| Abstract Detail
Metabolism Buerstenbinder, Katharina [1], Sauter, Margret [2]. Regulation of the methionine cycle in plants. S-adenosylmethionine is an activated form of methionine (Met) that serves as substrate for the biosynthesis of polyamines, phytosiderophores and ethylene. As a by-product, 5-methylthioadenosine (MTA) is released and subsequently recycled to Met via the Met cycle. We identified genes encoding Met cycle enzymes and proved their enzymatic activity. We showed that the Met cycle gene OsARD1 from rice was upregulated upon submergence or ethylene treatment. By contrast, Met cycle genes in Arabidopsis thaliana were not regulated by ethylene. Furthermore, limited sulfur supply or different sulfur sources did not influence Met cycle gene expression in Arabidopsis, whereas enzyme activity of an MTA-nucleosidase was induced by its substrate MTA and also, to a lesser extent, by Met. We hypothesize that regulation of Met cycle genes by ethylene may be restricted to plants with natural phases of high and prolonged ethylene synthesis such as climacteric fruits or semiaquatic plants and that regulation of the Met cycle occurs at both, the transcriptional and posttranscriptional level. Met cycle knock-out mutants in Arabidopsis showed phenotypic differences depending on the reaction at which the Met cycle was interrupted. When conversion from MTA to methylthioribose was interrupted in the Atmtn mutant, flower development was disfunctional/delayed. Knock-out of methylthioribose kinase was without effect on growth and development under sulfur-sufficient conditions. These data support the idea that accumulation or depletion of intermediates or products of the Met cycle rather than Met supply affected plant development at sulfur-replete conditions in the Atmtn mutant. We hypothesize that altered Met cycle metabolites may affect polyamine levels and subsequently plant development.
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1 - Botanical Institute, University of Kiel, Department of Developmental Biology and Physiology of Plants, Am Botanischen Garten 1-9, Kiel, 24118, Germany
2 - Botanical Institute, University of Kiel, Department of Developmental Biology and Physiology of Plants
Keywords:
methionine cycle
sulfur metabolism
ethylene synthesis
S-adenosylmethionine
Arabidopsis thaliana.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P19004
Abstract ID:158 |
