High Oleic Genotypes Research Articles

A single point mutation in a member of FAD2 multigene family resulted in the generation of a high oleic line of Silybum marianum (L.) Gaertn.

Silybum marianum (L.) Gaertn. has been recently valorised as oilseed crop for its productivity and for the chemical composition of its oil. However, a high oleic acid oil (HO) line, which would be useful for cooking but also for biodiesel production and other industrial applications, was not found in its natural germplasm. To address this issue, an ethyl methanesulfonate-induced mutagenesis programme was implemented, and the screening of the mutagenized population led to the identification of a HO mutant line with a much higher oleic acid oil content with respect to the wild type (WT). Since Fatty Acid Desaturase 2 (FAD2) genes are responsible for the determination of oleic acid levels in vegetable oils of other species, the present research focused on the characterization of this gene family as the possible target of mutagenesis. An extremely large multigene family consisting of twenty-one unique and complete FAD2 orthologous sequences was identified in S. marianum. Sequence comparison of all the SmFAD2 genes between the WT and HO genotypes revealed a single nucleotide polymorphism (SNP) in SmFAD2–1, the only fruit-specific gene, resulting in a non-synonymous substitution in the predicted protein in the high oleic genotype. The SNP and the HO phenotype were found to perfectly cosegregate in the F2 progeny derived from the HO x WT crosses, suggesting the direct implication of this gene in the determination of oleic and linoleic acid fruit content in S. marianum fruits.

Comparison of Field Emergence and Thermal Gradient Table Germination Rates of Seed from High Oleic and Low Oleic Near Isogenic Peanut Lines

ABSTRACT Oxidative stability is an important factor considered by those in the peanut manufacturing industry. Product stability has been shown to increase up to seven-fold when high-oleic peanuts are used. The percentage of US crop that is high-oleic continues to increase, but many producers are reluctant to grow high-oleic cultivars due to the uncertainty of the high-oleic effect on agronomic traits, such as seed germination, yield and grade. Experiments were designed and conducted to examine the effect of the high oleic trait on peanut seed germination in field plots and in the laboratory on a thermal gradient table. Genotypes used in these experiments included cultivars or breeding lines from each peanut market-type along with their near-isogenic, high oleic counterparts. Field emergence, or germination, was recorded in the field in 4 geographically different regions, as well as in the laboratory on a thermal gradient table. Thermal gradient table experimental results demonstrated a lag in germination in high oleic genotypes compared to their normal oleic counterparts in all market-types, but the effect was lowest in the runner-type pair. Results from these experiments increase the understanding of the agronomic properties of high-oleic peanut cultivars and could influence the modification of standard protocols used by state agencies to test high-oleic peanut germination for registered seed quality labeling. Furthermore, this study indicates that although producers may experience delayed germination from high oleic seed compared to low oleic counterparts, this germination lag is overcome by 21 days post-planting and does not negatively impact the agronomical performance of high oleic cultivars.

Allelism Test between Crosses of High-O/L x High-O/L and Very High-O/L x Very High-O/L Peanut Genotypes

ABSTRACT Crosses were made between High-O/L x High-O/L and between Very High-O/L x Very High-O/L peanut genotypes. The High-O/L parental genotypes were F435-OL-2 and ‘Flavor Runner 458’ and ranged between 20 and 40:1 oleic (O) to linoleic (L) fatty acid methyl ester ratio. The Very High-O/L parental cultivars were ‘Georgia Hi-O/L' and ‘Georgia-11J' and consistently had O/L ratios ≥40:1 over four years at the Tifton, Georgia location when grown under maximum-input production practices with irrigation. F1 plants from the High-O/L x High-O/L cross combination had an average O/L ratio of 32.5:1; whereas, the F1 plants from the Very High-O/L x Very High-O/L crosses had an average O/L ratio of 50:1. Average O/L ratios of both F2 and F3 generation progeny also had similar O/L ratios within High-O/L x High-O/L and Very High-O/L x Very High-O/L crosses. The results from these test crosses suggest that there are at least two different high-oleic genotypes possibly associated with either multiple alleles or modifier genes.

