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New sources of soybean seed meal and oil composition traits identified through TILLING.

Dierking EC, Bilyeu KD - BMC Plant Biol. (2009)

Bottom Line: Four mutations in independent lines were identified in the raffinose synthase gene RS2; two mutations resulted in amino acid mutations and one resulted in an altered seed oligosaccharide phenotype.Molecular marker assays were developed to reliably detect the inheritance of the mutant alleles and can be used in efficient breeding for these desired seed phenotypes.Our results serve as the first demonstration of the identification of soybean mutants controlling seed phenotypes discovered through the reverse genetics technique TILLING.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Missouri-Columbia, Division of Plant Sciences, 110 Waters Hall, Columbia, MO 65211, USA. Emily.Dierking@mizzou.edu

ABSTRACT

Background: Several techniques are available to study gene function, but many are less than ideal for soybean. Reverse genetics, a relatively new approach, can be utilized to identify novel mutations in candidate genes; this technique has not produced an allelic variant with a confirmed phenotype in soybean. Soybean raffinose synthase genes and microsomal omega-6 fatty acid desaturase genes were screened for novel alleles in mutagenized soybean populations.

Results: Four mutations in independent lines were identified in the raffinose synthase gene RS2; two mutations resulted in amino acid mutations and one resulted in an altered seed oligosaccharide phenotype. The resulting phenotype was an increase in seed sucrose levels as well as a decrease in both raffinose and stachyose seed oligosaccharide levels. Three mutations in independent lines were identified in the omega-6 fatty acid desaturase gene FAD2-1A; all three mutations resulted in missense amino acid mutations and one resulted in an altered seed fatty acid profile that led to an increase in oleic acid and a decrease in linoleic acid in the seed oil.

Conclusion: The oligosaccharide phenotype controlled by the novel RS2 allele is similar to previously observed seed oligosaccharide phenotypes in RS2 mutant (PI 200508) allele-containing lines. Due to the anti-nutritional characteristics of raffinose and stachyose, this represents a positive change in seed composition. The fatty acid phenotype controlled by the novel FAD2-1A allele controls an increase in oleic acid in the seed oil, a phenotype also observed in a line previously characterized to have a allele of the FAD2-1A gene. Molecular marker assays were developed to reliably detect the inheritance of the mutant alleles and can be used in efficient breeding for these desired seed phenotypes. Our results serve as the first demonstration of the identification of soybean mutants controlling seed phenotypes discovered through the reverse genetics technique TILLING.

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Inheritance of S117N alleles of FAD2-1A results in increased mean oleic acid and decreased linoleic acid soybean seed oil. Soybean lines with contrasting homozygous mutant or wild-type FAD2-1A alleles were developed from a cross of line 17D with Williams 82. Homozygous mutant S117N FAD2-1A lines (FAD2-1aa) and homozygous wild-type (FAD2-1AA) lines were grown in the field in 2008. Fatty acid profiles were determined for individual seeds and histograms of mutant (spotted) or wild-type (diagonal lines) represent the mean relative palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2), and linolenic acid (18:3) content of the oil. Error bars represent plus and minus one standard deviation of the mean.
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Figure 6: Inheritance of S117N alleles of FAD2-1A results in increased mean oleic acid and decreased linoleic acid soybean seed oil. Soybean lines with contrasting homozygous mutant or wild-type FAD2-1A alleles were developed from a cross of line 17D with Williams 82. Homozygous mutant S117N FAD2-1A lines (FAD2-1aa) and homozygous wild-type (FAD2-1AA) lines were grown in the field in 2008. Fatty acid profiles were determined for individual seeds and histograms of mutant (spotted) or wild-type (diagonal lines) represent the mean relative palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2), and linolenic acid (18:3) content of the oil. Error bars represent plus and minus one standard deviation of the mean.

Mentions: The inheritance of the S117N mutant FAD2-1A allele from line 17D and the fatty acid phenotype was evaluated in selected homozygous progeny derived from a cross of Williams 82 with line 17D. Molecular marker assays specific for the S117N mutant FAD2-1A allele from 17D were designed and validated. Six independent F3 plants homozygous for the 17D mutant alleles and five independent homozygous wild-type plants were grown to produce seed in a field environment. Fatty acid analysis on the resulting F4 seeds demonstrated significantly higher mean oleic acid levels for those seeds which were homozygous for the mutant S117N allele of FAD2-1A (Figure 6). The mean linoleic acid level for the FAD2-1A mutant seeds was significantly lower than the wild-type FAD2-1A seeds. Overall, the significant change in oleic acid content and the concomitant decrease in linoleic acid content is consistent with the S117N alleles of FAD2-1A responsible for disrupting at least part of the seed expressed omega-6 fatty acid desaturase enzymatic capacity.


