Supplemental UV-B Exposure Influences the Biomass and the Content of Bioactive Compounds in Linum usitatissimum L. Sprouts and Microgreens

The interest in the pre-harvest ultraviolet-B (UV-B) exposure of crops in indoor cultivation has grown consistently, though very little is known about its influence on the nutraceutical quality of microgreens. Flaxseeds constitute a valuable oilseed species, mostly appreciated for their nutritional properties and the presence of health-promoting compounds. Therefore, although scarcely studied, flaxseed sprouts and microgreens might constitute a high-quality food product to be included in a healthy diet. This study aims to unravel the effects of pre-harvest ultraviolet-B irradiation on the nutritional and nutraceutical quality of flaxseed sprouts and microgreens grown under artificial conditions. The UV-B irradiation decreased the biomass and stem length of microgreens. However, the content of total phenolics and flavonoids and the antioxidant capacity were strongly enhanced by the UV-B treatment in both sprouts and microgreens. Among photosynthetic pigments, chlorophyll a, violaxanthin, antheraxanthin, and lutein in sprouts were reduced by the treatment, while chlorophyll b increased in microgreens. In conclusion, our results showed that growing flaxseed sprouts and microgreens in controlled conditions with supplemental UV-B exposure might increase their nutritional and nutraceutical quality, as well as their antioxidant capacity, making them high-quality functional foods

Comparing induction at an early and late step in signal transduction mediating indirect defence in Brassica oleracea

The induction of plant defences involves a sequence of steps along a signal transduction pathway, varying in time course. In this study, the effects of induction of an early and a later step in plant defence signal transduction on plant volatile emission and parasitoid attraction are compared. Ion channel-forming peptides represent a class of inducers that induce an early step in signal transduction. Alamethicin (ALA) is an ion channel-forming peptide mixture from the fungus Trichoderma viride that can induce volatile emission and increase endogenous levels of jasmonic acid (JA) and salicylic acid in plants. ALA was used to induce an early step in the defence response in Brussels sprouts plants, Brassica oleracea var. gemmifera, and to study the effect on volatile emission and on the behavioural response of parasitoids to volatile emission. The parasitoid Cotesia glomerata was attracted to ALA-treated plants in a dose-dependent manner. JA, produced through the octadecanoid pathway, activates a later step in induced plant defence signal transduction, and JA also induces volatiles that are attractive to parasitoids. Treatment with ALA and JA resulted in distinct volatile blends, and both blends differed from the volatile blends emitted by control plants. Even though JA treatment of Brussels sprouts plants resulted in higher levels of volatile emission, ALA-treated plants were as attractive to C. glomerata as JA-treated plants. This demonstrates that on a molar basis, ALA is a 20 times more potent inducer of indirect plant defence than JA, although this hormone has more commonly been used as a chemical inducer of plant defence

Infochemical use in Brassica-insect interactions : a phenotypic manipulation approach to induced plant defences

