Showing papers by "Susan J. Murch published in 2015"

Inoculation with arbuscular mycorrhizal fungi improves the nutritional value of tomatoes

Abstract: Arbuscular mycorrhizal (AM) fungi can affect many different micronutrients and macronutrients in plants and also influence host volatile compound synthesis. Their effect on the edible portions of plants is less clear. Two separate studies were performed to investigate whether inoculation by AM fungi (Rhizophagus irregularis, Funneliformis mosseae, or both) can affect the food quality of tomato fruits, in particular common minerals, antioxidants, carotenoids, a suite of vitamins, and flavor compounds (sugars, titratable acids, volatile compounds). It was found that AM fungal inoculation increased the nutrient quality of tomato fruits for most nutrients except vitamins. Fruit mineral concentration increased with inoculation (particularly N, P, and Cu). Similarly, inoculated plants had fruit with higher antioxidant capacity and more carotenoids. Furthermore, five volatile compounds were significantly higher in AM plants compared with non-AM controls. Taken together, these results show that AM fungi represent a promising resource for improving both sustainable food production and human nutritional needs.

A new balancing act: The many roles of melatonin and serotonin in plant growth and development

Abstract: Melatonin and serotonin are indoleamines first identified as neurotransmitters in vertebrates; they have now been found to be ubiquitously present across all forms of life. Both melatonin and serotonin were discovered in plants several years after their discovery in mammals, but their presence has now been confirmed in almost all plant families. The mechanisms of action of melatonin and serotonin are still poorly defined. Melatonin and serotonin possess important roles in plant growth and development, including functions in chronoregulation and modulation of reproductive development, control of root and shoot organogenesis, maintenance of plant tissues, delay of senescence, and responses to biotic and abiotic stresses. This review focuses on the roles of melatonin and serotonin as a novel class of plant growth regulators. Their roles in reproductive and vegetative plant growth will be examined including an overview of current hypotheses and knowledge regarding their mechanisms of action in specific responses.

Determination of β-N-methylamino-L-alanine, N-(2-aminoethyl)glycine, and 2,4-diaminobutyric acid in Food Products Containing Cyanobacteria by Ultra-Performance Liquid Chromatography and Tandem Mass Spectrometry: Single-Laboratory Validation.

Abstract: A single-laboratory validation study was completed for the determination of β-N-methylamino-L-alanine (BMAA), N-(2-aminoethyl)glycine (AEG), and 2,4-diaminobutyric acid (DAB) in bulk natural health product supplements purchased from a health food store in Canada. BMAA and its isomers were extracted with acid hydrolysis to free analytes from protein association. Acid was removed with the residue evaporated to dryness and reconstituted with derivatization using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AccQ-Fluor). Chromatographic separation and detection were achieved using RP ultra-performance LC coupled to a tandem mass spectrometer operated in multiple reaction monitoring mode. Data from biological samples were evaluated for precision and accuracy across different days to ensure repeatability. Accuracy was assessed by spike recovery of biological samples using varying amino acid concentrations, with an average recovery across all samples of 108.6%. The analytical range was found to be 764-0.746 ng/mL prior to derivatization, thereby providing a linear range compatible with potentially widely varying analyte concentrations in commercial health food products. Both the U. S. Food and Drug Administration (FDA) and U. S. Pharmacopeia definitions were evaluated for determining method limits, with the FDA approach found to be most suitable having an LOD of 0.187 ng/mL and LLOQ of 0.746 ng/mL. BMAA in the collected specimens was detected at concentrations lower than 1 μg/g, while AEG and DAB were found at concentrations as high as 100 μg/g. Finding these analytes, even at low concentrations, has potential public health significance and suggests a need to screen such products prior to distribution. The method described provides a rapid, accurate, and precise method to facilitate that screening process.

Circadian changes in endogenous concentrations of indole-3-acetic acid, melatonin, serotonin, abscisic acid and jasmonic acid in Characeae (Chara australis Brown).