Effects of Genotype and Nitrogen Availability on Grain Yield and Quality in Sunflower

Core Ideas Positive effect of genotype and N on yield and protein in grains and meal. No effect of genotype and N on concentration of oil in grain. High oleic genotypes showed higher protein concentration of grains and by‐products. Nitrogen increased the protein /oil ratio of the grains. Nitrogen improved the quality of sunflower by‐products. Sunflower (Helianthus annuus L.) conventional (CONV) and high oleic (HO) genotypes differ in yield and quality. Nitrogen affects grain yield, quality, and by‐products protein concentration. The objective was to evaluate the effect of genotype and N on grain yield, oil (OG) and protein (PG) concentration in grain and in by‐products (PM). The effect of genotype was evaluated in Exp. 1 with 7 CONV and 7 HO hybrids, at two planting dates (PD early and late). The effect of N (Exp. 2) was evaluated in 10 locations (3 with CONV and 7 with HO), under six N rates (0, 30, 60, 90, 120, and 150 kg N ha−1). We determined yield, OG, PG and PM. For the early PD of E1, yield was higher in HO than CONV genotypes (3822 kg ha−1 vs. 3495 kg ha−1). In Exp. 2, N increased yield in 50% of the locations (HO: 586; CONV: 597 kg ha−1). In Exp. 1, genotype did not affect OG, but PG was higher in HO than in CONV ones (18.0 vs. 16.8%, respectively). In Exp. 2, N did not affect OG, but increased PG in both types of genotypes. Consequently, PG/OG ratio increased with N rates. The higher PG, was also reflected in higher PM (44.0% HO and 38.8% CONV, respectively). Increases of 2.5% points in PG resulted in increases of 5.6 in PM. Therefore, the application of N would allow obtaining high yields and PG without detrimental effects on OG, improving the quality of grains and by‐products.

Oleic acid variation and marker-assisted detection of Pervenets mutation in high- and low-oleic sunflower cross

High-oleic sunflower oil is in high demand on the market due to its heart-healthy properties and richness in monounsaturated fatty acids that makes it more stable in processing than standard sunflower oil. Consequently, one of sunflower breeder’s tasks is to develop stable high-oleic sunflower genotypes that will produce high quality oil. We analyzed variability and inheritance of oleic acid content (OAC) in sunflower, developed at the Institute of Field and Vegetable Crops, by analyzing F1 and F2 progeny obtained by crossing a standard linoleic and high-oleic inbred line. F2 individuals were classified in two groups: low-oleic with OAC of 15.24-31.28% and high-oleic with OAC of 62.49-93.82%. Monogenic dominant inheritance was observed. Additionally, several molecular markers were tested for the use in marker-assisted selection in order to shorten the period of detecting high-oleic genotypes. Marker F4-R1 was proven to be the most efficient in detection of genotypes with Pervenets (high-oleic acid) mutation.

High yielding-high oleic non-genetically modified Indian safflower cultivars

High oleic safflower (Carthamus tinctorius L.) oil is desired by industry because of its high oxidative stability for broader use in food, fuel, and other products. However, standard safflower oil has only 16–20% oleic acid, and Indian safflower cultivars are non-oleic type. The present investigation was taken up to enhance oleic acid level in Indian safflower. Three non-genetically modified high-oleic lines, ISF-1, ISF-2 and ISF-3 were developed from a cross between low and high oleic genotypes through classical breeding approach. These were tested at 10 locations in India along with two non-oleic high yielding check varieties, A1 and Nari-6 under irrigated and dry growing conditions. ISF-1, ISF-2 and ISF-3 consistently possessed high oleic acid content across locations. The mean oleic acid content in these varieties was 75, 76 and 75%, respectively whereas it was 17 and 14% in non-oleic checks. Oleic acid level in ISF-1, ISF-2 and ISF-3 was relatively low under dry growing conditions (72, 73, 73%) than under irrigated (77, 78, 76%). On an average ISF-1 and ISF-2 gave 15 and 9% higher seed yield and 23 and 27% higher oil yield, respectively than the best check, A1. Oleic acid content was not affected when tested at three dates of sowing with one month interval; however, considerable reduction in seed yield was observed as sowing was delayed. ISF-1 and ISF-2 were licensed to Marico Pvt. Ltd., Mumbai, India for large scale production. These are the first oleic safflower cultivars developed for growing under Indian conditions.

