Root uptake of cationic amino acids by Arabidopsis depends on functional expression of amino acid permease 5.
* Specific transporters mediate uptake of amino acids by plant roots. Earlier studies have indicated that the lysine histidine transporter 1 and amino acid permease 1 participate in this process, but although plant roots have been shown to absorb cationic amino acids with high affinity, neither of these transporters seems to mediate transport of L-arginine (L-Arg) or L-lysine (L-Lys). * Here, a collection of T-DNA knockout mutants were screened for alterations in Arabidopsis root uptake rates of L-Arg and it was found that only the AAP5 mutant displayed clear phenotypic divergence on high concentrations of L-Arg. A second screen using low concentrations of (15)N-labelled L-Arg in the growth media also identified AAP5 as being involved in L-Arg acquisition. * Momentaneous root uptake of basic amino acids was strongly affected in AAP5 mutant lines, but their uptake of other types of amino acids was only marginally affected. Comparisons of the root uptake characteristics of AAP5 and LHT1 mutants corroborated the hypothesis that the two transporters have distinct affinity spectra in planta. * Root uptake of all tested amino acids, except L-aspartic acid (L-Asp), was significantly affected in double AAP5*LHT1 mutants, suggesting that these two transporters account for a major proportion of roots' uptake of amino acids at low concentrations.
Svennerstam
Henrik
H
Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, SE-901 83 Umeå.
Ganeteg
Ulrika
U
Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, SE-901 83 Umeå.
Näsholm
Torgny
T
Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, SE-901 83 Umeå.|Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå.
D026923:Amino Acid Transport Systems, Basic / Q000235:genetics / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001120:Arginine / Q000378:metabolism; D001692:Biological Transport / Q000235:genetics; D015870:Gene Expression; D005973:Glutamine; D016254:Mutagenesis, Insertional; D009566:Nitrates / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism*
C420585:AAP5 protein, Arabidopsis; D026923:Amino Acid Transport Systems, Basic; D000596:Amino Acids; D029681:Arabidopsis Proteins; C110638:LHT1 protein, Arabidopsis; D009566:Nitrates; D005973:Glutamine; D001120:Arginine