A type III ACC synthase, ACS7, is involved in root gravitropism in Arabidopsis thaliana.
Ethylene is an important plant hormone that regulates developmental processes in plants. The ethylene biosynthesis pathway is a highly regulated process at both the transcriptional and post-translational level. The transcriptional regulation of these ethylene biosynthesis genes is well known. However, post-translational modifications of the key ethylene biosynthesis enzyme 1-aminocyclopropane-1-carboxylate (ACC) synthase (ACS) are little understood. In vitro kinase assays were conducted on the type III ACS, AtACS7, fusion protein and peptides to determine whether the AtACS7 protein can be phosphorylated by calcium-dependent protein kinase (CDPK). AtACS7 was phosphorylated at Ser216, Thr296, and Ser299 by AtCDPK16 in vitro. To investigate further the function of the ACS7 gene in Arabidopsis, an acs7-1 loss-of-function mutant was isolated. The acs7-1 mutant exhibited less sensitivity to the inhibition of root gravitropism by treatment with the calcium chelator ethylene glycol tetraacetic acid (EGTA). Seedlings were treated with gradient concentrations of ACC. The results showed that a certain concentration of ethylene enhanced the gravity response. Moreover, the acs7-1 mutant was less sensitive to inhibition of the gravity response by treatment with the auxin polar transport inhibitor 1-naphthylphthalamic acid, but exogenous ACC application recovered root gravitropism. Altogether, the results indicate that AtACS7 is involved in root gravitropism in a calcium-dependent manner in Arabidopsis.
Institute of Plant Biology, National Taiwan University, Taipei, Taiwan.
Shih-Jhe
SJ
Huang
Chia-Lun
CL
Chang
Po-Hsun
PH
Wang
Min-Chieh
MC
Tsai
Pang-Hung
PH
Hsu
Ing-Feng
IF
Chang
D048948:14-3-3 Proteins / Q000378:metabolism; D000595:Amino Acid Sequence; D000598:Amino Acids, Cyclic / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D005030:Ethylenes / Q000494:pharmacology; D005453:Fluorescence; D006112:Gravitation; D018522:Gravitropism / Q000187:drug effects; D018021:Lithium Chloride / Q000494:pharmacology; D008190:Lyases / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology*; D025941:Protein Interaction Mapping; D011494:Protein Kinases / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D058525:Quartz Crystal Microbalance Techniques; D015203:Reproducibility of Results; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology; D017871:Calcium-Calmodulin-Dependent Protein Kinases
D048948:14-3-3 Proteins; D000598:Amino Acids, Cyclic; D002118:Calcium; D002614:Chelating Agents; D005030:Ethylenes; D018021:Lithium Chloride; D008190:Lyases; D010455:Peptides; D011494:Protein Kinases; D025841:Small Ubiquitin-Related Modifier Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C023863:1-aminocyclopropane-1-carboxylic acid; C036216:ethylene; C021773:1-aminocyclopropanecarboxylate synthase
14-3-3; ACS; CDPK; calcium; ethylene; phosphorylation; root gravitropism.