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A Role for the TOC Complex in Arabidopsis Root Gravitropism
- Source :
- Plant Physiology. 149:1896-1905
- Publication Year :
- 2009
- Publisher :
- Oxford University Press (OUP), 2009.
-
Abstract
- Arabidopsis (Arabidopsis thaliana) roots perceive gravity and reorient their growth accordingly. Starch-dense amyloplasts within the columella cells of the root cap are important for gravitropism, and starchless mutants such as pgm1 display an attenuated response to gravistimulation. The altered response to gravity1 (arg1) mutant is known to be involved with the early phases of gravity signal transduction. arg1 responds slowly to gravistimulation and is in a genetically distinct pathway from pgm1, as pgm1 mutants enhance the gravitropic defect of arg1. arg1 seeds were mutagenized with ethylmethane sulfonate to identify new mutants that enhance the gravitropic defect of arg1. Two modifier of arg1 mutants (mar1 and mar2) grow in random directions only when arg1 is present, do not affect phototropism, and respond like the wild type to application of phytohormones. Both have mutations affecting different components of the Translocon of Outer Membrane of Chloroplasts (TOC) complex. mar1 possesses a mutation in the TOC75-III gene; mar2 possesses a mutation in the TOC132 gene. Overexpression of TOC132 rescues the random growth phenotype of mar2 arg1 roots. Root cap amyloplasts in mar2 arg1 appear ultrastructurally normal. They saltate like the wild type and sediment at wild-type rates upon gravistimulation. These data point to a role for the plastidic TOC complex in gravity signal transduction within the statocytes.
- Subjects :
- Toc complex
Genotype
Physiology
Molecular Sequence Data
Gravitropism
Arabidopsis
Plant Science
Genes, Plant
Models, Biological
Plant Roots
complex mixtures
Genetics
Arabidopsis thaliana
Amyloplast
Amino Acid Sequence
Plastids
Root cap
Alleles
Phototropism
Statocyte
biology
Arabidopsis Proteins
Starch
biology.organism_classification
Hypocotyl
Cell biology
Phenotype
Plant Root Cap
Mutagenesis
Multiprotein Complexes
Mutation
Gravitation
Signal Transduction
Research Article
Subjects
Details
- ISSN :
- 15322548
- Volume :
- 149
- Database :
- OpenAIRE
- Journal :
- Plant Physiology
- Accession number :
- edsair.doi.dedup.....fe5a1c93eaf4495fa0ef96f41e754a26