Cytokinin inhibition of Arabidopsis root growth: An examination of genotype, cytokinin activity, and N6-benzyladenine metabolism |
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Authors: | C A Auer |
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Institution: | (1) Department of Plant Science, University of Connecticut, 06269 Storrs, Connecticut, USA |
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Abstract: | The effects of cytokinins on the in vitro growth of the roots of Arabidopsis thaliana seedlings were examined. Root growth was inhibited in a manner dependent upon the type of cytokinin compound, the cytokinin concentration, the Arabidopsis genotype, and the duration of exposure to cytokinin. For the cytokinins N
6-benzyladenine (BA), isopentenyl adenine (iP), or dihydrozeatin (DHZ), the concentration required for 50% root growth inhibition differed for each cytokinin and in each of three Arabidopsis genotypes tested. iP was the most active cytokinin in inhibiting the root growth of the Ler-0 genotype, whereas iP and BA had equal activity when tested with the Col-2 and Columbia genotypes. DHZ had the lowest activity of the three cytokinins tested in all three genotypes. A brief 1-day exposure of seeds to a root-inhibiting concentration of BA increased root growth compared with seedlings grown without BA; exposure to BA for 3–6 days inhibited root growth. BA metabolism was evaluated after 6 h and 1, 3, and 6 days in Columbia seedlings. BA, N
6-benzyladenosine (BAR), and N
6-benzyladenosine-5-monophosphate (BAMP) decreased with time, whereas N
6-benzyladenine-7--d-glucopyranoside (BA-7-G) and N
6-benzyladenine-9--d-glucopyranoside (BA-9-G) accumulated in the growing seedlings. Seven aromatic cytokinins were compared at 5 m for their effect on Col-3 root growth. BA, BAR, N
6-(m-hydroxybenzylamino)adenine, and N
6-(o-hydroxybenzylamino)adenine were highly effective in inhibiting root growth, whereas N
6-(p-hydroxybenzylamino)adenine produced only a slight decrease in root growth. BA-7-G and BA-9-G did not affect root growth.Abbreviations BA
N
6-benzyladenine
- iP
isopentenyl-adenine
- DHZ
dihydrozeatin
- BAR
N
6-benzyladenosine
- BAMP
N
6-benzyladenosine 5-monophosphate
- BA-7-G
N
6-benzyladenine-7--d-glucopyranoside
- BA-9-G
N
6-benzyladenine-9--d-glucopyranoside
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m-OH BA
N
6-(m-hydroxybenzylamino)adenine
-
o-OH BA
N
6-(o-hydroxybenzylamino)adenine
-
p-OH BA
N
6-(p-hyrdoxybenzylamino)adenine
- HPLC
high performance liquid chromatography
- gFW
grams fresh weight |
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Keywords: | Cytokinin Metabolism Root growth |
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