J. F. Miller

Screening for low grain cadmium phenotypes in sunflower, durum wheat and flax

Cadmium (Cd) level in nonoilseed sunflower (Helianthus annuus L.), flax (Linum usitatissimum L.), and durum wheat (Triticum turgidum L. var. durum) grown on uncontaminated, alkaline soils has exceeded limits established in Northern Europe. Separate field experiments were conducted to investigate variability of grain Cd levels among sunflower, durum wheat and flax germplasm, and to seek an efficient screening method for future breeding. There were large variations in leaf Cd concentration among 200 sunflower lines. These lines performed more consistently for Cd uptake at the R5 stage than at the V8 stage across 4 locations with markedly differing soils. Cd concentration in V8 leaves was not related to Cd in grain. The positive correlation between R5 leaf Cd and kernel Cd level was obtained from nonoilseed hybrid (Sigco 954) (R2; = 0.74**), and 200 lines (R2 = 0.44**) tested over 4 locations in 2 field trials, respectively. This indicates that an efficient and low cost screening method can be developed for genotype selection, but plants must be grown to the R5 stage. A preliminary evaluation of 30 durum wheat and 74 flax lines indicated large variations in grain Cd level of durum wheat and flax. Grain Cd concentration ranged from 0.11 to 0.34 mg Cd kg-1 DW for durum wheat, and 0.14 to 1.37 mg Cd kg-1 DW for flax, respectively. This variability indicates that breeding for low grain Cd in durum wheat and flax should be feasible.

Acetohydroxyacid synthase mutations conferring resistance to imidazolinone or sulfonylurea herbicides in sunflower

Wild biotypes of cultivated sunflower (Helianthus annuus L.) are weeds in corn (Zea mays L.), soybean (Glycine max L.), and other crops in North America, and are commonly controlled by applying acetohydroxyacid synthase (AHAS)-inhibiting herbicides. Biotypes resistant to two classes of AHAS-inhibiting herbicides—imidazolinones (IMIs) or sulfonylureas (SUs)—have been discovered in wild sunflower populations (ANN-PUR and ANN-KAN) treated with imazethapyr or chlorsulfuron, respectively. The goals of the present study were to isolate AHAS genes from sunflower, identify mutations in AHAS genes conferring herbicide resistance in ANN-PUR and ANN-KAN, and develop tools for marker-assisted selection (MAS) of herbicide resistance genes in sunflower. Three AHAS genes (AHAS1, AHAS2, and AHAS3) were identified, cloned, and sequenced from herbicide-resistant (mutant) and -susceptible (wild type) genotypes. We identified 48 single-nucleotide polymorphisms (SNPs) in AHAS1, a single six-base pair insertion-deletion in AHAS2, and a single SNP in AHAS3. No DNA polymorphisms were found in AHAS2 among elite inbred lines. AHAS1 from imazethapyr-resistant inbreds harbored a C-to-T mutation in codon 205 (Arabidopsis thaliana codon nomenclature), conferring resistance to IMI herbicides, whereas AHAS1 from chlorsulfuron-resistant inbreds harbored a C-to-T mutation in codon 197, conferring resistance to SU herbicides. SNP and single-strand conformational polymorphism markers for AHAS1, AHAS2, and AHAS3 were developed and genetically mapped. AHAS1, AHAS2, and AHAS3 mapped to linkage groups 2 (AHAS3), 6 (AHAS2), and 9 (AHAS1). The C/T SNP in codon 205 of AHAS1 cosegregated with a partially dominant gene for resistance to IMI herbicides in two mutant × wild-type populations. The molecular breeding tools described herein create the basis for rapidly identifying new mutations in AHAS and performing MAS for herbicide resistance genes in sunflower.

Genetic distance as a predictor of heterosis and hybrid performance within and between heterotic groups in sunflower

Abstract Heterosis is significant for seed yield and is one of the driving forces behind the hybrid seed industry in cultivated sunflower (Helianthus annuus L). Heterotic groups in sunflower, if any other than the female and male inbred-line groups exist, have not been well studied or described. The primary aims of this study were to assess the utility and validity of a series of proposed heterotic groups and estimate correlations between genetic distance, heterosis, and hybrid performance for seed yield in sunflower. Fortytwo female by male heterotic group (A × R) and 81 female by female heterotic group (A × B) single-cross hybrids were grown in Corvallis, Ore., and Casselton, N.D., in 1996 and 1997. Heterosis was significant for seed yield and plant height but not for seed oil concentration and days to flowering. Genetic distances were significantly correlated with hybrid seed yield when estimated from AFLP fingerprints (GD) (r = 0.63 for A × R and 0.79 for A × B hybrids), but not from coancestries (GC) (r = -0.02 for A × R and 0.54 for A × B hybrids). GD (R2 = 0.4) was a poor predictor of hybrid seed yield. The proposed heterotic groups in sunflower seem to have utility, but do not seem to be as strongly differentiated as those in corn (Zea mays L.). The highest-yielding hybrids were from the BC× RB heterotic pattern; however, several BC× BC hybrids (within-group hybrids) were among the top-yielding hybrids. The outstanding performance of certain BC× BC hybrids casts some doubt on the validity of the BC group. Substantial genetic diversity seems to be present within and between heterotic groups in sunflower.

