Alexein

Alexein is a historical term used in plant biology to denote antimicrobial compounds produced by plants in response to pathogen attack. In modern literature, the term is largely obsolete or used only in older texts; the class of substances it described is now usually referred to as phytoalexins, a term that emphasizes inducible defense metabolites.

These compounds are synthesized de novo at infection sites after exposure to pathogens and contribute to localized resistance. They are typically secondary metabolites derived from phenylpropanoid, isoprenoid, or allied biosynthetic pathways and tend to accumulate where the plant has been challenged.

Examples of well-characterized phytoalexins include camalexin (Arabidopsis thaliana), glyceollins (soybean), and resveratrol (grapevine). While these specific molecules may be cited today, the blanket term alexein is rarely used outside historical contexts; researchers generally refer to phytoalexins or to the specific compound name.

Significant research on alexein/phytoalexin pathways informs crop protection strategies and breeding programs aimed at disease resistance. Studies focus on elicitors that trigger production, regulatory networks controlling synthesis, and methods to enhance phytoalexin responses without harming plant growth.