Low_Mo_Arabidopsis_mapping_MOT1

ABSTRACT 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, establishes 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. Keywords: genomic hybridization bulked segregant analysis Overall design: Hybridizations from a set of Bulk Segregant analysis. An F2 population from 14501 in the col-0 background crossed to Ler-0 was analyzed. This series contains the 3 hybs from Ler used to identify Single Feature Polymorphisms, the 3 hybs of Col-0 they were compared to, and 1 hyb for each pool from the BSA mapping(High Mo pool, low Mo Pool).