ATR-FTIR Spectroscopy-Linked Chemometrics:A Novel Approach to the Analysis and Control of the Invasive Species Japanese Knotweed

Japanese knotweed (Reynoutria japonica), an invasive plant species, causes negative environmental and socio-economic impacts. A female clone in the United Kingdom, its extensive rhizome system enables rapid vegetative spread. Plasticity permits this species to occupy a broad geographic range and survive harsh abiotic conditions. It is notoriously difficult to control with traditional management strategies, which include repetitive herbicide application and costly carbon-intensive rhizome excavation. This problem is complicated by crossbreeding with the closely related species, Giant knotweed (Reynoutria sachalinensis), to give the more vigorous hybrid, Bohemian knotweed (Fallopia x Bohemica) which produces viable seed. These species, hybrids, and backcrosses form a morphologically similar complex known as Japanese knotweed ‘sensu lato’ and are often misidentified. The research herein explores the opportunities offered by advances in the application of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy-linked chemometrics within plant sciences, for the identification and control of knotweed, to enhance our understanding of knotweed biology, and the potential of this technique. ATR-FTIR spectral profiles of Japanese knotweed leaf material and xylem sap samples, which include important biological absorptions due to lipids, proteins, carbohydrates, and nucleic acids, were used to: identify plants from different growing regions highlighting the plasticity of this clonal species; differentiate between related species and hybrids; and predict key physiological characteristics such as hormone concentrations and root water potential. Technical advances were made for the application of ATR-FTIR spectroscopy to plant science, including definition of the environmental factors that exert the most significant influence on spectral profiles, evaluation of sample preparation techniques, and identification of key wavenumbers for prediction of hormone concentrations and abiotic stress. The presented results cement the position of concatenated mid-infrared spectroscopy and machine learning as a powerful approach for the study of plant biology, extending its reach beyond the field of crop science to demonstrate a potential for the discrimination between and control of invasive plant species

Application of Analytical Chemistry to Foods and Food Technology

The application of analytical chemistry to the food sector allows the determination of the chemical composition of foods and the properties of their constituents, contributing to the definition of their nutritional and commodity value. Furthermore, it is possible to study the chemical modifications that food constituents undergo as a result of the treatments they undergo (food technology). Food analysis, therefore, allows us not only to determine the quality of a product or its nutritional value, but also to reveal adulterations and identify the presence of xenobiotic substances potentially harmful to human health. Furthermore, some foods, especially those of plant origin, contain numerous substances with beneficial effects on health. While these functional compounds can be obtained from a correct diet, they can also be extracted from food matrices for the formulation of nutraceutical products or added to foods by technological or biotechnological means for the production of functional foods. On the other hand, the enormous growth of the food industry over the last 50 years has broadened the field of application of analytical chemistry to encompass not only food but also food technology, which is fundamental for increasing the production of all types of food

Integrative Advances in Rice Research

This book describes some recent advances in rice research in terms of crop breeding and improvement (Section 1), crop production and protection (Section 2), and crop quality control and food processing (Section 3). It contains fourteen chapters that cover such topics as two-line rice breeding in India, the different aspects of aromatic rice, bacterial diseases of rice, quality control and breeding strategies, and much more. This volume is a useful reference for professionals and graduate students working in all areas of rice science and technology

Heavy metals in South African medicinal plants with refence to safety, efficacy and quality.

