Deleting A Gene Shuts Down Costly Fungus

By analyzing how the fungus Botrytis cinerea makes its signature plant-killing sesquiterpene toxins, an international team of scientists has offered hope for growers of vegetables, fruits, and ornamental plants that new ways may be found to disarm this costly plant pathogen (ACS Chem. Biol., DOI: 10.1021/cb800225v). B. cinerea is the culprit behind gray mold disease, which affects hundreds of agricultural and ornamental plants, including cash crops such as tomatoes, strawberries, and green beans. The fungus kills its plant prey by releasing a variety of phytotoxins, most notably botrydial and structurally related sesquiterpenes. Muriel Viaud of France's National Institute for Agricultural Research, in Versailles; David E. Cane of Brown University; Isidro G. Collado of the University of Cádiz, in Spain; and coworkers characterized the cluster of five genes responsible for the biosynthesis of these toxins. Deleting one of these genes, which encodes a sesquiterpene cyclase enzyme, shuts down production of the toxins. The researchers found that the enzyme converts farnesyl diphosphate to presilphiperfolan-8β-ol (shown, center), the parent sesquiterpene alcohol of botrydial and related toxins. Targeting this enzyme could lead to novel ways of combating gray mold disease.