Abstract
Fluoren-9-carboxylic acid acts not only as an auxin but also as an gibberellin-antagonist. In the standard pea straight test (S5 section) for auxin it stimulated elongation, the optimum concentration being 10 mg/l. On the other hand, it inhibited elongation at 0.1 mg/l. This inhibitory effect was more marked when younger tissue (S1 section) which also responds to gibberellin was used. Interaction of FCA and IAA in the S5 section has shown that at higher concentration of IAA there seemed to be a suppraoptimal effect, indicating that FCA acted as an auxin. However, in the S1 section, the stimulating effect of GA3 was markedly inhibited by 0.1 mg/l FCA; 10 mg/l FCA was either additive or less than additive to GA3. In the cucumber hypocotyl test FCA itself was inactive up to 100 μg/plant, but it inhibited the GA3-induced elongation. This inhibition was overcome by increasing the dosage of GA3. In the same material, the IAA-induced elongation was not affected by FCA. These results indicate that whether FCA acts as an auxin or a gibberellin-antagonist depends on whether the tissue is sensitive to gibberellin and/or auxin.
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Abbreviations
- FCA:
-
fluoren-9-carboxylic acid
- IAA:
-
indole-3-acetic acid
- GA3 :
-
gibberellin A3
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Katsumi, M. The mode of action of a morphactin, fluoren-9-carboxylic acid. Bot Mag Tokyo 86, 267–273 (1973). https://doi.org/10.1007/BF02488782
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DOI: https://doi.org/10.1007/BF02488782