Studies Into the Molecular Genetics of Alkaloid Synthesis in the Genus Nicotiana

Studies Into the Molecular Genetics of Alkaloid Synthesis in the Genus Nicotiana
Author: Kathleen D. DeBoer
Publisher:
Total Pages: 506
Release: 2010
Genre: Nicotiana
ISBN:

Two versions of the QPT gene were isolated (NgQPT1 and NgQPT2) from the genomic library of N. glauca. Both genes are highly homologous throughout their coding regions, and appear capable of encoding full length QPT proteins. However, they contain markedly divergent 5' regulatory regions and intronic regions. NgQPT2 seems to be the predominant transcript in both leaves and roots of N. glauca plants, with the proportion of the NgQPT2 transcript in the total QPT transcript pool, appearing to increase in both tissues in response to apex removal. Fusion of 2.4 kb from the NgQPT2 5' regulatory region to uidA, and transfer into hairy roots and transgenic plants, showed the promoter to be responsive to jasmonate. However, it appears to lack the necessary elements that confer responsiveness to apex removal and leaf based expression in transgenic N. glauca plants. The AP-2 transcription factors, NtORC1 and NtJAP1, which have previously been shown to activate the Nicotiana sylvestris putrescine N-methyltransferase (PMT) promoter (De Sutter et al., 2005), were tested for their ability to activate the N. glauca QPT2 promoter. Using a tobacco cell protoplast transient assay system, NtORC1, but not NtJAP1, was shown to activate the NgQPT2 promoter. The endogenous QPT transcript was also shown to accumulate in N. glauca hairy root lines overexpressing the NtORC1 gene. Previous studies have indicated that the ODC enzyme from Nicotiana glutinosa can decarbonxylate both ornithine and lysine (Lee and Cho, 2001a). To determine whether this enzyme is involved in the synthesis of anabasine in N. glauca, ODC transcript levels were down-regulated by RNAi technology in N. glauca hairy root cultures. ODC transcript down-regulation had very little effect upon anabasine levels, although a decrease in nicotine concentration was observed in many lines. This suggests that lysine decarboxylation, leading to cadaverine and anabasine synthesis, occurs via a different enzyme in this species. As a point of comparison, ODC transcript levels were also down-regulated in N. tabacum hairy root cultures, with a marked decrease in nicotine, and a concurrent increase in anatabine concentrations being observed in a number of lines. One copy of the A622 gene was isolated from the genome of N. glauca. At the onset of this study, a functional role for A622 in alkaloid biosynthesis had not been established. To examine the role of A622 in anabasine biosynthesis, transcript levels were down-regulated in N. glauca plants, via RNAi technology. A substantial reduction in anabasine levels was observed in transgenic plants and their offspring containing the RNAi construct. These results confirm an important role for the A622 enzyme in the synthesis of anabasine in N. glauca. This aspect of the current study has been published recently (DeBoer et al., 2009)

Plant Toxins

Plant Toxins
Author: P. Gopalakrishnakone
Publisher:
Total Pages:
Release:
Genre: Plant toxins
ISBN: 9789400767287

Salicylic Acid Signalling in Plants

Salicylic Acid Signalling in Plants
Author: Gabriella Szalai
Publisher: MDPI
Total Pages: 208
Release: 2020-12-28
Genre: Science
ISBN: 3039289810

Although the role of salicylic acid (SA) in plant physiological processes has been widely studied for a long time, many open questions remain several fields. The importance of SA synthesis is illustrated by the four review papers published in this Special Issue that represent a wide range of approaches, indicating that a growing body of evidence needs to be summarized in a thought-provoking manner. The investigations presented in the six original studies extend upon the understanding of the involvement of SA in anthracnose infection and light-dependent cold acclimation, highlighting the use of SA mutant Arabidopsis plants. The studies also focused on the application of novel SA analogs or SA in combination with Rhizobacteria inoculation. We hope that the four reviews and six studies provide a deeper understanding of the role of SA and its complex tasks, as well as a new direction for research to address gaps and open questions, including both at the metabolite and gene expression levels, in the use of agriculturally important crop or mutant model plants, and in both basic research and practical applications.

Nicotine Psychopharmacology

Nicotine Psychopharmacology
Author: Jack E. Henningfield
Publisher: Springer Science & Business Media
Total Pages: 545
Release: 2009-02-01
Genre: Medical
ISBN: 3540692487

