Shikimate pathway

Definition

The shikimate pathway is a biochemical route that plants, bacteria, and fungi use to synthesize aromatic amino acids such as phenylalanine, tyrosine, and tryptophan from simple carbohydrates. This pathway is crucial for the production of secondary metabolites, which play key roles in plant defense, signaling, and interactions with other organisms.

5 Must Know Facts For Your Next Test

1. The shikimate pathway consists of seven enzymatic steps that convert phosphoenolpyruvate (PEP) and erythrose-4-phosphate into chorismate.
2. This pathway is vital for synthesizing three essential amino acids: phenylalanine, tyrosine, and tryptophan, which are precursors for many secondary metabolites like flavonoids and alkaloids.
3. Many herbicides target the shikimate pathway in plants and microorganisms because animals do not possess this pathway, making it a selective target for pest control.
4. The first step of the shikimate pathway is catalyzed by the enzyme 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAHPS), which is key to regulating the pathway's flow.
5. Secondary metabolites produced through the shikimate pathway contribute to plant defense mechanisms against pathogens and herbivores, showcasing their ecological importance.

Review Questions

• How does the shikimate pathway contribute to the production of secondary metabolites in plants?
  • The shikimate pathway is integral to the biosynthesis of aromatic amino acids that serve as precursors for a variety of secondary metabolites. These compounds include flavonoids, alkaloids, and phenolics, which play significant roles in plant defense against herbivores and pathogens. By producing these metabolites through the shikimate pathway, plants enhance their survival and adaptability in diverse environments.
• Evaluate the significance of targeting the shikimate pathway in agricultural practices, particularly in herbicide development.
  • Targeting the shikimate pathway has significant implications for agricultural practices because it provides a mechanism to selectively control weed populations without harming animals or humans. Herbicides that inhibit enzymes in this pathway can effectively kill plants that rely on it for aromatic amino acid synthesis. This selectivity makes it an attractive option for pest control, although it also raises concerns about potential environmental impacts and resistance development in target species.
• Analyze the broader ecological impact of the shikimate pathway in relation to plant interactions with their environment.
  • The shikimate pathway not only plays a critical role in synthesizing essential amino acids but also has far-reaching ecological impacts. The secondary metabolites produced through this pathway can influence plant-pollinator interactions by affecting flower color and scent or deterring herbivores through toxic compounds. Additionally, these metabolites can mediate plant interactions with microbial communities in the soil, promoting beneficial relationships that enhance nutrient uptake and soil health. Therefore, understanding this pathway helps clarify how plants adapt to their environments and maintain ecosystem balance.

Related terms

Aromatic amino acids: Essential amino acids that contain an aromatic ring in their structure, critical for protein synthesis and metabolic processes.

Secondary metabolites: Organic compounds produced by plants that are not directly involved in growth, development, or reproduction but serve important ecological functions.

Chorismate: A key intermediate in the shikimate pathway that is a precursor to various aromatic compounds, including vitamins and phytohormones.