Tianfeng Xia

Title:    Influences of ascorbate and glutathione on root growth of poplar

Plants are anchored in the soil with their root system. Nutrients and water for plant growth and development are taken up from the soil water and distributed within the plant by long-distance transport systems. Environmental changes like a reduction of nutrients or water availability require adaptation processes to maintain plant growth, development and reproduction. It has been described that root growth increased during nutrient deficiency. In addition, reactive oxygen species (ROS) were established to interact with cell proliferation and elongation in the root system. ROS can be detoxified via the Foyer-Halliwell cycle (glutathione-ascorbate cycle) that includes the antioxidants glutathione (GSH) and ascorbate as substrates. Several studies demonstrated that both compounds influence root growth, although independently and by different mechanisms. An interaction between glutathione and ascorbate in root growth and development has not been established. Analyses of glutathione and ascorbate actions in roots are complicated by the fact that both compounds can be produced in roots in situ, but can also be delivered to the roots by long-distance transport in the phloem. The project is aimed to characterize the individual and interactive influence of root GSH and ascorbate levels on root growth and development. Therefore, transgenic poplar plants manipulated to achieve either modified ascorbate or GSH contents in the roots will be investigated. In addition, the project is aimed to study the dependency of root ascorbate and glutathione on its long-distance transport from the shoot. Although first investigations support the assumption that GSH and ascorbate contents, especially in root tips, depend on its supply from the shoot, further evidences are necessary to differentiate between roots in situ synthesis and the shoot supply to the roots.


Supervisors:      Heinz Rennenberg, Cornelia Herschbach


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