Phototropism in Hypocotyls of Radish V. Lateral Distribution of cis- and trans-Raphanusanins and Raphanusamide in Various Phototropisms Induced by Unilateral Broad Blue Light

Abstract

Summary The first positive, the indifferent response, and the second positive phototropic curvatures in Raphanus sativus hypocotyls, induced by unilateral broad blue light (half band width 43 nm, λ max 448 nm), were shown to depend on the magnitude of growth suppression at the lighted sides of the hypocotyls. The growth inhibitors, cis - and trans -raphanusanins, increased at the lighted side in the first and second positive phototropic curvatures, but hardly in the region of indifference. The concentration at the dark side was similar to that in the dark control. Thus the unequal distribution of raphanusanins in the hypocotyls is closely correlated with different flank growth rates of the hypocotyls, while an increase of raphanusamide in the lighted sides was detected only in the second positive phototropic curvature. These results suggest that the first positive, the indifferent response and the second positive phototropic curvatures, induced by unilateral blue light, are mainly caused by the lateral distribution of cis - and trans -raphanusanins in the hypocotyls.