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Chemistry and biology of phototropism‐regulating substances in higher plants
Author(s) -
Yamamura Shosuke,
Hasegawa Koji
Publication year - 2001
Publication title -
the chemical record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.61
H-Index - 78
eISSN - 1528-0691
pISSN - 1527-8999
DOI - 10.1002/tcr.1020
Subject(s) - phototropism , coleoptile , auxin , raphanus , hypocotyl , gravitropism , botany , helianthus , seedling , avena , shoot , chemistry , biology , biophysics , sunflower , blue light , horticulture , arabidopsis , physics , biochemistry , mutant , gene , optics
Most people are familiar with the sight of a young seedling bending towards a window or the brightest source of light to which it is exposed. This directional growth response is known as phototropism, which is caused by a lateral growth‐promoting auxin in the bending organ (Cholodny‐Went theory, cited in high school textbook). Recently, however, Bruinsma et al., Weiler et al., and Hasegawa et al. independently found that the shaded half did not contain more auxin than the illuminated one. Instead it was found that the even distribution of auxin was accompanied by a lateral gradient of growth inhibiting substances during phototropic curvature (Bruinsma‐Hasegawa theory). We have isolated some photo‐induced growth inhibitory substances related to phototropism, benzoxazolinones from light‐grown maize shoots ( Zea mays L.), raphanusanins from radish hypocotyl ( Raphanus sativus var. hortensis f. gigantissimus M.), indolyacetonitrile from light‐grown shoots ( Brassica oleacea L.), 8‐epixanthatin from sunflower hypocotyl ( Helianthus annus L.), and quite recently uridine from oat coleoptile ( Avena sativa L.). Chemical analyses have shown phototropic stimulations to cause curvature by inducing a local unequal distribution of growth‐inhibiting substances that antagonize auxin in its cell‐elongating activity. Finally, a model is presented for further studies on phototropism. © 2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:362–372, 2001