Secondary metabolites as sources of bioherbicides: present situation and perspectives

Abstract

Secondary metabolites produced and released by plants, bacteria, and fungi are involved in a number of ecological processes, namely as semiochemicals and allelopathins. In addition, and beside their possible ecological roles, a greater number of secondary metabolites are phytotoxic and represent a relatively unexplored source of new herbicides.

Solanum nigrum (black nightshade) is an important and successful weed in many crops, namely in horticulture, and will be used as a major example of actual and prospective uses of phytoallelochemicals as bioherbicides.

Therefore, the main strategies for bioherbicides search are reviewed and the state of art of the modes of action of allelochemicals is presented, including those already in use as herbicides (Bialaphos and PPT), patented (AAL-toxin), and under investigation, whether produced by plants (sorgoleone and cineol derivatives), bacteria (hydantocidin) or fungi (fumonisins and colletotrichin).