Altering Fatty Acid Composition in Oil Seed Crops

World consumption of vegetable oils increased steadily in the last decade, from 62.6 million metric tons (MMT) in 1993 to 87.8 MMT in 2000 (Goblitz, 2002). This demand has been primarily due to increased use of edible oils in food preparation. Yet, vegetable oils are being used in many industrial products including fuels. Part of this has resulted from alteration of the fatty acid composition of vegetables oils making them more versatile in their uses. The four major oilseed crops are soybean (Glycine max L. Merr.), sunflower (Helianthus annuus L.), rapeseed (Brassica), and peanut (Arachis hypogaea L.). The seed oil of these has been genetically altered through standard plant breeding methodology and molecular genetic engineering. The following is a review of recent developments in the genetic manipulation of these crop plants to change seed oil quality.

Inheritance of reduced height in sunflower

SummaryBreeding to improve stem strength is a major objective of researchers of sunflower (Helianthus annuus L.). This study was undertaken to investigate genetic factors controlling reduced plant height and increased stem diameter in three sources of sunflower, DDR, Donsky, and Donskoi 47, crossed with a conventional height line, HA 89. As these two characters may lead to improved standability, knowledge of their inheritance will assist researchers in utilizing proper breeding methods. Estimates of additive, dominance, and epistatic genetic effects controlling reduced height indicated that the additive component was most important in two of the three crosses with the additive and epistatic component nearly equal in the third cross. Breeding efforts to reduce height of sunflower hybrids utilizing these lines in crosses could be effective due to the magnitude of additive effects. The dominance component of genetic effects controlling stem diameter was the most important for two crosses, with both dominance and additive components important for the third cross. Epistasis was present, but minor, for controlling stem diameter. The high relative importance of the dominance component indicates that testcross evaluation of lines in early generations could identify lines for producing increased stem diameter in hybrids. Even though the three sources of sunflower with reduced height were different in morphologic and agronomic characteristics, they had similar genetic control of plant height and stem diameter. Each could be utilized in a breeding program to develop lines with reduced height and larger stem diameter.

