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Tupelo, MS, United States

Zheljazkov V.D.,Oregon State University | Gawde A.,Natural Products Utilization Research Unit | Cantrell C.L.,Natural Products Utilization Research Unit | Astatkie T.,Dalhousie University | Schlegel V.,University of Nebraska - Lincoln

A steam distillation extraction kinetics experiment was conducted to estimate essential oil yield, composition, antimalarial, and antioxidant capacity of cumin (Cuminum cyminum L.) seed (fruits). Furthermore, regression models were developed to predict essential oil yield and composition for a given duration of the steam distillation time (DT). Ten DT durations were tested in this study: 5, 7.5, 15, 30, 60, 120, 240, 360, 480, and 600 min. Oil yields increased with an increase in the DT. Maximum oil yield (content, 2.3 g/100 seed), was achieved at 480 min; longer DT did not increase oil yields. The concentrations of the major oil constituents α-pinene (0.14-0.5% concentration range), β-pinene (3.7-10.3% range), γ-cymene (5-7.3% range), γ-Terpinene (1.8-7.2% range), cumin aldehyde (50-66% range), α-Terpinen-7-Al (3.8-16% range), and β-Terpinen-7-Al (12-20% range) varied as a function of the DT. The concentrations of α-pinene, β-pinene, γ-cymene, γ-Terpinene in the oil increased with the increase of the duration of the DT; α-pinene was highest in the oil obtained at 600 min DT, β-pinene and γ-Terpinene reached maximum concentrations in the oil at 360 min DT; γ-cymene reached a maximum in the oil at 60 min DT, cumin aldehyde was high in the oils obtained at 5-60 min DT, and low in the oils obtained at 240-600 min DT, α-Terpinen-7-Al reached maximum in the oils obtained at 480 or 600 min DT, whereas β-terpinen-7-Al reached a maximum concentration in the oil at 60 min DT. The yield of individual oil constituents (calculated from the oil yields and the concentration of a given compound at a particular DT) increased and reached a maximum at 480 or 600 min DT. The antimalarial activity of the cumin seed oil obtained during the 0-5 and at 5-7.5 min DT timeframes was twice higher than the antimalarial activity of the oils obtained at the other DT. This study opens the possibility for distinct marketing and utilization for these improved oils. The antioxidant capacity of the oil was highest in the oil obtained at 30 min DT and lowest in the oil from 360 min DT. The Michaelis-Menton and the Power nonlinear regression models developed in this study can be utilized to predict essential oil yield and composition of cumin seed at any given duration of DT and may also be useful to compare previous reports on cumin oil yield and composition. DT can be utilized to obtain cumin seed oil with improved antimalarial activity, improved antioxidant capacity, and with various compositions. Source

Ribeiro D.N.,Mississippi State University | Pan Z.,Natural Products Utilization Research Unit | Duke S.O.,Natural Products Utilization Research Unit | Nandula V.K.,Crop Production Systems Research Unit | And 3 more authors.

The inheritance of glyphosate resistance in two Amaranthus palmeri populations (R1 and R2) was examined in reciprocal crosses (RC) and second reciprocal crosses (2RC) between glyphosate-resistant (R) and -susceptible (S) parents of this dioecious species. R populations and Female-R × Male-S crosses contain higher 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene copy numbers than the S population. EPSPS expression, EPSPS enzyme activity, EPSPS protein quantity, and level of resistance to glyphosate correlated positively with genomic EPSPS relative copy number. Transfer of resistance was more influenced by the female than the male parent in spite of the fact that the multiple copies of EPSPS are amplified in the nuclear genome. This led us to hypothesize that this perplexing pattern of inheritance may result from apomictic seed production in A. palmeri. We confirmed that reproductively isolated R and S female plants produced seeds, indicating that A. palmeri can produce seeds both sexually and apomictically (facultative apomixis). This apomictic trait accounts for the low copy number inheritance in the Female-S × Male-R offsprings. Apomixis may also enhance the stability of the glyphosate resistance trait in the R populations in the absence of reproductive partners. © 2013 Springer-Verlag Berlin Heidelberg. Source

Zheljazkov V.D.,Mississippi State University | Zheljazkov V.D.,University of Wyoming | Cantrell C.L.,Natural Products Utilization Research Unit | Astatkie T.,Dalhousie University | Cannon J.B.,Natural Products Utilization Research Unit
Agronomy Journal

Lemongrass [Cymbopogon flexuosus (Steud.) Wats, (syn. Andropogon nardus var. flexuosus Hack; A. flexuosus Nees)] is one of the most widely grown essential oil plants in the world. Field experiments were conducted at Verona and Poplarville, MS, to evaluate the effects of N (0, 40, 80, and 160 kg N/ha) and S (0, 30, 60, and 90 kg S/ha) on lemongrass biomass productivity, essential oil content, yield, and oil composition. Overall, the essential oil content varied within 0.35 to 0.6% of the dried biomass. The major constituents were geranial (25-53%), neral (20-45%), caryophyllene oxide (1.3-7.2%), and t-caryophyllene (0.3-2.2%). Biomass yields at Verona ranged from 9486 to 19,375 kg/ha, while oil yields ranged from 30 to 139 kg/ha. Overall, dry weight yields increased with the application of 80 kg N/ha relative to the 0 kg N/ha and with 160 kg of N/ha relative to the 0 and 40 kg N/ha treatments. At Poplarville, biomass yields varied from 8036 to 12,593 kg/ha, while oil yields ranged from 23.5 to 89.5 kg/ha. The application of N at 160 kg/ha at Poplarville increased dry weight yields relative to the N at 0 or 40 kg/ha rates, irrespective of the rate used for S. At Verona, within each S application rate, biomass yields were highest in Harvest 2, lower in Harvest 1, and the lowest in Harvest 3 (regrowth). The combined biomass yields of Harvest 1 and Harvest 3 would be lower, but oil yields would be higher compared to Harvest 2 (single-harvest system). Lemongrass can be grown as an annual essential oil crop in the southeastern United States, with a potential for dual utilization: essential oil and lignocellulosic material for ethanol production. © 2011 by the American Society of Agronomy. Source

Bajsa J.,Natural Products Utilization Research Unit | Pan Z.,Natural Products Utilization Research Unit | Duke S.O.,Natural Products Utilization Research Unit
Plant Signaling and Behavior

Depending on the threat to a plant, different pattern recognition receptors, such as receptor-like kinases, identify the stress and trigger action by appropriate defense response development. 1,2 The plant immunity system primary response to these challenges is rapid accumulation of phytohormones, such as ethylene (ET), salicylic acid (SA) and jasmonic acid (JA) and its derivatives. These phytohormones induce further signal transduction and appropriate defenses against biotic threats. 3,4 Phytohormones play crucial roles not only in the initiation of diverse downstream signaling events in plant defense but also in the activation of effective defenses through an essential process called signaling pathway crosstalk, a mechanism involved in transduction signals between two or more distinct, "linear signal transduction pathways simultaneously activated in the same cell." 5. © 2011 Landes Bioscience. Source

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