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Uquiche E.,University of the Frontier | Uquiche E.,Agriaquaculture Nutritional Genomic Center | Martinez M.,University of the Frontier
Industrial Crops and Products | Year: 2016

Leptocarpha rivularis is a medicinal plant used as a treatment for different illnesses. These properties are related to its essential oils. Trichomes are specialized structures located on the leaf surface and are responsible for secreting essential oils. Disruption of trichomes by CO2 rapid depressurization was studied as pretreatment of L. rivularis leaves for subsequent extraction of essential oil with supercritical CO2 at 40 °C and 10 MPa. The effect of temperature (21-49 °C) and pressure (6-13 MPa) of static compression on extract recovery was studied. Low temperature and high pressure favored the highest extract recovery, with the pressure effect being more important than the temperature effect. Disruption of trichomes was evidenced by light microscopy images of pretreated leaves. Antioxidant activity in the selected extract, measured as Trolox equivalent (TE) and β-carotene bleaching (IC50 value), were 1.85 mmol TE/kg and 8.7 mg/mL respectively. The anti-inflammatory activity (IC50 value) was 1.12 mg/mL. Three target terpenoids of L. rivularis (α-thujone, β-caryophyllene and caryophyllene oxide) were quantified in the selected extract using GC/FID. Pretreatment by CO2 rapid depressurization can improve the recovery of important compounds from L. rivularis leaves, and since this is performed at a low temperature, this protects heat-sensitive compounds. © 2015 Elsevier B.V. Source

Soto-Cerda B.J.,University of Manitoba | Soto-Cerda B.J.,Agriculture and Agri Food Canada | Soto-Cerda B.J.,Agriaquaculture Nutritional Genomic Center | Diederichsen A.,Agriculture and Agri Food Canada | And 4 more authors.
BMC Plant Biology | Year: 2013

Background: Flax is valued for its fiber, seed oil and nutraceuticals. Recently, the fiber industry has invested in the development of products made from linseed stems, making it a dual purpose crop. Simultaneous targeting of genomic regions controlling stem fiber and seed quality traits could enable the development of dual purpose cultivars. However, the genetic diversity, population structure and linkage disequilibrium (LD) patterns necessary for association mapping (AM) have not yet been assessed in flax because genomic resources have only recently been developed. We characterized 407 globally distributed flax accessions using 448 microsatellite markers. The data was analyzed to assess the suitability of this core collection for AM. Genomic scans to identify candidate genes selected during the divergent breeding process of fiber flax and linseed were conducted using the whole genome shotgun sequence of flax.Results: Combined genetic structure analysis assigned all accessions to two major groups with six sub-groups. Population differentiation was weak between the major groups (FST = 0.094) and for most of the pairwise comparisons among sub-groups. The molecular coancestry analysis indicated weak relatedness (mean = 0.287) for most individual pairs. Abundant genetic diversity was observed in the total panel (5.32 alleles per locus), and some sub-groups showed a high proportion of private alleles. The average genome-wide LD (r2) was 0.036, with a relatively fast decay of 1.5 cM. Genomic scans between fiber flax and linseed identified candidate genes involved in cell-wall biogenesis/modification, xylem identity and fatty acid biosynthesis congruent with genes previously identified in flax and other plant species.Conclusions: Based on the abundant genetic diversity, weak population structure and relatedness and relatively fast LD decay, we concluded that this core collection is suitable for AM studies targeting multiple agronomic and quality traits aiming at the improvement of flax as a true dual purpose crop. Our genomic scans provide the first insights into candidate regions affected by divergent selection in flax. In combination with AM, genomic scans have the ability to increase the power to detect loci influencing complex traits. © 2013 Soto-Cerda et al.; licensee BioMed Central Ltd. Source

Soto-Cerda B.J.,Agriculture and Agri Food Canada | Soto-Cerda B.J.,Agriaquaculture Nutritional Genomic Center | Cloutier S.,Agriculture and Agri Food Canada
Plant Molecular Biology Reporter | Year: 2013