Abstract: Giant-celled Characeae (Chara australis Brown), grown for 4 months on 12/12 hr day/night cycle and summer/autumn temperatures, exhibited distinct concentration maxima in auxin (indole-3-acetic acid; IAA), melatonin and serotonin about 4 hr after subjective daybreak. These concentration peaks persisted after 3 day pretreatment in continuous darkness: confirming a circadian rhythm, rather than a response to "light on." The plants pretreated for 3 d in continuous light exhibited several large IAA concentration maxima throughout the 24 hr. The melatonin and serotonin concentrations decreased and were less synchronized with IAA. Chara plants grown on 9/15 hr day/night cycle for 4 months and winter/spring temperatures contained much smaller concentrations of IAA, melatonin and serotonin. The IAA concentration maxima were observed in subjective dark phase. Serotonin concentration peaks were weakly correlated with those of IAA. Melatonin concentration was low and mostly independent of circadian cycle. The "dark" IAA concentration peaks persisted in plants treated for 3 d in the dark. The plants pretreated for 3 d in the light again developed more IAA concentration peaks. In this case the concentration maxima in melatonin and serotonin became more synchronous with those in IAA. The abscisic acid (ABA) and jasmonic acid (JA) concentrations were also measured in plants on winter regime. The ABA concentration did not exhibit circadian pattern, while JA concentration peaks were out of phase with those of IAA. The data are discussed in terms of crosstalk between metabolic pathways.

Breadfruit (Artocarpus altilis and hybrids): A traditional crop with the potential to prevent hunger and mitigate diabetes in Oceania

Abstract: More than 80% of the world's hungry live in tropical and subtropical regions where small increases in the costs of imported food, fuel and fertilizer create periods of increased food insecurity. Over time, the traditional knowledge and the traditional crops of the region are being lost and diet-based diseases such as type II diabetes are increasing in frequency. Breadfruit, Artocarpus altilis (Parkinson) Fosberg, has been a staple food and traditional crop in the Pacific for more than 3000 years and is now being cultivated for food security in the Caribbean and other tropical regions. While there is some evidence to suggest that a traditional diet based on breadfruit and other Pacific staples can prevent onset of type II diabetes, detailed scientific studies have not been conducted. One of the important issues is the wide variability in reported nutritional composition of the fruit in studies that included many different cultivars grown in widely different ecosystems. We conducted a review of the nutritional data to determine the best consensus for fruit nutrition. We identified 41 individual studies that provide some proximate, carbohydrate, vitamin and/or mineral data. A majority of the studies do not provide sufficient botanical data such as species, cultivar name, or descriptive information that would indicate the stage of maturity of the fruit or factors of the local environment such as soil composition or rainfall. Despite these shortcomings, compositional data for breadfruit suggests that it has potential to mitigate type II diabetes and obesity in Oceania and elsewhere in the tropics where breadfruit is grown. Further studies will identify specific elite cultivars recommended for this purpose.

Breadfruit (Artocarpus altilis): a source of high-quality protein for food security and novel food products

Abstract: Protein deficiency has been observed as a leading cause of malnutrition and child death in the tropics. The current study evaluated the protein quality of 49 important breadfruit cultivars (41 Artocarpus altilis and 8 hybrids of A. altilis × A. mariannensis). While significant differences were found between cultivars, all varieties contained a full spectrum of the essential amino acids and are especially rich in phenylalanine, leucine, isoleucine, and valine. The cultivar Ma’afala contained significantly higher total essential amino acid content than other varieties and higher-quality protein than staples such as corn, wheat, rice, soybean, potato, and pea.

Metabolomics for phytochemical discovery: development of statistical approaches using a cranberry model system.

Abstract: Metabolomics is the qualitative and quantitative analysis of all of the small molecules in a biological sample at a specific time and influence. Technologies for metabolomics analysis have developed rapidly as new analytical tools for chemical separations, mass spectrometry, and NMR spectroscopy have emerged. Plants have one of the largest metabolomes, and it is estimated that the average plant leaf can contain upward of 30 000 phytochemicals. In the past decade, over 1200 papers on plant metabolomics have been published. A standard metabolomics data set contains vast amounts of information and can either investigate or generate hypotheses. The key factors in using plant metabolomics data most effectively are the experimental design, authentic standard availability, extract standardization, and statistical analysis. Using cranberry (Vaccinium macrocarpon) as a model system, this review will discuss and demonstrate strategies and tools for analysis and interpretation of metabolomics data sets including eli...

