Carotenoid Biosynthesis — a Target for Herbicide Activity

Carotenoids are chloroplast constituents. In vivo different carotenoids may be present at different sites within the chloroplast, and may have different functions. Especially important is a role in protecting the chloroplast and hence the p lant from chlorophyll-sensitized photooxidation. If carotenoid biosynthesis can be blocked by herbicides, such protection will no longer be afforded, and rapid death of the plant is likely. In this article current knowledge of carotenoid biosynthesis is reviewed. The main characteristics of each stage in the biosynthesis are outlined and the suit­ ability of these reactions as possible herbicide targets is assessed. Two experimental approaches to the study of the effects of herbicides on carotenoid biosynthesis are suggested.