Plants have developed a range of strategies to defend themselves against herbivore attack. Defences can be constitutive, i.e. always present independent of attack, or induced, i.e. only elicited when the plant is under attack. In this thesis, I focused on induced chemical defence responses of plants and the response of associated insects to these phenotypic changes in plants. Herbivore attack is known to induce chemical defences in Brassicaceous plants. Using several elicitors and inhibitors of different steps of the signalling pathways underlying herbivore-induced plant responses, I studied how induced infochemicals affect interactions with associated insects. Jasmonic acid (JA) is a key plant hormone in the octadecanoid signalling pathway known to be involved in herbivore-induced plant defences. Application of JA can induce plant responses that are similar, although not identical, to herbivore feeding. Two specialist herbivores of Brassicaceous plants, the butterflies Pieris rapae and P. brassicae, preferred to oviposit on non-induced plants over JA-induced plants. Development of P. rapae caterpillars was shown to be reduced, suggesting that oviposition avoidance on JA-induced plants is adaptive. The levels of glucosinolates, secondary metabolites of Brassicaceous plants that are used by Pieris butterflies as oviposition stimulants, could not explain the observed oviposition preference of the butterflies. JA-induced changes in the plants also affected members of the third trophic level. Volatile emission of JA-induced plants attracted parasitoid wasps to the plants. Parasitoid attraction to JA-induced plants was shown to depend on dose and induction time. However, using JA to induce phenotypic changes had effects different from those induced by herbivores, both chemically and ecologically. Volatile emission of JA-induced and herbivore-induced plants differed; whereas JA-induced plants emitted larger amounts of volatiles, the parasitoids preferred herbivore-induced plants over JA-treated ones. Early events in plant defence responses, involved in attacker recognition, are damage-induced modulations of ion channel activities resulting in ion imbalances. The fungal elicitor alamethicin, an ion channel-forming peptide mixture, was used to mimic early steps in defence responses. Alamethicin treatment increased attractiveness of plants to parasitoid wasps. Although volatile emission of alamethicin-treated plants was much lower, they were equally attractive as JA-treated plants. This indicates that quality rather than quantity of induced plant volatile blends is important to parasitoids. Besides chemical elicitation of herbivore-induced responses, which is a widely applied approach, plant defence responses can also be chemically inhibited. This provides the opportunity to inhibit the rate of specific enzymatic steps in a signal-transduction pathway. Furthermore, visual cues associated with feeding damage can be present (and similar) in control- and inhibitor-treated plants. Phenidone is a compound that inhibits lipoxygenase, an enzyme catalyzing an early step in the octadecanoid pathway. Parasitoid attraction was reduced when the plants were treated with phenidone before infestation. Also herbivore oviposition preference was shown to be affected by inhibition of this signalling pathway. Herbivores can differ in their oviposition preferences. I studied two specialist herbivores with different oviposition preferences: Pieris brassicae avoids oviposition on herbivore-induced plants, whereas Plutella xylostella prefers to oviposit on Pieris-infested plants. I showed that these preferences have a chemical basis and are dependent on octadecanoid signalling, since treatment with the lipoxygenase inhibitor phenidone eliminated herbivore-induced oviposition avoidance or preference. Thus far, most of the studies on induced plant defences have been done with vegetative plants. However, since reproduction and defence are both processes that require energy and nutrients, this could result in a trade-off. Herbivore feeding on leaves, flowers or roots is known to affect pollinator visitation, but the mechanisms mediating this change have not been addressed. Effects of induction with JA on nectar secretion and pollinator visitation to flowers were investigated. JA-induced plants secreted less nectar, but the sugar concentrations did not change. Also visitation of honeybees and syrphid flies did not change upon JA induction. These results show the complexity of induced plant defence responses and the variety of behavioural responses of insects on different trophic levels. Combining the phenotypic manipulation approach to induced plant defences, as used in this thesis, with molecular genetic techniques and building on recent developments in plant biochemistry provides a promising way forward towards enhanced understanding of the intricate interactions between plants and insects. <br/

Does Dietary Melatonin Play a Role in Bone Mineralization?

Introduction: Melatonin is generated as a product of normal circadian rhythm and is also is thought to play an important role in maintaining bone mineral density (BMD) by reducing chronic inflammation. Postmenopausal women are at an elevated risk of BMD loss due to declining estrogen and a natural decrease in melatonin synthesis with increasing age. Endogenous melatonin production is largely influenced by exposure to external light cues, but recent research has indicated that serum melatonin may be increased by the consumption of melatonin-rich foods. The purpose of this study was to quantify dietary-derived melatonin and examine its effects on inflammation, BMD, and sleep in a sample of postmenopausal women. Methods: Cross-sectional analysis of data from the National Health and Nutrition Examination Survey (NHANES) was conducted to examine differences in melatonin consumption, BMD, and sleep in postmenopausal women with chronic and low-level inflammation indicated by level of C-reactive protein (CRP). Data from the years 2005-2010 was included in this study. Results: 110 postmenopausal women were included in the analysis with 55 subjects included in each inflammatory group. Individuals with normal CRP had a significantly greater intake of dietary melatonin (p=0.03) and higher BMD (p\u3c0.05) than individuals with chronic inflammation. Normal inflammatory subjects also had a significantly higher intake of folate (p\u3c0.0001), vitamin B6 (p=0.0005), and magnesium (p=0.0005) than subjects with chronic inflammation. Hours of sleep did not differ significantly with CRP level (p=1.0). Individuals with chronic inflammation exhibited a negative correlation between BMD and CRP (r= -0.27, p=0.04). Conclusions: The results suggest that dietary-derived melatonin may play an underlying role in mitigating inflammation and increasing BMD in postmenopausal women by reducing inflammation and oxidative stress. Melatonin may enhance the effects of other antioxidants and anti-inflammatory nutrients, and is part of dietary patterns rich in plant foods. Foods with melatonin also contain a variety of nutrients that act as coenzymes and cofactors for synthesis of endogenous melatonin

