Arabidopsis ALS1 encodes a root tip and stele localized half type ABC transporter required for root growth in an aluminum toxic environment

• Published in: Planta 2007-05, Vol.225 (6), p.1447-1458, Article 1447
• Main Authors: Larsen, Paul B., Cancel, Jesse, Rounds, Megan, Ochoa, Vanessa
• Format: Article
• Language: English
• Subjects: ABC transporter; ABC transporters; Acidic soils; Agronomy. Soil science and plant productions; Alleles; Aluminum; Aluminum - toxicity; Amino Acid Sequence; Amino acid substitution; Amino acids; Arabidopsis; Arabidopsis - drug effects; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; ATP binding cassette transporters; ATP-Binding Cassette Transporters - chemistry; ATP-Binding Cassette Transporters - genetics; ATP-Binding Cassette Transporters - metabolism; Biological and medical sciences; Chromosome Mapping; Cloning; Cloning, Molecular; Crop production; Economic plant physiology; Fundamental and applied biological sciences. Psychology; Gels; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes; Genetic mutation; Hypersensitivity; Molecular Sequence Data; Mutants; Mutation; Organs; Phenotypes; Plant growth; Plant Leaves - metabolism; Plant roots; Plant Roots - drug effects; Plant Roots - growth & development; Plant Roots - metabolism; Plants; RNA; Root growth; Root tips; Roots; Seedlings; Substrates; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); Toxicity; Transporter
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-006-0452-4

Aluminum toxicity in acid soils severely limits crop productivity through inhibition of root growth and, consequently, shoot development. Several Arabidopsis mutants were previously identified as having roots with Al hypersensitivity, suggesting that these represent deleterious mutations affecting genes required for either Al tolerance or resistance mechanisms. For this report, the als1-1 mutant was chosen for further characterization. The phenotype of als1-1 is most obviously presented in Al challenged roots, as evidenced by exaggerated root growth inhibition in conjunction with increased expression of Al-responsive genes compared to wt. Using a map-based cloning approach, the als1-1 mutation was isolated and found to represent a deleterious amino acid substitution in a previously uncharacterized half type ABC transporter, At5g39040, which is expressed in a non-Al dependent manner in all organs tested. GUS-dependent analyses revealed that ALS1 expression is primarily localized to the root tip and the vasculature throughout the plant. Concomitant with this, an ALS1: GFP fusion accumulates at the vacuolar membrane of root cells, indicating that ALS1 may be important for intracellular movement of some substrate, possibly chelated Al, as part of a mechanism of Al sequestration.