title: A comparison of sulfate and selenium accumulation in relation to the expression of sulfate transporter genes in Astragalus species.
abstract: Sulfate and selenate uptake were investigated in both selenium (Se) hyperaccumulators (Astragalus racemosus and Astragalus bisulcatus) and closely related nonaccumulator species (Astragalus glycyphyllos and Astragalus drummondii). Sulfur (S) starvation increased Se accumulation, whereas increased selenate supply increased sulfate accumulation in both root and shoot tissues. cDNAs for homologs of groups 1 to 4 sulfate transporters were cloned from these Astragalus species to investigate patterns of expression and interactions with sulfate and selenate uptake. In contrast to all other previously analyzed plant species, abundant gene expression of putative sulfate transporters was observed for both Se-hyperaccumulating and nonaccumulating Astragalus, regardless of S and Se status. Furthermore, quantitative analysis of expression indicated a transcript level in Se-hyperaccumulating Astragalus comparable with other plant species under S deprivation. The high expression of sulfate transporters in certain Astragalus species may lead to enhanced Se uptake and translocation ability and therefore may contribute to the Se hyperaccumulation trait; however, it is not sufficient to explain S/Se discriminatory mechanisms.
authors.affiliation: Plant Science Department, Rothamsted Research, Harpenden AL5 2JQ, UK.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Cabannes
authors.forename: Peter
authors.initials: P
authors.lastname: Buchner
authors.forename: Martin R
authors.initials: MR
authors.lastname: Broadley
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: Hawkesford
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism*; D027883:Astragalus Plant / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D012313:RNA / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D064586:Selenic Acid / Q000032:analysis / Q000378:metabolism*; D012643:Selenium / Q000378:metabolism*; D016415:Sequence Alignment; D013431:Sulfates / Q000032:analysis / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism*
chemical_list: D027321:Anion Transport Proteins; D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; D018749:RNA, Plant; D013431:Sulfates; D012313:RNA; D013455:Sulfur; D012643:Selenium; D064586:Selenic Acid