Definition of phytoalexin in English:



  • A substance that is produced by plant tissues in response to contact with a parasite and specifically inhibits the growth of that parasite.

    • ‘Tryptophan is used in some plant species as a precursor to bioactive alkaloids and defence phytoalexins, as well as the phytohormone auxin.’
    • ‘Plant resistance to specific pathogens is often correlated with increased production of phytoalexins, whereas inhibition or deficiency of phytoalexin production allows greater virulence.’
    • ‘During infection by fungal pathogens, plant cells respond by expressing a battery of disease response genes, which can result in the production of various toxic plant products, including active oxygen species and phytoalexins.’
    • ‘These compounds represent the major forms of phytoalexins in grape.’
    • ‘Plants produce phytoalexins as an immune response to physical, chemical, or biological damage.’


1940s: from phyto- ‘of plants’ + alexin, a name for a class of substances found in blood serum, able to destroy bacteria.