Dokument: Post-submergence recovery of photosynthesis and growth: A comparison between two wetland plants
| Titel: | Post-submergence recovery of photosynthesis and growth: A comparison between two wetland plants | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=16831 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20101208-105015-6 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Dr. Fang-Li, Luo [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Schurr, Ulrich [Gutachter] Prof. Dr. Jahns, Peter [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 570 Biowissenschaften; Biologie | |||||||
| Beschreibung: | Flooding, including complete submergence as the most extreme case, is one of the common environmental challenges for plants in natural and artificial ecosystems. Recent studies, especially those in rice, have advanced our understanding of the regulatory mechanisms induced in plants during flooding. In comparison, recovery processes and responses upon de-submergence are not so well understood, even though plant performance during flood intervals is critical for their establishment in water-level-fluctuation zones.
In this PhD thesis, the behavior of two wetland species, Alternanthera philoxeroides and Hemarthria altissima, was studied during recovery following complete submergence. In an attempt to infer the strategies of submergence tolerance in these plants, I first checked the morphological and anatomical responses during submergence. Following de-submergence, changes in antioxidative defense, photosynthesis, carbohydrate partitioning and growth were closely analyzed both in shoots and roots. Additionally, low-light stress, instead of submergence stress, was applied to some plants to identify the responses and effects which are specifically induced by submergence (low light + low O2). Plants of A. philoxeroides were characterized by enhanced stem elongation, a typical feature of the escape strategy, and dramatic decrease in photosystem II activities upon submergence. Rapid stem elongation, together with the high porosity in shoots and roots, may improve light environment and O2 and CO2 availability of A. philoxeroides during submergence, while it leads to carbohydrate depletion when leaves fail to grow out of water. Following de-submergence, A. philoxeroides were able to quickly adjust the capacity of photosynthesis and antioxidative defense, which probably is crucial for growth recovery of this species. Plants of A. philoxeroides flexibly allocated the biomass to the organs for acquisition of most limiting resources, both during submergence (stems to gain light, O2 and CO2) and after de-submergence (leaves to gain carbohydrate). In contrast, submerged plants of H. altissima, having the quiescence strategy, exhibited neither stem elongation nor strong photosystem II downregulation but stored carbohydrate for a longer period. Unlike A. philoxeroides, leaves of H. altissima could maintain high antioxidant capacities, which may explain the lack of O2- and H2O2 detection under all conditions. Notably, carbohydrate (sucrose) stored in shoots was rapidly hydrolyzed and utilized to promote growth shortly after de-submergence. In contrast to A. philoxeroides, conservative biomass allocation to culms, a storage organ of this species, may be essential for H. altissima to survive future flooding. Based on these results, I propose that submergence tolerance of the escape and quiescence strategies entails not only the corresponding regulation of carbohydrate catabolism and energy metabolism during submergence but also coordinated regulation of antioxidative defense, photosynthesis, carbohydrate partitioning and growth following de-submergence. The findings shed a new light on submergence tolerance in plants and emphasize the importance to understand whole-plant responses to changing environments when considering stress tolerance. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Sonstige Einrichtungen/Externe » Institute in Zusammenarbeit mit der Heinrich-Heine-Universität Düsseldorf » Institut für Chemie und Dynamik der Geosphäre, Institut III. Phytosphäre, Forschungszentrum Jülich GmbH | |||||||
| Dokument erstellt am: | 08.12.2010 | |||||||
| Dateien geändert am: | 08.12.2010 | |||||||
| Promotionsantrag am: | 08.10.2010 | |||||||
| Datum der Promotion: | 30.11.2010 |
