Tabtoxin

Tabtoxin

Tabtoxin is a bacterial toxin produced by the plant-pathogenic bacterium Pseudomonas syringae. It is a phytotoxin that plays a significant role in the development of bacterial blight in various plant species, particularly in tobacco and soybean plants.

Structure and Biosynthesis

Tabtoxin is a dipeptide consisting of threonine and tabtoxinine-β-lactam. The biosynthesis of tabtoxin involves several enzymatic steps within Pseudomonas syringae. The genes responsible for its production are located within a specific gene cluster in the bacterial genome.

Mechanism of Action

Tabtoxin exerts its toxic effects by inhibiting the enzyme glutamine synthetase, which is crucial for the synthesis of glutamine from glutamate and ammonia. This inhibition leads to the accumulation of toxic levels of ammonia in the plant cells, causing chlorosis and necrosis of the plant tissues.

Role in Plant Pathogenesis

The production of tabtoxin by Pseudomonas syringae is a key factor in the development of bacterial blight. The toxin facilitates the spread of the bacterium within the plant by weakening the plant's defense mechanisms and causing cell death. This allows the bacterium to colonize the plant more effectively.

Host Range

Tabtoxin-producing strains of Pseudomonas syringae primarily infect tobacco and soybean plants, but they can also affect other plant species. The susceptibility of different plants to tabtoxin varies, with some plants showing more resistance than others.

Research and Applications

Research on tabtoxin has provided insights into the molecular mechanisms of plant-pathogen interactions and the role of bacterial toxins in plant diseases. Understanding the biosynthesis and mode of action of tabtoxin can help in developing strategies to control bacterial blight and improve plant resistance.

Related Pages

• Pseudomonas syringae
• Phytotoxin
• Bacterial blight
• Glutamine synthetase
• Chlorosis
• Necrosis