Ph. D. University of KwaZulu-Natal, Pietermaritzburg 2014.The trend in commercialization of medicinal plant products reflects the excessive exploitation of medicinal plants from the wild populations. Due to widespread soil pollution, there is a likelihood that medicinal plants could be harvested from heavy metal-contaminated soils and thus pose a potential health threat to consumers. Unregulated procurement coupled with the unhygienic trading environment, poor post-harvest handling and processing, represent major routes of heavy metal contamination in medicinal plant products. A comparative screening was carried out to assess the levels of heavy metal contamination in some frequently used South African medicinal plants obtained from out-door traditional medicinal markets and muthi shops. Plant samples were digested using a microwave-assisted acid digestion system and the elemental content determined using inductively coupled plasma optical emission spectrophotometry (ICP-OES). There was multi-elemental contamination in the investigated medicinal plants with elevated levels of Fe, Al and Mn detected in most of the samples and levels of As and Hg were above the World Health Organization limits of 1 mg kg-1 and 2 μg kg-1 respectively. The high levels of metal contaminations in some of the investigated medicinal plants is a health concern and urgent measures are needed to protect the health of consumers. Samples were quantified for their total phenolic and flavonoid contents as well as screened for antibacterial activity. Variable phenolic and flavonoid composition and antibacterial activity showed that the quality and efficacy of medicinal plants sold at traditional medicine markets is compromised. Data obtained from elemental analysis was subjected to hierarchical cluster analysis which categorized samples into four main groups with samples within a group having relatively similar metal analyte compositions. Hierarchical cluster analysis proved to be a valuable tool in this preliminary screening of heavy metal contamination in medicinal plants and can potentially be used to develop a large database for easy monitoring of plant species with hyperaccumulative potentials. Information such as site of collection, plant species and plant part could be a valuable approach to ensure safety, efficacy and quality of medicinal plants sold at traditional medicine markets. Exposure to Cd and Al for six weeks in a pot trial induced responses in Bulbine natalensis, Drimia elata and Hypoxis hemerocallidea and these included variations in heavy metal uptake, growth parameters and physiological changes. Generally, application of Cd and Al at low concentrations (2 and 500 mg L-1 respectively) enhanced growth parameters in the three plant species compared to the control plants. However, at the highest concentrations of Cd 10 and Al 1500 mg L-1 respectively, there was significant growth inhibition. Hypoxis hemerocallidea exhibited good tolerance to Al exposure up to 1000 mg L-1 compared to the other plant species. Some of the physiological changes such as accumulation of free-proline increased progressively with increasing heavy metal treatments in all the investigated plant species. The combined treatment of Cd 5:Al 1000 mg L-1 exhibited synergistic effects on the uptake and accumulation of Cd and Al with values of about 83 and 918 mg kg-1 respectively in the bulbs of D. elata. In B. natalensis, the combined treatment of Cd 10:Al 1500 mg L-1 resulted in the highest amount of Cd (67 mg kg-1) in the bulb samples while the highest amount of Al (1607 mg kg-1) was recorded after treatment with Cd 5:Al 1000 mg L-1. There was an antagonistic effect on the uptake and accumulation of Cd in H. hemerocallidea in the combined treatments. Energy dispersive X-ray analysis of the abaxial leaf surface indicated that more Al was translocated to the shoot in H. hemerocallidea compared to Cd. The bulbs and corms of the investigated medicinal plants are the most extensively utilized plant parts in traditional medicine. High levels of Cd and Al in the bulbs and corms raise public health concerns. Analysis of photosynthetic pigments showed total chlorophyll progressively decrease with increasing heavy metal stress in all three plant species. The effect of Cd and Al on chlorophyll fluorescence in H. hemerocallidea was investigated. Non-photochemical quenching (NPQ) was adversely affected in most of the heavy metal-treated plants indicating a photoinactivation of photosystem II (PSII) reaction centres. In the present study, increasing heavy metal treatment resulted in the inability of H. hemerocallidea to utilize the absorbed light energy leading to oxidative stress. Exposure to Cd and Al treatments for six weeks induced several ultrastructural changes in H. hemerocallidea including damage to the cortical cells and an increase in xylem size. Transmission electron microscopy revealed a complete breakdown of the thylakoids at the highest Cd treatment and the application of Al at moderate and the highest treatment significantly reduced the size of the chloroplasts. These ultrastructural changes could possibly explain the reduced chlorophyll fluorescence and the amounts of total chlorophyll recorded at the higher levels of heavy metal treatments. Biosynthesis and accumulation of secondary metabolites under heavy metal stress were variable in the investigated plants. The moderate Cd treatment at Cd 5 mg L-1 up-regulated the synthesis of total phenolics slightly compared to the controls in B. natalensis. All the other heavy metal treatments down-regulated the synthesis of total phenolics and flavonoids compared to the control plants in B. natalensis. Application of Cd and Al at the lowest concentrations, 2 and 500 mg L-1 respectively up-regulated the synthesis and accumulation of both phenolics and flavonoids in D. elata compared to the control plants. In H. hemerocallidea, the highest amounts of total phenolics and flavonoids were recorded at the moderate Cd treatment (5 mg L-1). High performance liquid chromatography showed a significant decrease in the levels of hypoxoside, a bioactive compound in H. hemerocallidea after heavy metal exposure. The lowest amount of hypoxoside was recorded at the highest concentration of the combined treatment (Cd 10:Al 1500 mg L-1). These variable responses to heavy metal stress indicated the need for in-depth research on changes of secondary metabolites in medicinal plants exposed to heavy metals in order to ensure ultimate quality and efficacy of medicinal plant products. There was a progressive decrease in antioxidant activity as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging in the bulb extracts of B. natalensis and D. elata. The lowest treatment of Al (500 mg L-1) had slightly higher DPPH activity compared to the positive control (ascorbic acid). Extracts of H. hemerocallidea exhibited a progressive increase in DPPH activity with increasing heavy metal treatments. There was a significant decrease in the DPPH activity at the highest Cd application (10 mg L-1) compared to the control plants indicating a loss in the biosynthesis of important bioactive compounds at high levels of heavy metal exposure. Cadmium applied at low and moderate concentrations enhanced antibacterial activity (0.78 mg mL-1) against Staphylococcus aureus in B. natalensis compared to the control plant extracts. However, there was poor antibacterial activity against Escherichia coli in all the heavy metal-treated plants in B. natalensis. Application of Cd and AL at low concentration in D. elata enhanced good antibacterial activity (0.78 mg mL-1) against E. coli which is less susceptible to antibiotics than S. aureus. Extracts from all Cd-treated plants as well as low and moderate Al-treated H. hemerocallidea plants exhibited the good antibacterial activity against S. aureus compared to the control plants. Plants treated with the combined Cd 2:Al 500 mg L-1 treatment also had good activity against S. aureus. However, all the extracts of H. hemerocallidea exhibited poor activity against E. coli. The responses of plants to Cd and Al varied depending on the species. Their ability to accumulate elevated levels of heavy metals raises concerns not only on the safety of these products but also the issues regarding the quality and efficacy of plants grown on heavy metal contaminated soils. The findings presented in this thesis highlight the need for stringent monitoring of heavy metal contamination in medicinal plant material sold at traditional medicine markets and the need for safe and sustainable cultivation of important medicinal plants. This will ensure that medicinal plant products are of a standard quality, safe from toxic contaminants and consistent in terms of phytochemical compositions

