Dissertation
Understanding the physiological importance of amino acid transport processes in legumes
Washington State University
Doctor of Philosophy (PhD), Washington State University
05/2010
DOI:
https://doi.org/10.7273/000006005
Abstract
Nitrogen is essential for plant growth and development, and amino acids represent the predominant N transport forms in most plants. Transporters are required to effectively move the organic N from cell to cell and over long distances. This research addresses the functions of amino acid transporters in legumes and their importance for whole-plant physiology and productivity. Novel amino acid transporters were identified in French bean (Phaseolus vulgaris), PvAAP1, and pea (Pisum sativum) PsAAP3, PsAAP6, and PsCAT6. Functional complementation in yeast demonstrated that, with the exception of PsCAT6, they are functional transporters and mediate the growth of yeast cells on a broad spectrum of amino acids. Furthermore, expression analyses in nodules, phloem, and seeds, as well as transporter localization to the plasma membrane suggest that the transporters are involved in cellular import processes throughout the plant and that their function is highly cell-specific. The role of PsAAP6 in nodules was further analyzed by repressing PsAAP6 expression and it was found that nodule amino acid levels and development are affected in the transgenic roots. Together, our analyses of transporter function in legumes demonstrate the importance of membrane proteins in movement of amino acids in nodules, over long distances, and in import into seeds. We further examined the role of amino acid transport in plant metabolism and productivity. Transgenic pea plants expressing a yeast transporter for Smethylmethionine, a nitrogen and sulfur containing amino acid, in the phloem were produced and analyzed. Results showed that nitrogen and sulfur phloem transport as well as metabolism were affected in the transgenic plants. In addition, changes in long distance transport of nitrogen and sulfur led to an increase in total seed production and in total seed S, N and protein yields. Overall, our results demonstrate that phloem transport of S-methylmethionine is important to seed quality and quantity.
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Details
- Title
- Understanding the physiological importance of amino acid transport processes in legumes
- Creators
- Qiumin Tan
- Contributors
- Mechthild Tegeder (Chair)Gerald E Edwards (Committee Member) - Washington State University, School of Biological SciencesSanja Roje (Committee Member) - Washington State University, Institute of Biological Chemistry
- Awarding Institution
- Washington State University
- Academic Unit
- School of Biological Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 185
- Identifiers
- 99901055028101842
- Language
- English
- Resource Type
- Dissertation