Affiliation:
1. Plant Physiology, Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, D–72076 Tübingen, Germany (M.T., W.B.F.); and
2. Department of Biological Sciences, The University of Newcastle, Newcastle, New South Wales 2308, Australia (C.E.O., J.W.P.).
Abstract
Abstract
To determine the nature and cellular localization of amino acid transport in pea seeds, two cDNA clones belonging to the AAP family of H+/amino acid co-transporters (PsAAP1 and PsAAP2) were isolated from a cotyledon cDNA library of pea (Pisum sativum L.). Functional expression in the yeast amino acid uptake mutants 22Δ6AAL and 22Δ8AA showed that PsAAP1 mediates transport of neutral, acidic, and basic amino acids. RNA-blot analyses showed that PsAAP1 is expressed in seeds and vegetative organs, including amino acid sinks and sources, whereasPsAAP2 could not be detected. For developing seeds, transcripts of PsAAP1 were detected in coats and cotyledons, with seed coats giving a weak signal. In cotyledons, expression was highest in epidermal-transfer-cell-enriched tissue. RNA in situ hybridization analysis showed that PsAAP1 was predominantly present in epidermal transfer cells forming the outer surface of cotyledons, which abuts the seed coats. Overall, our observations suggest that this transporter, which is localized in transfer cells of cotyledons, might play a role in the uptake of the full spectrum of amino acids released from seed coats.
Publisher
Oxford University Press (OUP)
Subject
Plant Science,Genetics,Physiology
Cited by
104 articles.
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