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Phytochemical trafficking in Arabidopsis cells

Plants produce a very large number of specialized compounds that must be transported from their site of synthesis to the sites of storage or disposal. Anthocyanin accumulation has provided a powerful system to elucidate the molecular and cellular mechanisms associated with the intracellular trafficking of phytochemicals. We recently showed (Poustka et al; 2007) that Arabidopsis anthocyanin are transported to the vacuole trough vesicle-like structures shared with components of the secretory pathway and in a Golgi-independent manner. We hypothesis that two mechanisms for anthocyanin cellular transport, one involving transporters and one involving vesicles, coexist in a plant cell or might be both part of a common trafficking pathway.

Moreover, evidences from the literature show that flavonoid final products or intermediates can act as signal molecule and alter cellular processes such as auxin transport, nodulation or pollen tube growth (Pourcel and Grotewold, 2008). One of the lab projects is to find molecular players induced or repressed by the presence of flavonoid in Arabidopsis cells, by an integrated approach of metabolic and transcriptomic profiling.

 

DIC light micrographs of the lemma from male flowers of a B-I Pl plant. (photo from Niloufer Irani).

Anthocyanic vacuolar inclusions in isolated vacuoles from PAP1-D plants. From Poutska et al., 2007

Co-localization of anthocyanins with GFP-Chi labeled vesicles Epidermal cells show numerous small GFP-CHI labeled vesicles (A, C), anthocyanin red fluorescence in the central vacuole (B, C) which co-localized with GFP fluorescence in the GFP-Chi vesicles (B and C, marked with arrow). From Poutska et al., 2007.

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