TIME-DEPENDENT DETERMINATIVE BIOCHEMICAL TRAITS FOR SALT TOLERANCE MECHANISM IN MUNGBEAN (Vigna radiata (L.) R. WILCZEK)

Mungbean is one of the commercially valuable pulse crops. Time-dependent biochemical modulations in the mungbean varieties PKV AKM 12-28 and VBN (Gg)3 exposed to 75, 100, and 125 mM NaCl were estimated, and the results were concluded through multivariate modeling. The cluster analysis gave two fairly distinct clusters that had similar biochemical responses. Results on the principal component analysis suggested that protein content (PC), total phenolic content (TPC), total flavonoid content (TFC), DPPH radical scavenging activity, ABTS radical scavenging activity, proline content (PRC), total free amino acid (TFAA) content, and malondialdehyde (MDA) contents were dominant traits in the shoot as compared to the root. These can be taken as the primary indicators to assess the effect of salt stress on mungbean varieties. The discriminant analysis had identified TFC, MDA, and total sugar content (TSC) as discriminating variables between the roots and shoots. Further, MDA and TFC were identified as discriminating variables under different salt concentrations, and TSC was identified as a discriminating variable at different exposure durations. Discriminant partial least squares analysis further identified optimum biochemical modulations in the shoots of PKV AKM 12-28 and 75 mM NaCl. The salt treatment produced a strong biochemical modulation after 30 and 45 days, which helped plants survive under salt stress. The multivariate approaches efficiently interpreted time-dependent biochemical modulations in shoots and roots of mungbean varieties under salt stress

Improving photosynthetic efficiency and plant growth in controlled environments: the role of light quality, biostimulant application and ionising radiation

The possibility of growing higher plants, especially crops, in controlled environments allows reducing the variability of plant responses to the multiple stress occurring in the field and increasing the primary production. Among variables implicated in plant development and physiology, light represents a driver. Therefore, selecting specific wavelengths of visible light to obtain appropriate light quality regimes may significantly improve photosynthesis, biomass production, and secondary metabolites synthesis, resulting in an enrichment of food quality (in terms of nutraceutical compounds and antioxidants) and plant tolerance against abiotic stresses. The use of the light quality as 'natural fertiliser' alone or combined with other eco-friendly practices such as the employment of biostimulants could be a promising solution to enhance crop productivity preserving the overexploitation of soil and reducing the overuse of agrochemicals. The light spectrum modulation within growth chambers or vertical farms may find proper applications in the cultivation of crops in extreme environments on the Earth, such as hot or cold deserts or in the Space environment. This latter is highly unhospitable because it is characterised by many unfavourable ecological factors, including microgravity and cosmic radiations. In particular, ionising radiation is one of the significant constraints preventing plant growth and survival in Space. In the Bioregenerative Life Support Systems (BLSSs), conceived to sustain human life in Space, plants will have a crucial role in food production and air regeneration and CO2 removal. Thus, in the next future, the challenge to grow plants in Space must consider studying the effect of Space ionising radiation not only on humans and animals but also on plants. The PhD project is focused on the role of light quality in regulating the photosynthetic machinery of higher plants in controlled environments. In particular, it has been explored if and how specific light wavelengths during growth may modify plant physiological behaviour and phytochemical production in response to biostimulant application or exposure to ionising radiation. Among different variables affecting plant growth, biostimulants application was selected with the specific aim to improve the overall plant physiological performance in terms of primary and secondary metabolism in the context of sustainable agricultural practices. The ionising radiation was chosen as a space stress environmental factor in the view of experiments finalised to plant cultivation in Space. The experiments were carried out on widely consumed crops such as tomato, spinach, soybean and chard, considered important functional foods. Plants were grown in dedicated growth chambers under specific temperature, relative humidity, photoperiod, and light intensity condition, modulating the light spectrum to obtain specific light regimes promoting the photosynthetic performance. The outcomes of these experiments were utilised in the subsequent trials to test how light quality combined with ionising radiation or growth-promoting agents, i.e., biostimulants, may modify photosynthesis and antioxidant production. A downscaling investigative approach was adopted to analyse plant responses at different scale levels from cells and tissues to the whole organism. The outcomes of this research may have implications not only for developing sustainable protocols for indoor cultivation but also for plant growth in extreme environments on Earth and Space, such as the orbiting stations

