Coronatine

Coronatine structure

Coronatine is a phytotoxin produced by certain strains of the plant pathogen Pseudomonas syringae. It is a molecular mimic of the plant hormone jasmonic acid, which plays a crucial role in plant defense mechanisms. Coronatine is known to manipulate plant signaling pathways, leading to increased susceptibility to bacterial infection.

Structure and Biosynthesis

Coronatine is a polyketide compound composed of two distinct moieties: coronafacic acid (CFA) and coronamic acid (CMA). These two components are synthesized separately and then joined by an amide bond. The biosynthesis of coronatine involves a complex pathway that includes several enzymes and genes encoded by the coronatine biosynthetic gene cluster.

Mechanism of Action

Coronatine functions by mimicking jasmonic acid, thereby activating the jasmonate signaling pathway in plants. This activation leads to the suppression of the salicylic acid-mediated defense response, which is crucial for resistance against bacterial pathogens. By hijacking the plant's defense mechanisms, coronatine facilitates the spread and colonization of Pseudomonas syringae.

Role in Plant Pathogenicity

The production of coronatine is a key virulence factor for Pseudomonas syringae. It enhances the pathogen's ability to infect and cause disease in a wide range of host plants, including important agricultural crops such as tomato, Arabidopsis thaliana, and citrus. The presence of coronatine leads to symptoms such as chlorosis, necrosis, and the formation of water-soaked lesions on infected plants.

Research and Applications

Understanding the role of coronatine in plant-pathogen interactions has significant implications for agriculture and plant biology. Research on coronatine can lead to the development of new strategies for disease management and the breeding of resistant plant varieties. Additionally, coronatine and its analogs are used as tools in plant physiology research to study the jasmonate signaling pathway.

Related Pages

• Pseudomonas syringae
• Jasmonic acid
• Plant defense mechanisms
• Phytotoxin
• Polyketide
• Salicylic acid

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