title: Abscisic acid inhibits root growth in Arabidopsis through ethylene biosynthesis.
abstract: When first discovered in 1963, abscisic acid (ABA) was called abscisin II because it promotes abscission. Later, researchers found that ABA accelerates abscission via ethylene. In Arabidopsis, previous studies have shown that high concentrations of ABA inhibit root growth through ethylene signaling but not ethylene production. In the present study in Arabidopsis, we found that ABA inhibits root growth by promoting ethylene biosynthesis. The ethylene biosynthesis inhibitor L-α-(2-aminoethoxyvinyl)-glycine reduces ABA inhibition of root growth, and multiple mutants of ACS (1-aminocyclopropane-1-carboxylate synthase) are more resistant to ABA in terms of root growth than the wild-type is. Two ABA-activated calcium-dependent protein kinases, CPK4 and CPK11, phosphorylate the C-terminus of ACS6 and increase the stability of ACS6 in ethylene biosynthesis. Plants expressing an ACS6 mutant that mimics the phosphorylated form of ACS6 produce more ethylene than the wild-type. Our results reveal an important mechanism by which ABA promotes ethylene production. This mechanism may be highly conserved among higher plants.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
authors.forename: Xingju
authors.initials: X
authors.lastname: Luo
authors.forename: Zhizhong
authors.initials: Z
authors.lastname: Chen
authors.forename: Junping
authors.initials: J
authors.lastname: Gao
authors.forename: Zhizhong
authors.initials: Z
authors.lastname: Gong
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism*; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D018525:Germination; D008190:Lyases / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010766:Phosphorylation; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000235:genetics; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction
chemical_list: D000040:Abscisic Acid; D029681:Arabidopsis Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D005030:Ethylenes; D008190:Lyases; D010937:Plant Growth Regulators; D011494:Protein Kinases; C036216:ethylene; C508909:CPK11 protein, Arabidopsis; C000595436:CPK4 protein, Arabidopsis; C021773:1-aminocyclopropanecarboxylate synthase
keywords: ABA; Arabidopsis; calcium-dependent protein kinase; ethylene; root growth