were determined. The yield of the DH‐lines was not significantly different from that of respective mid‐parent values. Fatty‐acid composition and fat content showed remarkable variation, and DH‐lines exceeded cross parents in some cases for both fat content and linolenic‐acid proportion. Superior DH‐lines surpassed mid‐parent linolenic‐acid‐content values by 4.5% and fat content by 1.9%. The results indicate that anther culture is a useful tool in linseed breeding.
Linum
Linolenic acid
Doubled haploidy
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Fatty acid desaturase
Linolenic acid
alpha-Linolenic acid
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One major locus ( Fan ) and several minor loci have been shown to contribute to the linolenic acid level in soybean [ Glycine max (L.) Merr.] seeds. The Fan gene encodes a microsomal omega‐3 fatty acid desaturase ( Arabidopsis FAD3 homolog), and soybeans contain three FAD3 genes. The objective of this work was to characterize candidate soybean FAD3 genes from low linolenic acid soybean lines and associate those alleles with the trait. Mutations in two of the three soybean FAD3 genes were identified, and genotypes with the mutant alleles conferred a reduction of over two thirds of the linolenic acid present in the seed. The two mutant genes contributed unequally but additively to the phenotype. The results demonstrated that the mutant genotype can be identified with mutation‐specific molecular markers in the F 2 generation, and the low linolenic acid trait will be stably inherited in subsequent generations.
Linolenic acid
Fatty acid desaturase
alpha-Linolenic acid
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Genetic effects and temperature during the reproductive period for unsaturated fatty acids in soybean [ Glycine max (L.) Merr.] seed oil affect oil composition. Increasing oleic and reducing linolenic acids are desirable to improve oil for food and other uses. The objective of this study was to access the environmental effect on fatty acids of seed oil for seventeen soybean genotypes with normal and modified fatty acid profiles. Stability coefficients (b values) were calculated from the regression of fatty acid level on average temperature over the final 30 d of the reproductive period across 10 environments. Mid‐oleic acid genotypes were generally less stable for oleic acid content than genotypes with reduced oleic acid. Significant differences, however, were found for oleic acid stability among mid‐oleic acid genotypes. Mid‐oleic acid lines N98–4445A and N97–3363–4 were the most unstable among the 17 genotypes with stability coefficients of 3.28 and 2.53, respectively. However, the higher oleic acid line M23 was relatively stable in oleic acid with a stability coefficient of 0.13 over environments. IA 3017 at 10 g kg −1 was the most stable in linolenic acid content across environments while progressively higher linolenic acid genotypes were less stable. Soybean lines similar to M23 and IA 3017 will be essential to develop increased oleic acid and reduced linolenic acid cultivars to ensure consistent production of soybean oil with the desired fatty acid levels.
Linolenic acid
Soybean oil
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Nine lines of T_(2) generation of marker-free transgenic soybeans of Pudou 8008 with Delta~(6)-fatty acid desaturase gene were characterized.PCR and Southern blot indicated that the selective marker gene(bar) had been removed from some transgenic soybean progenies,while Delta~(6)-fatty acid desaturase gene was still in some progenies of these transgenic soybean lines.Northern blot showed that the Delta~(6)-fatty acid desaturase gene could be transcribed in the marker-free transgenic soybean lines.Gas chromatographic analysis showed that six transgenic soybean lines could produce gamma-linolenic acid.
Fatty acid desaturase
Linolenic acid
Southern blot
alpha-Linolenic acid
Northern blot
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Linum
Linolenic acid
alpha-Linolenic acid
gamma-Linolenic acid
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Abstract BACKGROUND Soybean seeds contain 18–24% lipids, which are made up of 85% polyunsaturated fatty acids. Two of these (linoleic and linolenic acids) comprise essential fatty acids that are not synthesized in humans and animals. Linolenic acid plays a vital role in the maintenance of brain function and is a source of docosahexaenoic acid for retinal and nerve tissue, with its physiological functions being a focus of attention. RESULTS We developed mutant soybean populations via gamma irradiation of Korean cultivars Danbaek and Daepung and evaluated the linolenic acid content of 78 and 154 M 9 mutant progenies. We selected the four mutant lines with the highest linolenic acid contents based on 2 years of investigation of fatty acids. The selected mutant lines had linolenic acid contents that were 33.9% to 67.7% higher than those of the original cultivars and exhibited increased fatty acid desaturase ( FAD ) gene expression levels during seed development. We also identified nucleotide polymorphisms of FAD genes in the four mutant lines. CONCLUSION The present study found that linolenic acid content is related to significantly increased expression levels of the FAD3C and FAD3D genes in the endoplasmic reticulum, which was uncovered by radiation mutation breeding of soybean. © 2019 Society of Chemical Industry
Linolenic acid
Fatty acid desaturase
alpha-Linolenic acid
gamma-Linolenic acid
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Two flax (Linum usitatissimum L.) mutants having reduced linolenic acid content in their seed oil (M1589 = 19.1% linolenic; M1722 = 23.4% linolenic) were crossed to determine whether further reductions could be achieved by recombination of the mutant genes. Extensive transgressive segregation was evident in the F 2 for both linolenic acid (1.2–36.6%) and linoleic acid (14.7–55.2%), which were strongly negatively correlated (r = −0.97). F 2 plants homozygous for both the M1589 and M1722 mutations had very low levels of linolenic acid (<2%) and high levels of linoleic acid (>46%).Key words: Flax, linseed, Linum usitatissimum, linoleic acid, linolenic acid, seed oil
Linum
Linolenic acid
alpha-Linolenic acid
gamma-Linolenic acid
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Soybean [ Glycine max (L.) Merr.] oil is the major edible vegetable oil that has a high endogenous level of linolenic acid. Natural oxidation of linolenic acid produces chemical intermediates which cause poor oil flavor. An expensive hydrogenation process is required to lower the concentration of linolenic acid to an acceptable level. Because of this, a plant breeding project was begun to reduce the percentage of linolenic acid in soybean oil. The selection criterion was high oleic acid percentage which is negatively correlated with linolenic acid percentage. A soybean population was developed by mating six lines with relatively high oleic acid percentage to the genetic male‐sterile ( ms 1 ms 1 ) maintainer line, N69‐2774. Four cycles of recurrent mass selection for increased oleic acid were conducted in the population. In the fourth cycle, mass selection was followed by within half‐sib family selection. In each cycle segregation of the male‐sterile trait within the population permitted cross matings to occur naturally between selected male‐sterile and male‐fertile plants by insect pollination. Progress due to selection was evaluated by growing the selected lines from each cycle in replicated tests in six environments. Results of these tests show that oleic acid percentage of the soybean oil increased linearly from 24.8 to 33.0%. The correlated trait, linolenic acid percentage, decreased linearly from 7.8 to 6.3%. In addition, the linoleic acid level declined from 53.3 to 47.0%. Changes in stearic acid percentage were not correlated with cycles of selection. Realized heritability (h 2 ) for oleic acid percentage was 0.21 ± 0.06. There was a significant interaction between environments and cycle populations. The effect of that interaction, however, was expressed as differences in the magnitude of oleic acid percentages in the different environments rather than differences in ranking. Hence, selection for oleic acid percentage in soybean oil may not be compromised severely by environmental interaction.
Linolenic acid
Stearic acid
Soybean oil
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