Natural Products and Their Potential in Agriculture

Abstract

Biologically active natural products are derived from three major sources: the fermentation of microorganisms, higher plants, and insects. However, compounds derived from these sources may act within each or all of these domains. That is, compounds derived from microorganisms and higher plants may affect insects and vice versa. Often, natural products are obtained in limited quantities and small yields do not lend themselves to extensive testing. During the past three years there has been increased synthesis of natural product templates and their analogs for evaluation in biological systems. Relative to these approaches, assorted natural products from microorganisms, including oligopeptides, acyclic polyketols and some relatively simple molecules are examined. The brassinosteroids and photodynamic herbicides, from higher plants, are discussed. Finally, compounds that are produced by insects, or which affect insects, are reviewed.In common with my primal ancestors, whose life began in a garden, my first recollections were not so much of people but of trees, flowers, the sun, rain, clouds, blue sky, and the sound of the cuckoo. Especially imprinted on my senses was the peppery smell of lupin at the early age of two, and there followed the scent of roses and English lavender: dire warnings about foxglove and deadly nightshade were issued as I wandered about gardens. An introduction to the world of secondary metabolites had started early in life and subsequently led to my first scientific job, in the mid

Antinutritive and toxic components of plant defense against insects

“…A wealth of literature on chemical identity, (suspected) cause and effect, and, to a much lesser degree, mechanism of action supports this evidence (Arnason et al, 1989;Barbosa et al, 1991;Berenbaum and Rosenthal, 1992;Brattsten and Ahmad, 1986;Cutler, 1988;Spencer, 1988). The impact of natural products upon the acquisition and utilization of food by arthropods has been grouped for convenience of classification, simplicity of communication, and/or knowl-edge of mechanisms of action, into several categories: digestibility reducers, toxins, nutrients, and modifiers of feeding behavior (Ahmad, 1983;Berenbaum and Rosenthal, 1992;Coley et al, 1985).…”

Allelopathy of Sage and White Wormwood on Purslane Germination and Seedling Growth

“…In most cases, these compounds inhibit the germination or growth of neighboring plants, although sometimes they may show a stimulating effect (Ebana et al, 1981). Inhibitory effects of allelophatic plants may be exploited within an integrated weed management system to modify crop-weed interactions and lower the need for chemical means of weed control; indeed, yield losses caused by weeds are well documented in many studies and it has been shown that these losses may frequently be higher than those caused by pests and diseases (Culter, 1988;Steinsiek et al, 1982).…”

High efficacy of extracts of Cameroon plants against tomato late blight disease

“…The application of crude plant extracts for the control of pests and diseases in crop production systems is standard practice in most developing countries (Cutler, 1988;Dales, 1996) and various organic extracts from these regions were reported to possess differing levels of antimicrobial activities in vitro and in vivo against phytopathogenic fungi and bacteria (Ameziane et al, 2007;Montes-Molina et al, 2008). The main advantages of using these compounds include their availability and a broad spectrum of modes of action (Winteringham, 1985;Cutler, 1988;Regnault-Roger et al, 2005). Studies examining different Solanaceous crops have reported that essential oils and plant extracts are effective growth inhibitors of P. infestans.…”