Plant Responses and Tolerance to Salt Stress: Physiological and Molecular Interventions

Overall, the 19 contributions in this Special Issue “Plant Responses and Tolerance to Salt Stress: Physiological and Molecular Interventions” discuss the various aspects of salt stress responses in plants. It also discusses various mechanisms and approaches to conferring salt tolerance on plants. These types of research studies provide further directions in the development of crop plants for the saline environment in the era of climate change

Effect of canopy position and non-detructive determination of rind biochemical properties of citrus fruit during postharvest non-chilling cold storage.

Doctor of Philosophy in Horticultural Science. University of KwaZulu-Natal, Pietermaritzburg, 2017.No abstract provided.This thesis is a compilation of manuscripts where each individual chapter is an independent article/manuscript introduced disjointedly

Detection of loci associated with water-soluble carbohydrate accumulation and environmental adaptation in white clover (Trifolium repens L.) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Biology at Massey University, Palmerston North, New Zealand

White clover (Trifolium repens L.) is an economically important forage legume in New Zealand/Aotearoa (NZ). It provides quality forage and a source of bioavailable nitrogen fixed through symbiosis with soil Rhizobium bacteria. This thesis investigated the genetic basis of two traits of significant agronomic interest in white clover. These were foliar water-soluble carbohydrate (WSC) accumulation and soil moisture deficit (SMD) tolerance. Previously generated divergent WSC lines of white clover were characterised for foliar WSC and leaf size. Significant (p < 0.05) divergence in foliar WSC content was observed between five breeding pools. Little correlation was observed between WSC and leaf size, indicating that breeding for increased WSC content could be achieved in large and small leaf size classes of white clover in as few as 2 – 3 generations. Genotyping by sequencing (GBS) data were obtained for 1,113 white clover individuals (approximately 47 individuals from each of 24 populations). Population structure was assessed using discriminant analysis of principal components (DAPC) and individuals were assigned to 11 genetic clusters. Divergent selection created a structure that differentiated high and low WSC populations. Outlier detection methodologies using PCAdapt, BayeScan and KGD-FST applied to the GBS data identified 33 SNPs in diverse gene families that discriminated high and low WSC populations. One SNP associated with the starch biosynthesis gene, glgC was identified in a genome-wide association study (GWAS) of 605 white clover individuals. Transcriptome and proteome analyses also provided evidence to suggest that high WSC levels in different breeding pools were achieved through sorting of allelic variants of carbohydrate metabolism pathway genes. Transcriptome and proteome analyses suggested 14 gene models from seven carbohydrate gene families (glgC, WAXY, glgA, glgB, BAM, AMY and ISA3) had responded to artificial selection. Patterns of SNP variation in the AMY, glgC and WAXY gene families separated low and high WSC individuals. Allelic variants in these gene families represent potential targets for assisted breeding of high WSC levels. Overall, multiple lines of evidence corroborate the importance of glgC for increasing foliar WSC accumulation in white clover. Soil moisture deficit (SMD) tolerance was investigated in naturalised populations of white clover collected from 17 sites representing contrasting SMD across the South Island/Te Waipounamu of NZ. Weak genetic differentiation of populations was detected in analyses of GBS data, with three genetic clusters identified by ADMIXTURE. Outlier detection and environmental association analyses identified 64 SNPs significantly (p < 0.05) associated with environmental variation. Mapping of these SNPs to the white clover reference genome, together with gene ontology analyses, suggested some SNPs were associated with genes involved in carbohydrate metabolism and root morphology. A common set of allelic variants in a subset of the populations from high SMD environments may also identify targets for selective breeding, but this variation needs further investigation