Application of Liquid Chromatography in Food Analysis

Food products are very complex mixtures consisting of naturally occurring compounds and other substances, generally originating from technological processes, agrochemical treatments, or packaging materials. However, food is no longer just a biological necessity for survival. Society demands healthy and safe food, but it is also increasingly interested in other quality attributes more related to the origin of the food, the agricultural production processes used, the presence or not of functional compounds, etc. Improved methods for the determination of authenticity, standardization, and efficacy of nutritional properties in natural food products are required to guarantee their quality and for the growth and regulation of the market. Nowadays, liquid chromatography with ultraviolet detection, or coupled to mass spectrometry and high-resolution mass spectrometry, are among the most powerful techniques to address food safety issues and to guarantee food authenticity in order to prevent fraud. The aim of this book is to gather review articles and original research papers focused on the development of analytical techniques based on liquid chromatography for the analysis of food. This book is comprised of six valuable scientific contributions, including five original research manuscripts and one review article, dealing with the employment of liquid chromatography techniques for the characterization and analysis of feed and food, including fruits, extra virgin olive oils, confectionery oils, sparkling wines and soybeans

Characterizing Intense Pulsed Light-Elicited Effects on Escherichia coli and Non-Fat Dry Milk Through Metabolomic and Chemometric Analysis

University of Minnesota M.S. thesis.September 2019. Major: Nutrition. Advisor: Chi Chen. 1 computer file (PDF); viii, 83 pages.Disinfecting powder food is challenging due to their low water activity. Intense-pulsed light (IPL) is advantageous in achieving efficient bacterial reduction. Its mechanisms of mediating bactericidal effect has been characterized as inducing DNA damage and disrupting cell structure integrity. A novel IPL platform is being constructed and studied to achieve high disinfecting efficacy while maintaining the physiochemical properties of the powder food. However, little is known about its influence on cell metabolism, which is essential for cell survival and growth. E.coli K-12 culture from overnight incubation were treated with a bactericidal dose of IPL for different durations. After centrifugation, the metabolites in bacterial pellets were extracted by a mixture of chloroform, methanol, and water. Aqueous and lipid extracts were examined by liquid chromatography-mass spectrometry (LC-MS)-based metabolomic analysis. The principal components analysis (PCA) of LC-MS data indicated that the metabolome of E. coli was dramatically affected by IPL treatment in a time-dependent pattern. Multiple nucleotides, antioxidants, and membrane components, including adenosine monophosphate, glutathione, and menaquinone-8, were identified as the metabolites sensitive to IPL treatment. These markers revealed IPL-induced membrane damage and oxidative stress. Additional markers suggest IPL hindered ability of repairing DNA damage. New information from untargeted metabolomic analysis provides useful insights on the mechanism of IPL-elicited bactericidal activities. An ideal IPL treatment is expected to achieve pasteurization with minimal influences on physical, chemical, and nutritional properties of powdered food. While IPL showed effective bactericidal effect, it is also essential to evaluate its influence on the food matrix. IPL-irradiated non-fat dry milk was prepared by solvent extraction and acid hydrolysis, and then examined by liquid chromatography-mass spectrometry (LC-MS) analysis. Targeted and untargeted chemometric analysis were performed to determine the chemical compositions of prepared samples and the effects of IPL treatment. Targeted chemometric analysis indicated that IPL treatment in this study did not significantly affect the amino acid composition of non-fat dairy milk powder. However, the multivariate models constructed by untargeted chemometric analysis of extracted samples revealed the dose-dependent chemical changes after IPL treatment. IPL treatment directly degraded riboflavin, and led to formation of peptides as a result of photolysis of milk proteins. Untargeted chemometric analysis on the chemical effects of IPL treatment will provide useful information to guide the development of IPL disinfection technology