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A new theory of phototropism – its regulation by a light‐induced gradient of auxin‐inhibiting substances
Author(s) -
Bruinsma Johan,
Hasegawa Koji
Publication year - 1990
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1990.tb00047.x
Subject(s) - phototropism , auxin , coleoptile , hypocotyl , biophysics , concentration gradient , curvature , chemistry , botany , biology , physics , biochemistry , blue light , chromatography , geometry , optics , mathematics , gene
Against the wholly indirect evidence of a lateral gradient of auxin as an explanation of phototropic curvature according to the Cholodny‐Went theory, direct measurement of free. extractable or diffusable indoleacetic acid from phototropically curving hypocotyls and coleoptiles invariably shows an even distribution of auxin. On the contrary, growth inhibitors extracted or diffused from these organs turn out to be accumulated at the irradiated side, as proposed already by A. H. Blaauw (Z. Bot. 7: 465. 1915). the classical experiment by F. W. Went (Rec. Trav. Bot. Neerl. 25:1, 1928) has to be interpreted as evidence for a lateral gradient of substance(s) inhibiting auxin activity Phototropic curvature is thus a matter of differential auxin sensitivity across the unilaterally irradiated organ.

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