New sources of soybean seed meal and oil composition traits identified through TILLING.

Dierking EC, Bilyeu KD - BMC Plant Biol. (2009)

Inheritance of S117N alleles of FAD2-1A results in increased mean oleic acid and decreased linoleic acid soybean seed oil. Soybean lines with contrasting homozygous mutant or wild-type FAD2-1A alleles were developed from a cross of line 17D with Williams 82. Homozygous mutant S117N FAD2-1A lines (FAD2-1aa) and homozygous wild-type (FAD2-1AA) lines were grown in the field in 2008. Fatty acid profiles were determined for individual seeds and histograms of mutant (spotted) or wild-type (diagonal lines) represent the mean relative palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2), and linolenic acid (18:3) content of the oil. Error bars represent plus and minus one standard deviation of the mean.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2719642&req=5

Figure 6: Inheritance of S117N alleles of FAD2-1A results in increased mean oleic acid and decreased linoleic acid soybean seed oil. Soybean lines with contrasting homozygous mutant or wild-type FAD2-1A alleles were developed from a cross of line 17D with Williams 82. Homozygous mutant S117N FAD2-1A lines (FAD2-1aa) and homozygous wild-type (FAD2-1AA) lines were grown in the field in 2008. Fatty acid profiles were determined for individual seeds and histograms of mutant (spotted) or wild-type (diagonal lines) represent the mean relative palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2), and linolenic acid (18:3) content of the oil. Error bars represent plus and minus one standard deviation of the mean.
Mentions: The inheritance of the S117N mutant FAD2-1A allele from line 17D and the fatty acid phenotype was evaluated in selected homozygous progeny derived from a cross of Williams 82 with line 17D. Molecular marker assays specific for the S117N mutant FAD2-1A allele from 17D were designed and validated. Six independent F3 plants homozygous for the 17D mutant alleles and five independent homozygous wild-type plants were grown to produce seed in a field environment. Fatty acid analysis on the resulting F4 seeds demonstrated significantly higher mean oleic acid levels for those seeds which were homozygous for the mutant S117N allele of FAD2-1A (Figure 6). The mean linoleic acid level for the FAD2-1A mutant seeds was significantly lower than the wild-type FAD2-1A seeds. Overall, the significant change in oleic acid content and the concomitant decrease in linoleic acid content is consistent with the S117N alleles of FAD2-1A responsible for disrupting at least part of the seed expressed omega-6 fatty acid desaturase enzymatic capacity.

Bottom Line: Four mutations in independent lines were identified in the raffinose synthase gene RS2; two mutations resulted in amino acid mutations and one resulted in an altered seed oligosaccharide phenotype.Molecular marker assays were developed to reliably detect the inheritance of the mutant alleles and can be used in efficient breeding for these desired seed phenotypes.Our results serve as the first demonstration of the identification of soybean mutants controlling seed phenotypes discovered through the reverse genetics technique TILLING.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Missouri-Columbia, Division of Plant Sciences, 110 Waters Hall, Columbia, MO 65211, USA. Emily.Dierking@mizzou.edu

ABSTRACT

Background: Several techniques are available to study gene function, but many are less than ideal for soybean. Reverse genetics, a relatively new approach, can be utilized to identify novel mutations in candidate genes; this technique has not produced an allelic variant with a confirmed phenotype in soybean. Soybean raffinose synthase genes and microsomal omega-6 fatty acid desaturase genes were screened for novel alleles in mutagenized soybean populations.

Results: Four mutations in independent lines were identified in the raffinose synthase gene RS2; two mutations resulted in amino acid mutations and one resulted in an altered seed oligosaccharide phenotype. The resulting phenotype was an increase in seed sucrose levels as well as a decrease in both raffinose and stachyose seed oligosaccharide levels. Three mutations in independent lines were identified in the omega-6 fatty acid desaturase gene FAD2-1A; all three mutations resulted in missense amino acid mutations and one resulted in an altered seed fatty acid profile that led to an increase in oleic acid and a decrease in linoleic acid in the seed oil.

Conclusion: The oligosaccharide phenotype controlled by the novel RS2 allele is similar to previously observed seed oligosaccharide phenotypes in RS2 mutant (PI 200508) allele-containing lines. Due to the anti-nutritional characteristics of raffinose and stachyose, this represents a positive change in seed composition. The fatty acid phenotype controlled by the novel FAD2-1A allele controls an increase in oleic acid in the seed oil, a phenotype also observed in a line previously characterized to have a allele of the FAD2-1A gene. Molecular marker assays were developed to reliably detect the inheritance of the mutant alleles and can be used in efficient breeding for these desired seed phenotypes. Our results serve as the first demonstration of the identification of soybean mutants controlling seed phenotypes discovered through the reverse genetics technique TILLING.

Show MeSH
Related in: MedlinePlus