Variation in molybdenum content across broadly distributed populations of Arabidopsis thaliana is controlled by a mitochondrial molybdenum transporter (MOT1).
Molybdenum (Mo) is an essential micronutrient for plants, serving as a cofactor for enzymes involved in nitrate assimilation, sulfite detoxification, abscisic acid biosynthesis, and purine degradation. Here we show that natural variation in shoot Mo content across 92 Arabidopsis thaliana accessions is controlled by variation in a mitochondrially localized transporter (Molybdenum Transporter 1 - MOT1) that belongs to the sulfate transporter superfamily. A deletion in the MOT1 promoter is strongly associated with low shoot Mo, occurring in seven of the accessions with the lowest shoot content of Mo. Consistent with the low Mo phenotype, MOT1 expression in low Mo accessions is reduced. Reciprocal grafting experiments demonstrate that the roots of Ler-0 are responsible for the low Mo accumulation in shoot, and GUS localization demonstrates that MOT1 is expressed strongly in the roots. MOT1 contains an N-terminal mitochondrial targeting sequence and expression of MOT1 tagged with GFP in protoplasts and transgenic plants, establishing the mitochondrial localization of this protein. Furthermore, expression of MOT1 specifically enhances Mo accumulation in yeast by 5-fold, consistent with MOT1 functioning as a molybdate transporter. This work provides the first molecular insight into the processes that regulate Mo accumulation in plants and shows that novel loci can be detected by association mapping.
Baxter
Ivan
I
Bindley Bioscience Center, Purdue University, West Lafayette, Indiana, United States of America.
Muthukumar
Balasubramaniam
B
Park
Hyeong Cheol
HC
Buchner
Peter
P
Lahner
Brett
B
Danku
John
J
Zhao
Keyan
K
Lee
Joohyun
J
Hawkesford
Malcolm J
MJ
Guerinot
Mary Lou
ML
Salt
David E
DE
D000483:Alleles; D027321:Anion Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D017360:Arabidopsis / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D017353:Gene Deletion; D017343:Genes, Plant; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D008982:Molybdenum / Q000378:metabolism*; D010641:Phenotype; D018520:Plant Shoots / Q000378:metabolism; D030821:Plants, Genetically Modified; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
D027321:Anion Transport Proteins; D029681:Arabidopsis Proteins; D017931:DNA Primers; D018744:DNA, Plant; C525371:MOT1 protein, Arabidopsis; D011994:Recombinant Proteins; D008982:Molybdenum