Environmental effect on sunflower oil quality

Sunflower is one of the most important oilseed crops and produces a high-quality edible oil. Balance of fatty acids in standard sunflower oil shows preponderance of linoleic rather than oleic acid, and conditions during seed development, such as temperature, changes the oleic/linoleic ratio of the oil. This work aimed to evaluate the environmental effect on fatty acid profile in a group of standard and high oleic varieties and hybrids. Seeds were produced during regular season crop and during off-season crop featuring different temperatures from anthesis to maturity. Fatty-acid composition was determined by gas chromatography. Levels of oleic acid, in standard oil genotypes, raised as the crop developed in warmer environment while levels of linoleic acid decreased, and the opposite was observed when the crop was grown under lower temperature. High oleic genotypes were less sensitive to environment switching and showed lower variation on fatty-acid composition.

RNAi-mediated down-regulation of the expression of OsFAD2-1: effect on lipid accumulation and expression of lipid biosynthetic genes in the rice grain.

BackgroundThe bran from polished rice grains can be used to produce rice bran oil (RBO). High oleic (HO) RBO has been generated previously through RNAi down-regulation of OsFAD2-1. HO-RBO has higher oxidative stability and could be directly used in the food industry without hydrogenation, and is hence free of trans fatty acids. However, relative to a classic oilseed, lipid metabolism in the rice grain is poorly studied and the genetic alteration in the novel HO genotype remains unexplored.ResultsHere, we have undertaken further analysis of role of OsFAD2-1 in the developing rice grain. The use of Illumina-based NGS transcriptomics analysis of developing rice grain reveals that knockdown of Os-FAD2-1 gene expression was accompanied by the down regulation of the expression of a number of key genes in the lipid biosynthesis pathway in the HO rice line. A slightly higher level of oil accumulation was also observed in the HO-RBO.ConclusionProminent among the down regulated genes were those that coded for FatA, LACS, SAD2, SAD5, caleosin and steroleosin. It may be possible to further increase the oleic acid content in rice oil by altering the expression of the lipid biosynthetic genes that are affected in the HO line.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0881-6) contains supplementary material, which is available to authorized users.

Fatty acid composition of high oleic sunflower hybrids in a changing environment

High oleic hybrids of sunflower are widely cultivated around the world. The effect of temperature on oleic acid percentage of these hybrids is a concern, since oils with oleic acid percentage above a threshold receive a prime over the regular price. The objective of this work was to identify the main avenues for the genetic improvement of oleic acid percentage of high oleic hybrids of sunflower, both in current and future global warming scenarios. A data set obtained in a trial network allowed to explore the oleic acid percentage response to temperature of high oleic hybrids in the argentine sunflower growing region (between 29 and 38° LS, 46 trials in 15 locations during the period 2005/06–2012/2013). A similar data set was used to evaluate the variability in phenology. Mean values and stability across environments of oleic acid percentage differed among the studied high oleic hybrids. Differences in the parameter values of a sigmoid equation evidenced the variability in the response of oleic acid to temperature. Oleic acid percentage was simulated with a model that included this equation coupled to a phenology module, for different sowing dates and locations with contrasting temperature, under current conditions and a global warming scenario. It was possible to identify a low number of temperatures and field environments useful to reproduce the rankings of hybrids obtained with a wide range of temperatures. This information could be used to phenotype for high oleic percentage with a low number of experiments and reduce the efforts to identify better high oleic genotypes. Simulations show that the maximum oleic acid percentage is currently not attained in 50% of the studied hybrids in some sowing dates, even at the warmest locations, while in a future global warming scenario it would not be attained in 30% of the studied hybrids in the colder locations. Sensitivity analysis was performed for parameters of the sigmoid equation and the phenology module determining when the critical period for fatty acid composition occurs. In both in current and future scenarios, phenology parameters showed a null or low effect on oleic acid percentage. Two parameters of the sigmoid equation showed a significant impact, which differed between current and future scenarios. Simulations suggest that the stability of oleic acid percentage could still be a concern in the future. However, selecting for key parameter values for a given scenario could help to obtain better high oleic hybrids of sunflower.

