Phytotoxins plant pathogens

STROBEL ET AL. Phytotoxins from Plant Pathogens of Weedy Plants... 

Many AB strains produce secondary metabolites that are inhibitory to plants, including phytotoxins and antibiotics, which can be considered allelopathic. Phytotoxins from fluorescent Pseudomonas spp., a diverse group of plant pathogenic bacteria abundant in the soil and rhizosphere, have been well studied (Mitchell, 1991). There are fewer reports on phytotoxins from AB and many have not been extensively studied. 

JD Walton. Peptide phytotoxins from plant-pathogenic fungi. In H Kleinkauf, H von Dohren, eds. Biochemistry of Peptide Antibiotics. Berlin W. de Gruyter, 1990, pp 179-203. 

Some plant pathogenic bacteria and their phytotoxins have been screened in bioassays that monitor the effects of their toxins (antibiotic and phytotoxic) on other sensitive bacteria. For example, several fluorescent Pseudomonas syringae pvs. produce extracellular phytotoxins.76,106,116 Tabtoxin is produced by P. syringae pv. tabaci and pv. coronafacines, and this natural product inhibits glutamine synthetase.34,46,116 Phaseolotoxin, produced by P. syringae pv. phaseolicola... 

Microbes (plant pathogens) and microbial products (phytotoxins) have been shown to have potential as weed control agents. Growth in the interest in these alternative weed control methods has been brought about by a need for less persistent, more selective, and more environmentally safe herbicides. Broad-spectrum and selective activity are concepts important to the development of a weed control agent. 

Many new microbial compounds with potential blocherbicldal activity have been Isolated, chemically characterized, and a portion of their biological activities determined using various bioassay techniques or by direct plant screening. Some of these compounds are virulence factors of plant pathogens, thus Information on these phytotoxins can benefit the development of microbes as herbicides and potentially provide new chemical herbicides. Data on some of these compounds and their structures are presented. Information on source, biological activity, and possible mode of action (when available) Is briefly summarized. 

Each weed species is a host to an array of plant pathogenic fungi and bacteria. Many of these organisms induce disease symptoms by virtue of phytotoxin production (1). By focusing on these plant pathogens and on their phytotoxins we hope to find novel, environmentally compatible, host-selective chemical agents for weed control. 

The fungus Botrytis cinerea—a serious plant pathogen (Chapter 8)— produces a group of sesquiterpenoid fungal metabolites known as the botryanes. Botrydial (5.38), which is the major phytotoxin, and dihydrobotrydial (5.39) were first isolated in 1974. Their structures were established by X-ray crystallography. 

Phytotoxins produced by microbial plant pathogens, R.N. Strange, Nat. Prod. Rep., 2007, 24, 127. 

Miyagawa H, Nagai S, Tsurushima T, Sato M, Ueno T, Fukami H (1994) Phytotoxins Produced by the Plant Pathogenic Fungus Bipolaris bicolor Ei-1. Biosci Biotech Biochem 58 1143. 

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