Light-induced auxin-inhibiting substance from sunflower seedlings
1997
Yokotani-Tomita, K. | Kato, D (Dzhundzhi) | Kosemura, S. | Yamamura, S. | Kushima, M. | Kakuta, H. | Hasegawa, K.
A plant growth-inhibiting substance was isolated from deetiolated sunflower (Helianthus annuus) seedlings. Its structure was identified as 8-epixanthatin from IR, 1H NMR and EI mass spectra. 8-Epixanthatin was detected in sunflower and burweed shoots, but not in lettuce, radish, oat and corn. 8-Epixanthatin inhibited auxin-induced growth of sunflower hypocotyl and oat coleoptile sections at concentrations higher than 100 micromolar and 30 micromolar, respectively, and the elongation of cress roots at concentrations higher than 30 micromolar. However, it did not affect gibberellin-induced growth of lettuce hypocotyls and second leaf sheaths of rice at the various concentrations used. The light-grown seedlings were observed to contain a higher level of 8-epixanthatin than the dark control, and the difference in its level was noticeable before the growth inhibition by light appeared. These results suggest that 8-epixanthatin with its auxin-inhibiting activity might contribute to the light-induced growth inhibition of sunflower seedlings.
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