Inheritance of reduced saturated fatty acid content in sunflower oil

SUMMARY In recent years, consumers have become concerned with reducing the saturated fat content of their diet. Studies have indicated that high levels of saturated fat consumption are correlated with increased risk of coronary heart disease. The total saturated fat content of oil from current sunflower hybrids averages about 130 g kg-1. To identify sunflower germplasm with reduced saturated fatty acid composition, a total of 884 cultivated sunflower accessions from the USDA-ARS North Central Regional Plant Introduction Station, Ames, Iowa, were screened for fatty acid composition by gas chromatography. PI 250542, a cultivar collected in Egypt by Paul Knowles and deposited into the National Plant Germplasm System in 1958, was identified as an accession with reduced saturated fatty acid content. The fatty acid composition of 26 halfseeds of PI 250542 was determined, and the seeds with lowest saturated fatty acids were grown in the greenhouse. Pollen from a single plant was used to pollinate NMS HA 89, and the F1 seed was grown in the field and self-pollinated. After three generations of selection by half-seed analysis, two lines with a low saturated fatty acid trait were selected. Line RS1 has a striped black and dark gray achene, whereas line RS2 has a light gray achene which often bleaches to white when grown in the field. The total saturated fatty acid composition of RS1 including C16 to C24 fatty acids was 77 g kg-1, and for RS2 was 76 g kg-1 when grown at Fargo, North Dakota, in 2000. To determine inheritance of the reduced saturated fatty acid trait, RS1 and RS2 were pollinated by HA 821, a high saturated fatty acid line, and grown in the greenhouse. The resulting F1 seeds were slightly higher in saturated fatty acids than the RS1 or RS2 parents, but far lower than the HA 821 parent, suggesting that the reduced saturated fatty acid trait was partially dominant. RESUMEN En los años recientes, los consumidores comenzaron cuidar de la reduccion del conteniido de acidos grasos saturados en su alimentacion. Las investigaciones indicaban que el consumo de altas dosis de grasas saturadas es ligado con el riesgo agrandado de aparicion de enfermedades del corazon. El contenido total de grasas saturadas en el aceite de hibridos del girasol, que por el momento predominan en la produccion, es de 130 g kg-1. Para identificar el germplasma del girasol, que posee el contenido reducido de acidos grasos saturados, 884 muestras del girasol de USDA-ARS e la Estacion Regional para la introduccion de plantas, Ames, Iova, fueron investigadas con respecto al contenido de acidos grasos por medio de la hematografia de gas. Para PI 250542, la muestra que Paul Knowles llevo en 1958 de Egipto y depuso en el Sistema Nacional para el germplasma vegetal, se ha constatado que posee el contenido reducido de acidos grasos saturados. El contenido de acidos grasos en la muestra PI 250542 fue constatado en 26 mitades de semillas, y esas con el minimo contenido de acidos grasos saturados fueron plantadas en el invernaculo. El polen de una planta era utilizado para la polinizacion de la linea NMS HA 89, y las plantas de la generacion F1 eran cultivadas en el campo y autopolinizadas. Despues de tres generaciones de seleccion con la utilizacion del analisis de mitades de semillas, han sido formadas dos lineas que poseian la caracteristica del contenido reducido de acidos grasos saturados. La linea RS1 tiene los aquenios negros-gris oscuros, mientras la linea RS2 tiene los aquenios gris claros que muchas veces palidecen al color blanco durante el cultivo en el campo. El contenido total de acidos grasos saturados en la linea RS1, inclusive la gama de acidos grasos de C16 a C24, era de 77 g kg-1, y en la linea RS2 76 g kg-1, en las condiciones del cultivo en Fargo, North Dacota, durante 2000. Para determinar la herencia de la propiedad del contenido reducido de acidos grasos saturados, las lineas RS1 y RS2 han sido polinizadas con el polen de la linea HA 821, que posee el alto contenido de acidos grasos saturados, y pues cultivadas en el invernaculo. Las semillas F1 asi obtenidas tenian un poco mas alto contenido de acidos grasos saturados que los padres RS1 y RS2, pero tambien mucho mas bajo contenido que los padres HA 821, lo que indica que la propiedad del bajo contenido de acidos grasos saturados se hereda como parcialmente predominante. RÉSUMÉ Ces dernières années, les consommateurs ont commencé à souhaiter une diminution des acides gras saturés dans leur alimentation. Des recherches ont démontré que la consommation de doses élevées de gras saturés était liée à une augmentation du risque de maladies cardiaques. Le contenu total des gras saturés dans l’huile des hybrides de tournesol qui domine actuellement le marché est d’environ 130 g kg-1. Dans le but d’identifier le germeplasme du tournesol ayant un contenu réduit d’acides gras saturés, la composition en acides gras saturés d’un total de 884 échantillons de tournesol de culture de la station régionale du centre nord pour l’introduction des plantes USDA-ARS, Ames, Iowa a été examiné par chromatographie en atmosphère gazeuse. On a constaté que le cultivar PI 250542 apporté d’Égypte en 1958 et déposé au Système national pour le germeplasme végétal par Paul Knowles possédait un contenu réduit d’acides gras saturés. La composition en acides gras de 26 demigraines de l’échantillon PI 250542 a été déterminée et les graines qui contenaient le moins d’acides gras saturés ont été semées en serre. Le pollen d’une plante a servi à la pollinisation d’une ligne NMS HA 89, et les plantes F1 ont été cultivées dans un champ et autofécondées. Après trois générations de sélection par analyse de demi-graines, deux lignes possédant comme caractéristique un contenu réduit en acides gras saturés ont été créées. La ligne RS1 a des akènes à rayures grises et blanches et la ligne RS 2, des akènes gris clair qui pâlissent souvent jusqu’à devenir blancs quand elle est cultivée dans les champs. Le contenu total d’acides gras saturés de la ligne RS1, incluant des acides gras de C16 à C24 était de 77 g kg-1 et celui de la ligne RS2, 76 g kg-1 dans les conditions de culture de Fargo, Dakota du Nord en l’an 2000. Pour que soit déterminée la transmission du trait de contenu réduit en acides gras saturés, les lignes RS1 et RS2 ont été pollinisées par la ligne HA 821 qui possède un haut contenu d’acides gras saturés pour être ensuite cultivées en serre. Le contenu en acides gras saturés a été légèrement plus élevé dans les graines F1 que dans celles des parents RS1 et RS2, mais beaucoup plus bas que dans le parent HA821, ce qui suggère que le trait de contenu réduit en acides gras saturés était partiellement dominant.

Diversity among sources of cytoplasmic male sterility in sunflower (Helianthus annuus L.)

SummaryTen cytoplasmic male sterile (CMS) sunflower (Helianthus annuus L.) lines were crossed with nine maintainer or male fertility restorer lines in a diallel crossing scheme. Based on fertility restoration of the F1 generation, CMS lines were divided into four groups. At least two new sources of CMS, CMS PET2 and CMS GIG1, were found to be potentially useful for commercial production of hybrids. Environment had an influence on fertility restoration of one CMS line, CMS MAX1. Effective restoration of male fertility for CMS RIG1, CMS ANN2, and CMS ANN3 was not found.

A new cytoplasmic male sterility source from wild Helianthus annuus

SummaryA new cms source, ANN-5, was found in wild Helianthus annuus. This source showed high stability under different conditions in 1991 and 1992. All progenies from crosses of this source with several stable B-lines and restorer lines, which are homozygous for the gene which restores Leclercqs source of male sterility, were completely male sterile. Flower contained pistils and atrophied stamens. The cytological analysis showed that pollen mother cell degeneration took place in a premeiotic stage.