Oxidative stability of sunflower oil methyl biodiesel of the conventional and high oleic genotypes

Os óleos e seus produtos derivados são susceptíveis a oxidação, devido aos ácidos graxos insaturados presente em sua composição. O óleo e o biodiesel obtidos de oleaginosas apresentam valores baixos de estabilidade oxidativa, variando com o percentual de ácidos graxos insaturados. O presente trabalho visa o estudo da estabilidade oxidativa e caracterização do biodiesel obtido a partir de óleo de girassol com diferentes graus de insaturação. Foram selecionados três genótipos para extração mecânica do óleo, sendo dois do tipo convencional e um do tipo alto oleico. Posteriormente, o óleo vegetal foi submetido à reação de transesterificação via rota metílica utilizando-se de catálise homogênea. O biodiesel foi caracterizado para massa específica, teor de umidade, índice de acidez, índice de iodo, estabilidade oxidativa e teor de ésteres. Os biodieseis das variedades de óleos de girassol convencional apresentaram como características baixos valores de estabilidade oxidativa, porém o biodiesel derivado do óleo tipo alto oleico SYN 3950 apresentou maior estabilidade oxidativa e menores valores de índice de iodo indicando menor teor de insaturações. As análises cromatográficas do biodiesel do óleo alto oleico comprovaram os resultados obtidos, sugerindo que este resistirá a um período mais longo à oxidação.

Germination responses to temperature and water potential as affected by seed oil composition in sunflower

Sunflower genotypes with increased concentration of stearic and oleic acids have been developed to fulfil industrial specific requirements. Fatty acid composition of membranes has been widely described to affect seed germination, but the effect of composition of reserve lipids on germination is still unknown. Two experiments were conducted including: traditional (high linoleic), high stearic–high oleic, high stearic–high linoleic and high oleic genotypes. Thermal and hydrotime analyses were performed on germination data obtained from the incubation of seeds at different temperatures and water potentials. Fatty acid composition affected the parameters values of thermal time model. Base temperature was inversely related to linoleic acid concentration. Genotypes with high linoleic acid concentration germinated earlier at low temperatures, while no significant differences among genotypes at temperatures above 15°C were found. High stearic–high oleic genotypes showed lower thermal time requirement for 50% germination than traditional and high stearic–high linoleic genotypes. The parameters of hydrotime model were not affected by fatty acid composition, but at low water potentials and high temperatures thermo-dormancy was induced and strongly reduced final seed germination in all genotypes studied. In conclusion, breeding for higher oleic acid and lower linoleic acid concentration in sunflower oil may affect seed germination performance at low temperatures.

Nonsense-mediated mRNA degradation of CtFAD2-1 and development of a perfect molecular marker for olol mutation in high oleic safflower (Carthamus tinctorius L.)

