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DFLP, SSCP, and SSR markers for Δ9-stearoyl-acyl carrier protein desaturases strongly expressed in developing seeds of sunflower: intron lengths are polymorphic among elite inbred lines (1998)

Hongtrakul, Vipa ; Slabaugh, Mary B. ; Knapp, Steven J.

Springer

Molecular breeding 4 (1998), S. 195-203

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ISSN: 1572-9788

Keywords: Helianthus annuus ; L. ; simple sequence repeats ; single-strand conformational polymorphisms ; stearoyl-ACP desaturase ; stearic acid ; oleic acid

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Stearoyl-acyl carrier protein desaturase (SAD, EC 1.14.99.6) produces oleic acid (18:1 Δ9) by desaturating 18:0. SAD genes have been targets for breeding and engineering oilseed crops with increased stearic acid (18:0). Our aim was to clone, describe, and develop genetic markers for the SAD genes of sunflower (Helianthus annuus L.). Nineteen SAD cDNA clones were partially sequenced and found to belong to two groups. Full-length cDNAs from each group (SAD6 and SAD17) were completely sequenced. The amino acid identity of SAD6 and SAD17 was 89%. Both genes were strongly expressed in developing seeds, moderately expressed in leaves and flowers, and weakly expressed in cotyledons, roots, and stems. One intron was found in SAD6 and two introns were found in SAD17. The SAD introns from two inbred lines (HA370 and HA372) were sequenced and found to vary in length and nucleotide sequence. The length variants were caused by monomeric repeat length differences, insertions, and deletions. Three long poly-T repeats (T9 to T39) were found in one of the SAD17 introns. Three short adjacent CA repeats were found in the 5′-untranslated region of SAD6. DNA fragment length polymorphism (DFLP), single-strand conformational polymorphism (SSCP), and simple sequence repeat (SSR) markers were developed for SAD6 and SAD17 by developing primers to flank introns or the CA repeats. Two of six DFLP, four of six SSCP, and one of two SSR markers were polymorphic among eight elite inbred lines. The polymorphic information contents for DFLP, SSCP, and SSR markers were 0.18, 0.37, and 0.30, respectively. Most of the polymorphisms were caused by intron fragment length polymorphisms. Introns may be an excellent source of hypervariable markers in sunflower and other crop plants.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009646720400

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2

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Marker-Assisted Selection as a Strategy for Increasing the Probability of Selecting Superior Genotypes (1998)

Knapp, Steven J.

Springer

Crop science 38 (1998), S. 1164-1174

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ISSN: 1435-0653

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Pr MAS ). This paramater was used to estimate the cost efficiency of MAS relative to phenotypic selection (E c ). Pr MAS and E c functions of heritability (h 2), heritability of a MAS index (h 2 I), the phenotypic selection threshold (i), the genotypic superiority threshold (g), and p=σ2 M/σ2 G, where σ2 Mis additive genetic variance associated with markers and σ2 Gis additive genetic variance. h 2 I increases as pincreases. Heritability can be increased to 1.0 by increasing p to 1.0; however, estimated marker effects (^) and true quantitative trait locus effects p must be perfectly correlated to achieve this in practice. Pr MAS increases throughout the range of p when i≥g, decreases g increases, and increases as i increases for most p. The frequency of superior genotypes among selected progeny increases as selection intensity increases. E c ranged from 1.0 to 16.7 for iand g from 1. to 2.326, h 2 from 0.1 to 1.0, and p from 0.0 to 1.0; thus, a breeder using phenotypic selection must test 1.0 to 16.7 times more progeny than a breeder using MAS to be assured of selecting one or more superior genotypes. E c increases as g or i increase and h 2 decreases and increases as p increases when i=g. E c predicts that MAS substantially decreases the resources needed to accomplish a selection goal for a low to moderate heritability trait when the selection goal and the selection intensity are high.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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3

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Ancestral Origins and Genetic Diversity of Cultivated Sunflower: Coancestry Analysis of Public Germplasm (1998)

Cheres, Mercy T. ; Knapp, Steven J.