Evaluation of ploidy variations in Hypericum perforatum L. (St. John’s wort) germplasm from seeds, in vitro germplasm collection, and regenerants from floral cultures

Abstract: Hypericum perforatum L. (St. John’s wort) is an important medicinal herb and a subject of intensive research for its complex and diverse bioactive chemicals. An in vitro-grown germplasm collection of elite H. perforatum lines, established to provide easy access to physiologically uniform plants, was used for ploidy assessment studies. Germplasm lines were maintained by repeated subculture of shoot tips for over 10 yr with little change in their capacity to produce multiple shoots. Shoots of four of these lines were rooted and grown in the greenhouse to obtain plants to provide anther and filament explants. Culture of explants on a regeneration medium supplemented with 1 mg L−1 α-naphthaleneacetic acid (NAA) and 1 mg L−1 6-benzylaminopurine (BA) induced large numbers of calluses and shoots on all explants. Flow cytometric (FCM) analysis of nuclei samples revealed that the nuclear DNA contents of calluses and shoots developed from anther and filament explants of germplasm lines were not significantly different from those of the donor plants. FCM screening of in vitro-maintained germplasm lines in the collection showed that they had similar nuclear DNA amounts and were all tetraploid (2n = 4x). Analysis of seedlings obtained from the original seed source used to derive the germplasm lines showed that ~11% of them were hexaploid (2n = 6x). Data obtained from FCM screens confirmed the preservation of tetraploidy in in vitro-maintained H. perforatum germplasm and the regenerants obtained from male floral organs. The consistent ploidy of the H. perforatum plants of in vitro origin further supports the usefulness of such technologies to ensure genetic uniformity of medicinal plants over extended periods of culture and may facilitate long-term preservation of their elite clones.

Liquid chromatography and mass spectrometry for the analysis of N-β-methylamino-L-alanine with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate.

Abstract: Numerous studies in the past decade have identified N-β-methylamino-L-alanine (BMAA) as a putative environmental neurotoxin. Produced by cyanobacteria and accumulated at different levels of the trophic system, BMAA has been detected in the brain tissue of human patients that died from progressive neurodegenerative disease. Research into the mechanism of neurotoxicity has been hampered by conflicting results and disagreement in the literature over analytical methods used for quantification and detection. While several research approaches have been tested, the use of the derivatizing reagent 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate is presented here as an effective and selective means for the analysis of BMAA and two co-occurring biological isomers, DAB and AEG, by liquid chromatography and tandem mass spectrometry.

Systems Biology Analysis of Changes in Potential Across Plasma Membrane: Physiological Implications

Abstract: Variation of the membrane potential difference (PD) across plasma membrane is considered in terms of one or more ion transporter populations changing their conductance and activation kinetics. Slow changes occurring over minutes can be investigated by the current voltage (I/V) technique. In some cases, data are sufficient to model electrical characteristics of each transporter population and their evolution with time. The proton pump at the plasma membrane of the salt-sensitive Characeae Chara australis provides an example of single transporter changing conductance against a steady background. The rise and fall in proton pump conductance may be prompted by circadian oscillations of indoleamines IAA and melatonin, measured in growing thalli of characean plants. In response to abiotic stress, two or more transporter populations change conductance and/or PD dependence. The voltage clamp to extreme negative PD levels transiently inhibits the proton pump in C. australis, activating H+/OH− channels, increasing the background conductance, and opening inward rectifier channels at more depolarized PDs. An increase in medium salinity (after pre-treatment with isotonic sorbitol medium) results in similar response, which is preceded by a typical noise in membrane PD. In salt-tolerant Characeae Lamprothamnium sp., increase in salinity (or osmolarity) provokes an increase in proton pumping as well as increase in background conductance and opening of the inward rectifier channels at more depolarized PDs to effect turgor regulation. The hypoosmotic turgor regulation also involves a complex interaction of several transporters, initiated by the increase of turgor pressure , [Ca2+]cyt increase, and PD changes. A detailed modeling is in progress for most of these responses. The examples demonstrate the analytical and predictive power of the I/V methodology coupled with the systems biology modeling and monitoring of biochemical changes.