Phytoalexin

They are defined not by their having any particular chemical structure or character, but by the fact that they are defensively synthesized de novo by plants that produce the compounds rapidly at sites of pathogen infection.

Phytoalexins tend to fall into several chemical classes, including terpenoids, glycosteroids, and alkaloids; however, the term applies to any phytochemicals that are induced by microbial infection.

Mutants incapable of phytoalexin production exhibit more extensive pathogen colonization as compared to wild types.

[citation needed] As part of the induced resistance, the short-term response, the plant deploys reactive oxygen species such as superoxide and hydrogen peroxide to kill invading cells.

The reception of the signal leads to global changes within the plant, which induce expression of genes that protect from further pathogen intrusion, including enzymes involved in the production of phytoalexins.

Often, if jasmonates or ethylene (both gaseous hormones) are released from the wounded tissue, neighboring plants also manufacture phytoalexins in response.

[4] Allixin showed an anti-tumor promoting effect in vivo, inhibiting skin tumor formation by TPA in DMBA initiated mice.

[citation needed] Polyphenols, especially isoflavonoids and related substances, play a role in the plant defense against fungal and other microbial pathogens.