Assessment of Oil Content and Fatty Acid Composition Variability in Two Economically Important <i>Hibiscus</i> Species

The <i>Hibiscus</i> genus encompasses more than 300 species, but kenaf (<i>Hibiscus cannabinus</i> L.) and roselle (<i>Hibiscus sabdariffa</i> L.) are the two most economically important species within the genus. Seeds from these two <i>Hibiscus</i> species contain a relatively high amount of oil with two unusual fatty acids: dihydrosterculic and vernolic acids. The fatty acid composition in the oil can directly affect oil quality and its utilization. However, the variability in oil content and fatty acid composition for these two species is unclear. For these two species, 329 available accessions were acquired from the USDA germplasm collection. Their oil content and fatty acid composition were determined by nuclear magnetic resonance (NMR) and gas chromatography (GC), respectively. Using NMR and GC analyses, we found that <i>Hibiscus</i> seeds on average contained 18% oil and seed oil was composed of six major fatty acids (each >1%) and seven minor fatty acids (each <1%). <i>Hibiscus cannabinus</i> seeds contained significantly higher amounts of oil (18.14%), palmitic (20.75%), oleic (28.91%), vernolic acids (VA, 4.16%), and significantly lower amounts of stearic (3.96%), linoleic (39.49%), and dihydrosterculic acids (DHSA, 1.08%) than <i>H. sabdariffa</i> seeds (17.35%, 18.52%, 25.16%, 3.52%, 4.31%, 44.72%, and 1.57%, respectively). For edible oils, a higher oleic/linoleic (O/L) ratio and lower level of DHSA are preferred, and for industrial oils a high level of VA is preferred. Our results indicate that seeds from <i>H. cannabinus</i> may be of higher quality than <i>H. sabdariffa</i> seeds for these reasons. Significant variability in oil content and major fatty acids was also detected within both species. The variability in oil content and fatty acid composition revealed from this study will be useful for exploring seed utilization and developing new cultivars in these <i>Hibiscus</i> species

Oil, Fatty Acid, Flavonoid, and Resveratrol Content Variability and <i>FAD2A</i> Functional SNP Genotypes in the U.S. Peanut Mini-Core Collection

Peanut seeds contain high amounts of oil and protein as well as some useful bioactive phytochemicals which can contribute to human health. The U.S. peanut mini-core collection is an important genetic resource for improving seed quality and developing new cultivars. Variability of seed chemical composition within the mini-core was evaluated from freshly harvested seeds for two years. Oil, fatty acid composition, and flavonoid/resveratrol content were quantified by NMR, GC, and HPLC, respectively. Significant variability was detected in seed chemical composition among accessions and botanical varieties. Accessions were further genotyped with a functional SNP marker from the <i>FAD2A</i> gene using real-time PCR and classified into three genotypes with significantly different O/L ratios: wild type (G/G with a low O/L ratio <1.7), heterozygote (G/A with O/L ratio >1.4 but <1.7), and mutant (A/A with a high O/L ratio >1.7). The results from real-time PCR genotyping and GC fatty acid analysis were consistent. Accessions with high amounts of oil, quercetin, high seed weight, and O/L ratio were identified. The results from this study may be useful not only for peanut breeders, food processors, and product consumers to select suitable accessions or cultivars but also for curators to potentially expand the mini-core collection

Multi-Phase US Spread and Habitat Switching of a Post-Columbian Invasive, <i>Sorghum halepense</i>

<div><p>Johnsongrass (<i>Sorghum halepense</i>) is a striking example of a post-Columbian founder event. This natural experiment within ecological time-scales provides a unique opportunity for understanding patterns of continent-wide genetic diversity following range expansion. Microsatellite markers were used for population genetic analyses including leaf-optimized Neighbor-Joining tree, pairwise FST, mismatch analysis, principle coordinate analysis, Tajima’s D, Fu’s F and Bayesian clusterings of population structure. Evidence indicates two geographically distant introductions of divergent genotypes, which spread across much of the US in <200 years. Based on geophylogeny, gene flow patterns can be inferred to have involved five phases. Centers of genetic diversity have shifted from two introduction sites separated by ~2000 miles toward the middle of the range, consistent with admixture between genotypes from the respective introductions. Genotyping provides evidence for a ‘habitat switch’ from agricultural to non-agricultural systems and may contribute to both Johnsongrass ubiquity and aggressiveness. Despite lower and more structured diversity at the invasion front, Johnsongrass continues to advance northward into cooler and drier habitats. Association genetic approaches may permit identification of alleles contributing to the habitat switch or other traits important to weed/invasive management and/or crop improvement.</p></div

BAPS6 geographical clustering using Voronoi tesellations and bar representations of genotypes at three K values based on population averages (K = 2, 5, 15).

<p>State boundaries overlaid for K = 15 for visual guidance. Clustering based on individual genotypes (lower bars) is included for K = 15. The two parental species <i>Sorghum bicolor</i> and <i>Sorghum propinquum</i> are labeled as PAR.</p

Multi-Phase US Spread and Habitat Switching of a Post-Columbian Invasive, <i>Sorghum halepense</i> - Fig 2

<p><b>(a)</b> Pairwise comparisons of Nei’s distances (net and raw distances) among (lower/upper diagonal) and within (along diagonal) <i>Sorghum halepense</i> populations. <b>(b)</b> Pairwise comparisons of Fst among populations. Populations diverge as they get farther away from GA and TX. The two progenitor genotypes <i>S</i>. <i>propinquum</i>, <i>S</i>. <i>bicolor</i> and the laboratory standard <i>S</i>. <i>halepense</i> are grouped as PBH.</p

Saturation plot of <i>Sorghum halepense</i> genotypes after STRUCTURE runs based on Evanno Method (top).

<p>K values reach an asymptote between 15 and 26. DISTRUCT bar graph visualization of results after permuted by CLUMPP at four different K cluster assumptions (K = 2, 5, 15, 26). Clustering based on population averages (lower bars) and individual genotypes (upper bars). The two parental species <i>Sorghum bicolor</i> and <i>Sorghum propinquum</i> are labeled as PAR.</p

Map of sampling sites and N-J tree with an optimized leaf ordering along east–west geographical axis for <i>Sorghum halepense</i> genotypes.

<p>One of the progenitor species, <i>S</i>. <i>propinquum</i>, is used as outgroup. Colonization is outlined in 5 phases (P1-P5). Major gene flow pathways are shown using arrows in four colors (red, green, blue, gray). Initial colonization from southeastern US starting from SC (red arrows) are followed by the second introduction from AZ (S2, S4 green arrows). Gene flow from TX into NM, GA and VA (P3, blue arrows) happens concurrent with local gene flow among GA-AL-SC (P3 arrows not shown for clarity). From CA, there is a massive eastward radiation into NE, KY, FL and VA (P5a, gray arrows). While there is no detectable gene flow among KS, NE and TX (P5c) there is southbound gene flow from NE to FL (S5c, gray arrow) and KS into AL and GA (P5c, arrows not shown for clarity).</p

Contingency table showing observed frequency of <i>Sorghum halepense</i> accessions belonging to each genetic cluster, found in each habitat type (Χ² = 121.79; df = 12; P < 0.0001).

<p>Contingency table showing observed frequency of <i>Sorghum halepense</i> accessions belonging to each genetic cluster, found in each habitat type (Χ² = 121.79; df = 12; P < 0.0001).</p