The auxin signal for protoplast swelling is perceived by extracellular ABP1.
Protoplasts of corn coleoptiles and Arabidopsis hypocotyls respond to the plant hormone auxin with a rapid change in volume. We checked the effect of antibodies directed against epitopes of auxin-binding protein 1 from Arabidopsis thaliana (AtERabp1) and Zea mays (ZmERabp1), respectively. Antibodies raised against the C-terminus of AtERabp1 inhibited the response to auxin, while antibodies raised against a part of box a, the putative auxin-binding domain, induced a swelling response similar to that caused by auxin treatment. Synthetic C-terminal oligopeptides of ZmERabp1 also caused a swelling response. These effects occurred regardless of whether the experiments were carried out with homologous (anti-AtERabp1 antibodies on Arabidopsis protoplasts or anti-ZmERabp1 antibodies in maize protoplasts) or heterologous immunological tools. The results indicate that the auxin signal for protoplast swelling is perceived by extracellular ABP1.
Steffens
B
B
Institut für Allgemeine Botanik, Ohnhorststr. 18, 22609 Hamburg, Germany.
Feckler
C
C
Palme
K
K
Christian
M
M
Böttger
M
M
Lüthen
H
H
D000595:Amino Acid Sequence; D000918:Antibody Specificity; D017360:Arabidopsis / Q000166:cytology; D048429:Cell Size / Q000187:drug effects; D018548:Cotyledon / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D018546:Hypocotyl / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology; D010940:Plant Proteins / Q000276:immunology / Q000378:metabolism*; D011523:Protoplasts / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction; D013045:Species Specificity; D003313:Zea mays / Q000166:cytology
D007210:Indoleacetic Acids; D010446:Peptide Fragments; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C083846:auxin-binding protein 1; C030737:indoleacetic acid