Novák O, Hényková E, Sairanen I, Kowalczyk M, Pospíšil T, Ljung K
Tissue specific profiling of the Arabidopsis thaliana auxin metabolome
Plant J. 2012 72(3):523-536

Abstract
The plant hormone auxin is believed to influence almost every aspect of plant growth and development. Auxin transport, biosynthesis and degradation combine to form gradients of the hormone that influence a range of key developmental and environmental response processes. There is abundant genetic evidence for the existence of multiple pathways for auxin biosynthesis and degradation. The complexity of these pathways makes it difficult to get a clear picture of the relative importance of specific metabolic pathways during development. We have developed a sensitive mass spectrometry-based method for simultaneously profiling the majority of known auxin precursors and conjugates/catabolites in small amounts of Arabidopsis tissue. The method includes a new derivatization technique for the quantification of the most labile of the auxin precursors. We validated the method by profiling the auxin metabolome in root and shoot tissues from different Arabidopsis thaliana ecotypes and auxin overproducing mutant lines. Substantial differences were shown in metabolite patterns between the different lines and tissues. We were also able to show differences of several orders of magnitude in the abundance of auxin metabolites, potentially indicating the relative importance of these compounds in the maintenance of auxin levels and activity. The method we have established will enable researchers to gain a better understanding of the dynamics of auxin metabolism and activity during plant growth and development.

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