The second Phytophthora mating hormone defines interspecies biosynthetic crosstalk

The heterothallic species of the agricultural pest Phytophthora use mating hormones alpha 1 and alpha 2 to regulate their sexual reproduction. Here we describe the absolute stereostructure of the second mating hormone alpha 2 as defined by spectroscopic analysis and total synthesis. We have uncovered not only the interspecies universality of alpha hormones but also the pathway by which alpha 2 is biosynthesized from phytol by A2-mating type strains and metabolized to alpha 1 by A1 strains.