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Amino acid uptake in Arabidopsis

the transporters involved, kinetics of uptake and growth on amino acids

Svennerstam, Henrik (2008). Amino acid uptake in Arabidopsis. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2008:50
ISBN 987-91-85913-83-1
[Doctoral thesis]

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Abstract

Nitrogen (N) is essential for all living organisms and is considered to be the limiting factor for plant growth in many ecosystems. Although generally believed to rely on mineral N to fulfill their N needs, plants have also been found to access organic N such as amino acids. Despite extensive research, the importance of amino acids as N sources for plants still remains unclear. The work presented in this thesis has focused on identifying the transporters responsible for amino acid uptake in plants and to characterize mutants lacking these transporters. Two transporters important for Arabidopsis thaliana amino acid uptake were identified, the lysine histidine transporter 1 (LHT1) and amino acid permease 5 (AAP5). These two transporters were found to have complementary, non-overlapping affinity spectra, i.e. LHT1 displayed affinity for neutral- and acidic amino acids and for L-Histidine, whereas AAP5 exhibited affinity for L-Arginine and L-Lysine only. Mutants lacking both LHT1 and AAP5 were found to have little residual uptake of the amino acids tested, suggesting these transporters to be the most important for Arabidopsis root amino acid uptake. Mutants lacking LHT1 or AAP5 displayed much reduced uptake rates in the low !M range suggesting these transporters mediate efficient uptake at field relevant concentrations. LHT1 mutants did not only have impaired uptake capacity, but also grew less than wild type when grown on for example L-Glutamine as the sole N source. In contrast, by over-expressing LHT1, plants grew larger on amino acids, suggesting a connection between uptake capacity and growth. Growth experiments using labeled amino acids in a mixture with nitrate revealed that a substantial amount of plant N was amino acid derived, suggesting that Arabidopsis has the ability to efficiently use amino acids as a source of N. The results presented in this thesis provide a mechanistic understanding to the process of root amino acid uptake in plants. This knowledge is important for future research within the field of plant organic N nutrition and Arabidopsis genotypes with altered amino acid uptake capacities can be used as tools to further elucidate the ecological benefit plants may have by taking up amino acids.

Authors/Creators:Svennerstam, Henrik
Title:Amino acid uptake in Arabidopsis
Subtitle:the transporters involved, kinetics of uptake and growth on amino acids
Year of publishing :2008
Volume:2008:50
Number of Pages:44
Papers/manuscripts:
NumberReferences
ALLI Svennerstam, H., Ganeteg, U., Bellini, C. & Näsholm, T. (2007). Comprehensive Screening of Arabidopsis Mutants Suggests the Lysine Histidine Transporter 1 to Be Involved in Plant Uptake of Amino Acids. Plant Physiology 143: 1853-1860. II Svennerstam, H., Ganeteg, U. & Näsholm, T. (2008). Root uptake of cationic amino acids by Arabidopsis depends on functional expression of Amino Acid Permease 5. New Phytologist, published online. III Svennerstam, H., Jämtgård, S., Huss-Danell, K., Ganeteg, U. & Näsholm, T. Root amino acid uptake in Arabidopsis (manuscript). IV Forsum, O., Svennerstam, H., Ganeteg, U. & Näsholm T. (2008). Capacities and constratinsts of amino acid utilization in Arabidopsis. New Phytologist, published online.
Place of Publication:Umeå
ISBN for printed version:987-91-85913-83-1
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:arabidopsis thaliana, nitrogen, amino acids, nutrient uptake, growth
Keywords:Arabidopsis thaliana, LHT1, AAP5, nitrogen, amino acid, uptake, knockout, transporter.
URN:NBN:urn:nbn:se:slu:epsilon-2463
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-2463
ID Code:1794
Department:(S) > Dept. of Forest Genetics and Plant Physiology
Deposited By: Henrik Svennerstam
Deposited On:25 Aug 2008 00:00
Metadata Last Modified:02 Dec 2014 10:14

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