There are two types of safflower oil, high oleic (HO) with 70-75% oleic acid and high linoleic (HL) with about 70% linoleic acid. The original HO trait in safflower, found in an introduction from India, is controlled by a partially recessive allele ol at a single locus (Knowles and Bill 1964). In the lipid biosynthesis pathway of developing safflower seeds, microsomal oleoyl phosphatidylcholine desaturase (FAD2) is largely responsible for the conversion of oleic acid to linoleic acid. In vitro microsomal assays indicated drastically reduced FAD2 enzyme activity in the HO genotype compared to conventional HL safflower. A previous study indicated that a single-nucleotide deletion was found in the coding region of CtFAD2-1 that causes premature termination of translation in the HO genotypes, and the expression of the mutant CtFAD2-1Δ was attenuated in the HO genotypes compared to conventional HL safflower (Guan et al. 2012). In this study, we hypothesise that down-regulation of CtFAD2-1 expression in the HO genotype may be explained by nonsense-mediated RNA decay (NMD). NMD phenomenon, indicated by gene-specific RNA degradation of defective CtFAD2-1Δ, was subsequently confirmed in Arabidopsis thaliana seed as well as in the transient expression system in Nicotiana benthamiana leaves. We have developed a perfect molecular marker corresponding to the olol mutation that can facilitate a rapid screening and early detection of genotypes carrying the olol mutation for use in marker-assisted selection for the management of the HO trait in safflower breeding programmes.

Stability of seed oil quality traits in high and mid-oleic acid sunflower hybrids

Seed oil content and composition are important considerations in sunflower breeding programmes because these traits are related to oil quality. They are complex traits that are determined by genotypic factors and environmental conditions. The objective of this study was to estimate the interaction between genotype and environment for oil content and major fatty contents in traditional, high and mid-oleic sunflower genotypes and to identify stable genotypes. Combined analyses of variance of oil, oleic and linoleic acid content of 16 genotypes tested over six locations showed highly significant mean squares for genotype, environment and the interaction between them. On average the mid-oleic and standard genotypes had similar oil contents, but the high oleic genotypes had lower oil contents than the standard genotypes. Stability analyses indicated that one standard, one high oleic and one mid-oleic genotype were relatively stable with average to above average oil content. One high oleic genotype was stable across locations with an oleic acid content of above 80 %. The unstable high oleic acid genotypes that showed variation for oleic acid content across locations may be a consequence of location, temperature and rainfall effects. With adequate location and planting dates, high and mid-oleic hybrids could be produced with oil that meets the oil quality standards.

Influence of Temperature on the Fatty Acid Composition of the Oil From Sunflower Genotypes Grown in Tropical Regions

AbstractThe influence of temperature on the fatty acid composition of the oils from conventional and high oleic sunflower genotypes grown in tropical regions was evaluated under various environmental conditions in Brazil (from 0° S to 23° S). The amounts of the oleic, linoleic, palmitic and stearic fatty acids from the sunflower oil were determined using gas chromatography (GC). The environment exhibited little influence on the amounts of oleic and linoleic fatty acids in high oleic genotypes of sunflower. In conventional genotypes, there was broad variation in the average amounts of these two fatty acids, mainly as a function of the minimum temperature. Depending on the temperature, especially during the maturation of the seeds, the amount of oleic acid in the oil of conventional sunflower genotypes could exceed 70 %. Higher temperatures led to average increases of up to 35 % for this fatty acid. Although the minimum temperature had the strongest effect on the fatty acid composition, locations at the same latitude with different minimum temperatures displayed similar values for both oleic acid and linoleic acid. Furthermore, minimum temperature had little influence on the amounts of palmitic and stearic fatty acids in the oil.

Types of gene effects governing the inheritance of oleic and linoleic acids in peanut (Arachis hypogaea L.)