Springer

Crop science 38 (1998), S. 1476-1482

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ISSN: 1435-0653

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Cultivated sunflower (Helianthus annus L.) seems to have originated from a small number of ancestral germplasm sources. The number of key ancestors and how much each ancestor has contributed to the genetic diversity of public inbred lines is not known. We used coancestry analysis to assess this. The pedigrees of publicly released inbred lines were traced as far back as possible. Coancestries were estimated among 106 oilseed and 50 confectionery inbred lines and 157 ancestral germplasm sources. Cluster and principal component analyses of the coancestry matrix separated lines into broad market (oilseed versus confectionery) and fertility restorer (restorer versus maintainer) classes. There were four subgroups among oilseed maintainer lines (B-lines) and three subgroups among oilseed restorer lines (R-lines); however, the R-line subgroups were heterogeneous and the boundaries between them were not sharp. These B and R subgroups may constitute heterotic groups. Sixty-eight percent of oilseed R-line diversity traced to seven germplasm sources, while 73% of oilseed B-line diversity traced to eight germplasm sources. Seventy-three percent of confectionery R-line diversity traced to two germplasm sources, while 65% of confectionery B-line diversity traced to four germplasm sources. The mean coancestry between oilseed R-lines was 0.25, between oilseed B-lines was 0.10, between confectionery R-lines was 0.31, and between confectionery B-lines was 0.25; thus, the genetic diversity among oilseed B-lines seems to be wider than among lines within other groups. Pedigree analysis created a nearly complete framework of heterotic groups for public germplasm developed in the USA, even though some lines could not be assigned to heterotic groups because of incomplete pedigree data. By combining pedigree and DNA fingerprint data, a more comprehensive picture of heterotic groups should emerge for cultivated sunflower.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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A Dominant Gene Decreases Erucic and Increases Dienoic Acid in the Seed Oils of Meadowfoam Subspecies (1998)

Knapp, Steven J. ; Crane, Jimmie M.

Springer

Crop science 38 (1998), S. 1541-1544

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ISSN: 1435-0653

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Meadowfoam (Limnanthes alba Benth.) seed oil is a source of erucic acid (22:1 Δ13) and novel very long-chain fatty acids. The fatty acid profiles of L. alba subspecies are distinctly different. L. alba ssp. versicolor produces significantly more erucic acid and significantly less dienoic acid (22:2) than L. alba ssp. alba. The L. alba ssp. alba profile is the standard for certain meadowfoam oil markets. Because changes in the profile could affect meadowfoam oil markets, we completed a study to elucidate the genetics of erucic and dienoic acid content differences in the subspecies. The fatty acid contents of F2 and F3 progeny from an L. alba ssp. alba x L. alba ssp. versicolor (P1 x P2) cross were assayed by gas chromatography. P1 produced 81 g kg-1 erucic acid and 297 g kg-1 dienoic acid, whereas P2 produced 242 g kg-1 erucic acid and 86 g kg-1 dienoic acid. There were two non-overlapping erucic by dienoic acid phenotypic classes among 100 F2 progeny. The phenotypic distribution (79:21) was not significantly different from 3:1 (P = 0.48); thus, these progeny segregated for a dominant gene. This was verified by F3 progeny tests. Unless markets can tolerate the range of fatty acid compositions found in L. alba germplasm, cultivars with the L. alba ssp. alba fatty acid profile must be developed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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5

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A Seed Specific δ-12 Oleate Desaturase Gene is Duplicated, Rearranged, and Weakly Expressed in High Oleic Acid Sunflower Lines (1998)

Hongtrakul, Vipa ; Slabaugh, Mary B. ; Knapp, Steven J.

