Dokument: Regulation of crassulacean acid metabolism (CAM) in the facultative CAM species Talinum triangulare
| Titel: | Regulation of crassulacean acid metabolism (CAM) in the facultative CAM species Talinum triangulare | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=54486 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20201029-112601-9 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Maleckova, Eva [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Weber, Andreas P. M. [Betreuer/Doktorvater] Prof. Dr. Zurbriggen, Matias [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 570 Biowissenschaften; Biologie | |||||||
| Beschreibung: | Agriculture of the 21st century faces challenges in form of growing global population, increasing demands for food, feed and plant-based products, ongoing climate changes with more frequent and more severe drought periods, and shrinking arable land. To satisfy the production demands, plants relying on crassulacean acid metabolism (CAM) are an attractive alternative to C3 and C4 crops that require extensive irrigation. In parallel to increased reliance on CAM plants, CAM engineering (i.e. introduction of the CAM pathway to conventional crops) is a promising strategy to generate crops better suited to warmer and drier conditions. CAM is an extremely plastic adaptation, including facultative CAM - a reversible induction of the CAM pathway in C3 or rarely C4 species. Facultative CAM species are an excellent system to dissect the genetic components of CAM, mechanisms of their regulation and to shed more light on the evolutionary trajectories of CAM. Talinum triangulare is one of many facultative CAM species, with well described drought-inducible CAM and first ‘-omics’ resources available. The present thesis aims to establish T. triangulare as a model species for the field of CAM research. Even though water withdrawal induces CAM within few days in T. triangulare, the timing and nature of the initial signalling events leading to CAM induction are not known. Moreover, the onset of CAM induction depends on external variables, such as soil moisture and air humidity. Following up on the findings from the drought experiment performed previously, the phytohormone abscisic acid (ABA) was applied as a foliar spray. The effect of the treatment was studied by the means of RNA-sequencing and metabolite measurements, revealing the rapid pace and extent of ABA-induced transcriptional changes. These were moreover accompanied by altered levels of several metabolites and most importantly titratable acidity at the end of the dark. Several candidate transcription factors were identified as possible mediators of the CAM induction based on their transcriptional responsiveness. An unexpected finding was pronounced and rapid protein degradation following the ABA treatment. It was hypothesized that degradation of proteins with activities competing with the CAM cycle is an essential to CAM induction alongside with synthetic processes (Manuscript I).
Draft genome assembly and reference transcriptome were generated with long read sequencing technologies. Temporal adjustment of gene expression likely gained on importance in CAM species and promoter sequences of T. triangulare were therefore analysed for presence of known transcription factor binding sites. Motifs associated with ABA response and the circadian clock were enriched among genes sharing similar expression profiles during CAM induction. Interspecies comparison identified several putative transcription factor binding sites enriched in promoters of T. triangulare but not in C3 and obligate CAM species. Furthermore, protein-coding sequences were examined. Candidate genes shared by facultative CAM species, which included several putative transcription factors, an ABC transporter, and an ABA-inducible protein, were identified in an interspecies comparison. Examination of predicted protein sequences of phosphoenolpyruvate carboxylase responsible for nocturnal CO2 fixation revealed considerable diversity among isoforms of T. triangulare as well as across species. Further investigations of CAM regulation and evolution should embrace much of the diversity of CAM species and focus on both protein-coding sequences and regulatory elements (Manuscript II). | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Biologie » Biochemie der Pflanzen | |||||||
| Dokument erstellt am: | 29.10.2020 | |||||||
| Dateien geändert am: | 29.10.2020 | |||||||
| Promotionsantrag am: | 02.06.2020 | |||||||
| Datum der Promotion: | 29.07.2020 |
