Root-growth Inhibition by DL-Homocysteine Thiolactone and Its Related Compounds

Abstract

DL-Homocysteine thiolactone hydrochloride showed growth inhibition toward the roots of Brassica campestris L. subsp. rapa HooK. fil. et ANDERS, Lactuca sativa L. var. longifolia LAM, and Echinochloa utilis 0HWI et YABUNO even at the low concentration of 5.0 × 10^-5 M. This inhibitory activity is higher than that of dihydro-2(3H)-thiophenone reported previously. On the other hand, the N-acetyl and N-benzoyl derivatives of DL-homocysteine thiolactone exhibited much less activity. These facts suggest that the free amino group at C-3 in DL-homocysteine thiolactone is essential to enhanced inhibitory activity. The amounts of chlorophyll in the cotyledons of B. campestris treated with DL-homocysteine thiolactone were decreased when compared with the control.