Phytoalexins are low molecular weight antimicrobial compounds that are produced by plants as
a response to biotic and abiotic stresses. As such they take part in an intricate defense system which
enables plants to control invading microorganisms. In the 1950s, research on phytoalexins started
with progress in their biochemistry and bio-organic chemistry, resulting in the determination of their
structure, their biological activity, as well as mechanisms of their synthesis and catabolism by
microorganisms. Elucidation of the biosynthesis of numerous phytoalexins also permitted the use of
molecular biology tools for the exploration of the genes encoding enzymes of their synthesis
pathways and their regulators. This has led to potential applications for increasing plant resistance to
diseases. Phytoalexins display an enormous diversity belonging to various chemical families such as
for instance, phenolics, terpenoids, furanoacetylenes, steroid glycoalkaloids, sulfur-containing
compounds and indoles.
Research and review papers dealing with numerous aspects of phytoalexins including modulation
of their biosynthesis, molecular engineering in plants, biological activities, structure/activity
relationships and phytoalexin metabolism by micro-organisms are published in this issue.