Amino Acid Export in Developing Arabidopsis Seeds Depends on UmamiT Facilitators

Müller, Benedikt; Fastner, Astrid; Karmann, Julia; Mansch, Verena; Hoffmann, Thomas; Schwab, Wilfried; Suter Grotemeyer, Marianne; Rentsch, Doris; Truernit, Elisabeth; Ladwig, Friederike; Bleckmann, Andrea; Dresselhaus, Thomas; Hammes, Ulrich Z. (2015). Amino Acid Export in Developing Arabidopsis Seeds Depends on UmamiT Facilitators. Current Biology, 25(23), pp. 3126-3131. Cell Press 10.1016/j.cub.2015.10.038

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Essential amino acids cannot be synthesized by humans and animals. They often are limiting in plant-derived foods and determine the nutritional value of a given diet [1]. Seeds and fruits often represent the harvestable portion of plants. In order to improve the amino acid composition of these tissues, it is indispensable to understand how these substrates are transported within the plant. Amino acids result from nitrogen assimilation, which often occurs in leaves, the source tissue. They are transported via the vasculature, the xylem, and the phloem into the seeds, the so-called sink tissue, where they are stored or consumed. In seeds, several tissues are symplasmically isolated [2, 3], i.e., not connected by plasmodesmata, channels in the cell walls that enable a cytoplasmic continuum in plants [4]. Consequently, amino acids must be exported from cells into the apoplast and re-imported many times to support seed development. Several amino acid importers are known, but exporters remained elusive [5, 6]. Here, we characterize four members of the plant-specific UmamiT transporter family from Arabidopsis, related to the amino acid facilitator SIAR1 and the vacuolar auxin transporter WAT1 [7, 8]. We show that the proteins transport amino acids along their (electro)chemical potential across the plasma membrane. In seeds, they are found in tissues from which amino acids are exported. Loss-of-function mutants accumulate high levels of free amino acids in fruits and produce smaller seeds. Our results strongly suggest a crucial role for the UmamiTs in amino acid export and possibly a means to improve yield quality.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Molecular Plant Physiology
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)

UniBE Contributor:

Suter, Marianne and Rentsch, Doris


500 Science > 580 Plants (Botany)




Cell Press




Peter Alfred von Ballmoos-Haas

Date Deposited:

12 Jan 2016 14:21

Last Modified:

12 Jan 2016 14:21

Publisher DOI:





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