Alkylresorcinol biosynthesis in plants: new insights from an ancient enzyme family?

Alkylresorcinols are members of an extensive family of bioactive compounds referred to as phenolic lipids, which occur primarily in plants, fungi, and bacteria. In plants, alkylresorcinols and their derivatives are thought to serve important roles as phytoanticipins and allelochemicals, although direct evidence for this is still somewhat lacking. Specialized type III polyketide synthases (referred to as 'alkylresorcinol synthases'), which catalyze the formation of 5-alkylresorcinols using fatty acyl-CoA starter units and malonyl-CoA extender units, have been characterized from several microbial species, however until very recently little has been known concerning their plant counterparts. Through the use of sorghum and rice EST and genomic data sets, significant inroads have now been made in this regard. Here we provide additional information concerning our recent report on the identification and characterization of alkylresorcinol synthases from Sorghum bicolor and Oryza sativa, as well as a brief consideration of the emergence of this intriguing subfamily of enzymes.