Oleic and linoleic acids are major fatty acids in peanut determining the quality and shelf-life of peanut products. A better understanding on the inheritance of these characters is an important for high-oleic breeding programs. The objective of this research was to determine the gene actions for oleic acid, linoleic acid, the ratio of oleic to linoleic acids (O/L ratio) and percentage oil (% oil) in peanut. Georgia-02C, SunOleic 97R (high-oleic genotypes) and KKU 1 (low-oleic genotypes) were used as parents to generate P 1 , P 2 , F 2 , F 3 , BC 11 S and BC 12 S. The entries were planted in a randomized complete block design with four replications in the rainy season (2008) and the dry season (2008/2009). Gas liquid chromatography (GLC) was used to analyze fatty acid compositions. The data were used in generation means analysis to understand gene effects. The differences in season, generation and generation X season interactions were significant for oleic acid in the crosses Georgia-02C X KKU 1 and SunOleic 97R X KKU 1. Additive, dominance and epistasis gene effects were significant for oleic acid, linoleic acid, O/L ratio and % oil. Initial selection can be carried out in early segregating population, and final selection in late generations. Keywords: Breeding, gene actions, generation mean analysis, groundnut, oil quality

Environmental Stability of Oleic Acid Concentration in Seed Oil for Soybean Lines with FAD2‐1A and FAD2‐1B Mutant Genes

ABSTRACTElevating oleic acid in seed oil improves oxidative stability and is desirable for expanding edible and industrial uses of soybean [Glycine max (L.) Merr.]. Soybean lines with up to 800 g kg−1 oleic acid concentration were developed by combining a recessive mutant allele at the FAD2‐1A locus (Glyma10 g42470) with either of two different recessive mutant alleles at the FAD2‐1B locus (Glyma20 g24530). However, oleic acid concentration for some higher oleic acid genotypes can be affected by growing conditions. The objective of this study was to evaluate the stability of oleic acid concentration among 10 soybean lines with elevated oleic acid and eight checks with typical oleic acid levels over six environments. High oleic genotypes with genes combined from crossing M23 with the FAD2‐1AΔ mutant and PI567189A with the FAD2‐1B mutant I143T accumulated less oleic acid, and means for oleic acid concentration ranged from 551 to 729 g kg−1 across environments compared to 202 to 263 g kg−1 in the check cultivars. Significant variation among environments indicated that genes from different sources can affect both concentration and stability of oleic acid of these soybean genotypes grown in different environments.

A Study of the Relationships among Consumer Acceptance, Oxidation Chemical Indicators, and Sensory Attributes in High‐Oleic and Normal Peanuts

The purpose of this study was to determine the relationships between overall acceptance, chemical indicators, and sensory attributes in roasted peanuts harvested from high-oleic peanut genotypes produced in Argentina. Oleic/linoleic ratio (O/L), peroxide value, p-anisidine value, conjugated dienes, consumer acceptance, and descriptive analysis were performed on roasted peanuts prepared using 16 genotypes of normal and high-oleic peanuts. Principal component and cluster analysis were performed on the chemical and sensory data from peanut genotypes. Acceptance was positively associated with O/L, crunchiness, sweetness, roasted peanutty flavor, and hardness. Acceptability was negatively associated with cardboard, oxidized, and sour flavors. The high-oleic genotypes, 4896-11-C, and 9399-10 showed high consumer acceptance with 7 or "like moderately" in a hedonic scale of 9 points. Some high-oleic peanut lines, such as 9399-10, could be used to replace normal peanuts without affecting consumer acceptance of peanut products processed from them and more stability due to the high-oleic condition.