Springer

Crop science 38 (1998), S. 1245-1249

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ISSN: 1435-0653

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Helianthus annuus L.) germplasm typically contains 140 to 350 g kg-1 oleic acid (18:1). Sunflower germplasm with 800 to 950 g kg-1 18:1 (high oleic germplasm) has been developed with a dominant mutation (Ol originating from the cultivar 'Pervenets'. We speculated that this mutation reduced the activity or expression of a δ-12 oleate desaturase (OLD) gene. This was tested by cloning OLD genes expressed in developing seeds and comparing nucleotide sequences, OLD transcript concentrations, and OLD restriction fragment lengths among wild-type (low oleic) and backcross-derived mutant (high oleic) lines fixed for ol or Ol alleles, respectively. An Arabidopsis thaliana L. OLD ( At OLD) cDNA probe was used to isolate a full-length cDNA clone (OLD-7) from a developing seed cDNA library of sunflower, OLD-7 was strongly expressed in developing seeds, but was not expressed in the other tissues sampled. The nucleotide sequences for OLD-7 ORDs from partially isogenic low and high oleic acid lines (HA89 and HA341) were 100% identical. High oleic lines had substantially lower OLD-7 transcript concentrations than low oleic lines. Restriction fragment analyses showed that OLD-7 is duplicated and rearranged in mutant lines and linked to the Ol locus; thus, increased oleic acid content seems to be caused by DNA changes affecting OLD-7 cis regulatory sequences. OLD-7 RFLPs distinguish between Ol locus genotypes and can be used to accelerate the development of high oleic lines in sunflower.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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6

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Donor Inbred Lines for Enhancing the Performance of Single-Cross Sunflower Hybrids (1999)

Cheres, Mercy T. ; Miller, Jerry F. ; Knapp, Steven J.

Springer

Crop science 39 (1999), S. 1325-1331

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ISSN: 1435-0653

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Helianthus annuus L.) have not been systematically screened as a source of new favorable alleles for enhancing hybrid performance. The objective of this study was to assess the merits of a sample of three hybrids (HA383 × RHA373, HA372 × RHA377, and HA89 × RHA373). The net gain of favorable alleles and several other statistics were estimated from the seed yield means of 14 sterility maintainer (B) lines, four fertility restorer (R) lines, 81 B × B hybrids, and 42 B × R hybrids in field tests at Corvallis, OR and Casselton, ND in 1996 and 1997. HA383 × RHA373, HA372 × RHA377, and HA89 × RHA373 were the highest-yielding hybrids from three heterotic patterns. HA383 × RHA373 had the highest seed yield across years and locations (3285 kg ha-1) among all hybrids. The most promising donors for increasing the seed yield of HA383 × RHA373 were HA822, HA851, and HA372. Similarly, the most promising donors for increasing the seed yield of HA372 × RHA377 were HA821 and HA384, and the most promising donors for increasing seed yield of HA89 × RHA373 were HA383, HA384, and HA821. The elite gene pool of sunflower seems to be a rich source of favorable alleles for increasing hybrid seed yields.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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7

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Cuphea wrightii thioesterases have unexpected broad specificities on saturated fatty acids (1997)

Leonard, Jeffrey M. ; Slabaugh, Mary B. ; Knapp, Steven J.

Springer

Plant molecular biology 34 (1997), S. 669-679

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ISSN: 1573-5028

Keywords: Cuphea ; FatB ; fatty acid ; medium-chain ; seed oil ; thioesterase

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Cuphea wrightii A. Gray is an herbaceous annual that accumulates 30% caprate (10:0) and 54% laurate (12:0) in seed storage lipids. We investigated the role of acyl-acyl carrier protein (ACP) thioesterases (TE) in acyl chain-length regulation in C. wrightii. Two embryo-derived cDNAs, encoding the TEs Cw FatB1 and Cw FatB2, were isolated. Both proteins were detected in developing embryos and mature seeds but not in other tissues, suggesting involvement in seed oil synthesis. Although expected to be 10:0/12:0-ACP-specific, these genes produced a broad range of fatty acids (12:0, 14:0, and 16:0) in transgenic Arabidopsis with the greatest accumulation at 14:0. Cw FatB2 transformants also accumulated small amounts of 10:0. Because C. wrightii accumulates only ca. 5% 14:0 and ca. 2% 16:0, we tested the possibility that gene dosage effects might significantly alter the overall kinetics of the pathway. Phenotypic comparisons of progeny segregating for the transgenes individually and in a hybrid population demonstrated that increased enzyme pools in vivo had a minor effect on diverting fatty acid production to shorter chains. We propose that Cw FatB1 and Cw FatB2 may be necessary but not sufficient determinants of the C. wrightii phenotype.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1005846830784

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