Selenate-resistant mutants of Arabidopsis thaliana identify Sultr1;2, a sulfate transporter required for efficient transport of sulfate into roots.
To investigate how plants acquire and assimilate sulfur from their environment, we isolated and characterized two mutants of Arabidopsis thaliana deficient in sulfate transport. The mutants are resistant to selenate, a toxic analogue of sulfate. They are allelic to each other and to the previously isolated sel1 (selenate-resistant) mutants, and have been designated sel1-8 and sel1-9. Root elongation in these mutants is less sensitive to selenate than in wild-type plants. Sulfate uptake into the roots is impaired in the mutants under both sulfur-sufficient and sulfur-deficient conditions, but transport of sulfate to the shoot is not affected. The sel1 mutants contain lesions in the sulfate transporter gene Sultr1;2 located on the lower arm of chromosome 1. The sel1-1, sel1-3 and sel1-8 mutants contain point mutations in the coding sequences of Sultr1;2, while the sel1-9 mutant has a T-DNA insertion in the Sultr1;2 promoter. The Sultr1;2 cDNA derived from wild-type plants is able to complement Saccharomyces cerevisiae mutants defective in sulfate transport, but the Sultr1;2 cDNA from sel1-8 is not. The Sultr1;2 gene is expressed mainly in roots, and accumulation of transcripts increases during sulfate deprivation. Examination of transgenic plants containing the Sultr1;2 promoter fused to the GUS-reporter gene indicates that Sultr1;2 is expressed mainly in the root cortex, the root tip and lateral roots. Weaker expression of the reporter gene was observed in hydathodes, guard cells and auxiliary buds of leaves, and in anthers and the basal parts of flowers. The results indicate that Sultr1;2 is primarily involved in importing sulfate from the environment into the root.
Shibagaki
Nakako
N
Department of Botany, Iowa State University, Ames, Iowa 50011, USA.
Rose
Alan
A
McDermott
Jeffrey P
JP
Fujiwara
Toru
T
Hayashi
Hiroaki
H
Yoneyama
Tadakatsu
T
Davies
John P
JP
D000483:Alleles; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002874:Chromosome Mapping; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D005816:Genetic Complementation Test; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins; D010641:Phenotype; D018517:Plant Roots / Q000235:genetics* / Q000502:physiology; D017354:Point Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics; D064586:Selenic Acid; D018036:Selenium Compounds / Q000378:metabolism*; D000076988:Sulfate Transporters; D013431:Sulfates / Q000378:metabolism*; D013455:Sulfur / Q000172:deficiency / Q000378:metabolism / Q000494:pharmacology
D002352:Carrier Proteins; D018076:DNA, Complementary; D026901:Membrane Transport Proteins; C085609:SLC26A4 protein, human; D018036:Selenium Compounds; D000076988:Sulfate Transporters; D013431:Sulfates; D013455:Sulfur; D005966:Glucuronidase; D064586:Selenic Acid