An insertion of oleate desaturase homologous sequence silences via siRNA the functional gene leading to high oleic acid content in sunflower seed oil

Classical sunflower varieties display a high linoleic acid content in their seeds [low oleic (LO) varieties] whereas genotypes carrying the Pervenets mutation display an increased oleic acid content of above 83% [high oleic (HO) varieties]. Despite the advantage in health terms of oleic acid, the nature of the mutation was still unknown. Previous work reported that HO genotypes carried a specific oleate desaturase (OD) allele. This enzyme catalyses the desaturation of oleic acid into linoleic acid. The present work demonstrates that this allele is organised in two parts: the first section present in both HO and LO genotypes carries a normal OD gene, the second section is specific to HO genotypes and carries OD duplications. The study of mRNA accumulation in LO and HO seeds revealed that the mutation is dominant and induces an OD mRNA down-regulation. Furthermore, OD small interfering RNA, characteristic of gene silencing, accumulated specifically in HO seeds. Considered together, these observations show that the mutation is associated with OD duplications leading to gene silencing of the OD gene and consequently, to oleic acid accumulation. This finding allowed the development of molecular markers characterising the mutation that can be used in breeding programmes to facilitate the selection of HO genotypes.

Up-to-date results on biochemical genetics of sunflower in vniimk

Forty-seven specimens from the world germplasm collection of VIR were crossed as male with a high oleic line HA89A OL as female. The mean of 10 seed samples of F1 was 83% oleic acid content. High oleic trait was mainly dominant. Two crosses showed intermediate inheritance with the means of 62% and 68%. The range of single-seed variability of these two crosses was from 53% to 89% oleic acid. The genotypes showing abnormal segregation in F1 have been selected to develop a set of normal lines with a suppressor for Ol mutation. The inheritance of mid- (increased) oleic content (about 62%) was studied in the F1, F2 and BC generations of the inbred line LG27 crossed with the high oleic line HA89 OL. Mid-oleic acid content was shown to be controlled by a recessive allele of ol gene, designated ol1. An inbred line with 92% oleic content was obtained to investigate a super high oleic genotype. Another high oleic line was selected for low stearic content, about 1%. High palmitic (about 24%) line is being developed. High-oleic mutation is quite detectable both in immature and germinated seeds. Mutations for tocopherol composition, tph1 and tph2, have a high level of expressivity in different parts of the plant. It was shown for tph2 mutation that its heterozygotes could be clearly identified by the analysis of pollen from a single head. The open pollinated variety Favorite was developed in VNIIMK in 1993. It was shown that seed oil of the variety had about three times higher hydrolytic stability estimated as the lower level of free fatty acid value of crude oil.

High-stearic and High-oleic cottonseed oils produced by hairpin RNA-mediated post-transcriptional gene silencing.

We have genetically modified the fatty acid composition of cottonseed oil using the recently developed technique of hairpin RNA-mediated gene silencing to down-regulate the seed expression of two key fatty acid desaturase genes, ghSAD-1-encoding stearoyl-acyl-carrier protein Delta 9-desaturase and ghFAD2-1-encoding oleoyl-phosphatidylcholine omega 6-desaturase. Hairpin RNA-encoding gene constructs (HP) targeted against either ghSAD-1 or ghFAD2-1 were transformed into cotton (Gossypium hirsutum cv Coker 315). The resulting down-regulation of the ghSAD-1 gene substantially increased stearic acid from the normal levels of 2% to 3% up to as high as 40%, and silencing of the ghFAD2-1 gene resulted in greatly elevated oleic acid content, up to 77% compared with about 15% in seeds of untransformed plants. In addition, palmitic acid was significantly lowered in both high-stearic and high-oleic lines. Similar fatty acid composition phenotypes were also achieved by transformation with conventional antisense constructs targeted against the same genes, but at much lower frequencies than were achieved with the HP constructs. By intercrossing the high-stearic and high-oleic genotypes, it was possible to simultaneously down-regulate both ghSAD-1 and ghFAD2-1 to the same degree as observed in the individually silenced parental lines, demonstrating for the first time, to our knowledge, that duplex RNA-induced posttranslational gene silencing in independent genes can be stacked without any diminution in the degree of silencing. The silencing of ghSAD-1 and/or ghFAD2-1 to various degrees enables the development of cottonseed oils having novel combinations of palmitic, stearic, oleic, and linoleic contents that can be used in margarines and deep frying without hydrogenation and also potentially in high-value confectionery applications.