Genomic microsatellites (gSSRs) and expressed sequence tag-derived SSRs (EST-SSRs) have gained wide application for elucidating genetic diversity and population structure in plants. Both marker systems are assumed to be selectively neutral when making demographic inferences, but this assumption is rarely tested. In this study, three neutrality tests were assessed for identifying outlier loci among 150 SSRs (85 gSSRs and 65 EST-SSRs) that likely influence estimates of population structure in three differentiated flax sub-populations (F ST = 0.19). Moreover, the utility of gSSRs, EST-SSRs, and the combined sets of SSRs was also evaluated in assessing genetic diversity and population structure in flax. Six outlier loci were identified by at least two neutrality tests showing footprints of balancing selection. After removing the outlier loci, the STRUCTURE analysis and the dendrogram topology of EST-SSRs improved. Conversely, gSSRs and combined SSRs results did not change significantly, possibly as a consequence of the higher number of neutral loci assessed. Taken together, the genetic structure analyses established the superiority of gSSRs to determine the genetic relationships among flax accessions, although the combined SSRs produced the best results. Genetic diversity parameters did not differ statistically (P > 0.05) between gSSRs and EST-SSRs, an observation partially explained by the similar number of repeat motifs. Our study provides new insights into the ability of gSSRs and EST-SSRs to measure genetic diversity and structure in flax and confirms the importance of testing for the occurrence of outlier loci to properly assess natural and breeding populations, particularly in studies considering only few loci. © 2013 The Author(s). Source

Millao S.,University of the Frontier | Uquiche E.,University of the Frontier | Uquiche E.,Agriaquaculture Nutritional Genomic Center
Journal of Supercritical Fluids | Year: 2016

Nannochloropsis gaditana is a microalga characterized by its high lipid content and as an important source of carotenoids, recognized as potent natural antioxidants. The objective of this work was to study the effects of temperature (36-64°C) and CO2 density (914-956 kg/m3) on the content of carotenoids and tocopherols (minor lipids), and the antioxidant activity of oil extracted from N. gaditana using supercritical CO2. Antioxidant activity was measured by the DPPH assay, FRAP assay and β-carotene bleaching assay. A process development unit was used for extraction experiments, performed under a central composite rotatable design. The experimental data were analyzed by means of the response surface methodology. Content of carotenoids and tocopherols showed differences of 1.5- and 2.3-fold, respectively. The minor lipid content and the antioxidant activity increased with the increase of the temperature and CO2 density, reaching the highest values at 64°C and 956 kg/m3 for all responses studied. Important antioxidant properties in the oil showed a positive correlation with the content of minor lipids. © 2016 Elsevier B.V. All rights reserved. Source

Uquiche E.,University of the Frontier | Uquiche E.,Agriaquaculture Nutritional Genomic Center | Garces F.,University of the Frontier
Journal of Supercritical Fluids | Year: 2016

We studied the effects of temperature (40, 50, and 60 °C) and pressure (9, 12, and 15 MPa) on the recovery and antioxidant activity of the essential oil from Leptocarpha rivularis leaves by supercritical CO2 using a 32 factorial design. Experimental data were analyzed with the response surface methodology. Extraction yield varied from 23.5 to 42.6 g/kg d.s., and the resultant antioxidant activity (DPPH assay) varied from 0.60 to 1.84 mmol TE/kg. The highest extraction yield and antioxidant activity in the supercritical extract at 40 °C and 15 MPa, respectively 2.5 and 5 times higher than in hydrodistilled extract. However, the extraction yield and antioxidant activity of a hydroethanolic extract were higher than those of supercritical extracts. Three target terpenoids of L. rivularis (α-thujone, β-caryophyllene and caryophyllene oxide) were quantified in the supercritical extract using GC/FID; they were not detected in the hydroethanolic extract. © 2015 Elsevier B.V. All rights reserved. Source

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