The fact that tobacco ingestion can affect how people feel and think has been known for millennia, placing the plant among those used spiritually, honori?cally, and habitually (Corti 1931; Wilbert 1987). However, the conclusion that nicotine - counted for many of these psychopharmacological effects did not emerge until the nineteenth century (Langley 1905). This was elegantly described by Lewin in 1931 as follows: “The decisive factor in the effects of tobacco, desired or undesired, is nicotine. . . ”(Lewin 1998). The use of nicotine as a pharmacological probe to und- stand physiological functioning at the dawn of the twentieth century was a landmark in the birth of modern neuropharmacology (Limbird 2004; Halliwell 2007), and led the pioneering researcher John Langley to conclude that there must exist some “- ceptive substance” to explain the diverse actions of various substances, including nicotine, when applied to muscle tissue (Langley 1905). Research on tobacco and nicotine progressed throughout the twentieth century, but much of this was from a general pharmacological and toxicological rather than a psychopharmacological perspective (Larson et al. 1961). There was some attention to the effects related to addiction, such as euphoria (Johnston 1941), tolerance (Lewin 1931), and withdrawal (Finnegan et al. 1945), but outside of research supported by the tobacco industry, addiction and psychopharmacology were not major foci for research (Slade et al. 1995; Hurt and Robertson 1998; Henning?eld et al. 2006; Henning?eld and Hartel 1999; Larson et al. 1961).

Medicinal, Aromatic and Stimulant Plants

Medicinal, Aromatic and Stimulant Plants
Author: Johannes Novak
Publisher: Springer
Total Pages: 0
Release: 2020-10-10
Genre: Science
ISBN: 9783030387914

The agricultural sector of medicinal (including plant stimulants) and aromatic plants is characterized by an enormous number and diversity of species. Only a few of them can be considered cultivated crops in which significant breeding efforts are made. For most species, however, breeding is performed in short-term projects only. Therefore, basic knowledge about these species is still fragmentary. Our intention is to compile and organize the available information on the most commonly utilized plant species into one publication, thereby providing a standardized resource for the researchers and the grower community. This book therefore provides reference source materials for a wide variety of plant species used for human consumption due to their flavor, medicinal or recreational properties. It is divided into a section of general topics on genetic resources, breeding adaptation of analytic methods and a compilation of basic data for DNA content, chromosome number and mating system followed by a section of 20 monographs on a species or species groups.

Metabolic Engineering of Plant Secondary Metabolism

Metabolic Engineering of Plant Secondary Metabolism
Author: R. Verpoorte
Publisher: Springer Science & Business Media
Total Pages: 288
Release: 2013-03-09
Genre: Science
ISBN: 9401594236

Plant secondary metabolism is an economically important source of fine chemicals, such as drugs, insecticides, dyes, flavours, and fragrances. Moreover, important traits of plants such as taste, flavour, smell, colour, or resistance against pests and diseases are also related to secondary metabolites. The genetic modification of plants is feasible nowadays. What does the possibility of engineering plant secondary metabolite pathways mean? In this book, firstly a general introduction is given on plant secondary metabolism, followed by an overview of the possible approaches that could be used to alter secondary metabolite pathways. In a series of chapters from various authorities in the field, an overview is given of the state of the art for important groups of secondary metabolites. No books have been published on this topic so far. This book will thus be a unique source of information for all those involved with plants as chemical factories of fine chemicals and those involved with the quality of food and ornamental plants. It will be useful in teaching graduate courses in the field of metabolic engineering in plants.

Biochemistry and Molecular Biology of Plants

Biochemistry and Molecular Biology of Plants
Author: Bob B. Buchanan
Publisher: John Wiley & Sons
Total Pages: 1280
Release: 2015-08-31
Genre: Science
ISBN: 0470714220

With over 1000 original drawings and 500 photographs, this work offers complete coverage of cell biology, plant physiology and molecular biology.

Alkaloid Biology and Metabolism in Plants

Alkaloid Biology and Metabolism in Plants
Author: G. Waller
Publisher: Springer Science & Business Media
Total Pages: 302
Release: 2012-12-06
Genre: Science
ISBN: 1468407724

* This book is designed for the use of the advanced student and professional worker interested in the international scientific community, particularly those in the fields of agronomy, agricultural sciences, botany, biological sciences, natural products chemistry, pharmaceutical chemistry and bio chemistry. The purpose is to inform the reader about significant advances in the biology and metabolism of alkaloids in plants. Since alkaloids are generally referred to as "secondary metabolites," the reactions discussed are not, for the most part, involved with the main metabolic pathways. The reactions that we are interested in are pathways that have been developed for the formation of these secondary metabolites, using as their starting mole cules one of the compounds produced via a main or primary metabolic path way. The primary metabolic pathways are common to all plants, indeed to most living organisms, whereas the highly specialized branches leading to alkaloid formation are found in only about 10 to 20 % of the known plants. The reason for these diversities in plant metabolism is not clear; however, it seems likely that the formation of highly individualized and specialized pathways resulted as a response to the pressure of natural selection. Nevertheless, the genetic peculiarity that controls alkaloid production has provided many extremely interesting problems for scientists and consti tutes convincing evidence of nature's superior ability in biochemistry.

Secondary Plant Products

Secondary Plant Products
Author: E. E. Conn
Publisher: Academic Press
Total Pages: 819
Release: 2013-10-22
Genre: Science
ISBN: 1483289222

Approx.798 pages