Abscisic acid regulates root elongation through the activities of auxin and ethylene in Arabidopsis thaliana.
Abscisic acid (ABA) regulates many aspects of plant growth and development, including inhibition of root elongation and seed germination. We performed an ABA resistance screen to identify factors required for ABA response in root elongation inhibition. We identified two classes of Arabidopsis thaliana AR mutants that displayed ABA-resistant root elongation: those that displayed resistance to ABA in both root elongation and seed germination and those that displayed resistance to ABA in root elongation but not in seed germination. We used PCR-based genotyping to identify a mutation in ABA INSENSITIVE2 (ABI2), positional information to identify mutations in AUXIN RESISTANT1 (AUX1) and ETHYLENE INSENSITIVE2 (EIN2), and whole genome sequencing to identify mutations in AUX1, AUXIN RESISTANT4 (AXR4), and ETHYLENE INSENSITIVE ROOT1/PIN-FORMED2 (EIR1/PIN2). Identification of auxin and ethylene response mutants among our isolates suggested that auxin and ethylene responsiveness were required for ABA inhibition of root elongation. To further our understanding of auxin/ethylene/ABA crosstalk, we examined ABA responsiveness of double mutants of ethylene overproducer1 (eto1) or ein2 combined with auxin-resistant mutants and found that auxin and ethylene likely operate in a linear pathway to affect ABA-responsive inhibition of root elongation, whereas these two hormones likely act independently to affect ABA-responsive inhibition of seed germination.
Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130.
Julie M
JM
Thole
Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005.
Erin R
ER
Beisner
Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005.
James
J
Liu
Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005.
Savina V
SV
Venkova
Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130 strader@wustl.edu.
Lucia C
LC
Strader
D000040:Abscisic Acid / Q000494:pharmacology*; D000483:Alleles; D017360:Arabidopsis / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002874:Chromosome Mapping; D005030:Ethylenes / Q000378:metabolism*; D005838:Genotype; D059014:High-Throughput Nucleotide Sequencing; D007210:Indoleacetic Acids / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D017422:Sequence Analysis, DNA
C100794:AUX1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D005030:Ethylenes; D007210:Indoleacetic Acids; D000040:Abscisic Acid; C036216:ethylene
epistasis; mutant screen; plant hormones; whole genome sequencing