title: Identification of a Dolabellane Type Diterpene Synthase and other Root-Expressed Diterpene Synthases inArabidopsis.
abstract: Arabidopsis thalianamaintains a complex metabolism for the production of secondary or specialized metabolites. Such metabolites include volatile and semivolatile terpenes, which have been associated with direct and indirect defensive activities in flowers and leaves. In comparison, the structural diversity and function of terpenes inArabidopsisroots has remained largely unexplored despite a substantial number of root-expressed genes in theArabidopsisterpene synthase (TPS) gene family. We show that five root-expressedTPSsof an expanded subfamily-a type clade in theArabidopsis TPSfamily function as class I diterpene synthases that predominantly convert geranylgeranyl diphosphate (GGPP) to different semi-volatile diterpene products, which are in part detectable at low levels in the ecotypes Columbia (Col) and Cape Verde Island (Cvi). The enzyme TPS20 produces a macrocyclic dolabellane diterpene alcohol and a dolabellane-related diterpene olefin named dolathaliatriene with a so far unknown C6-C11 bicyclic scaffold besides several minor olefin products. The TPS20 compounds occur in all tissues of Cvi but are absent in the Col ecotype because of deletion and substitution mutations in the Col TPS20 sequence. The primary TPS20 diterpene products retard the growth of the root rot pathogenPythium irregularebut only at concentrations exceeding thosein planta. Together, our results demonstrate that divergence and pseudogenization in theArabidopsis TPSgene family allow for structural plasticity in diterpene profiles of above- and belowground tissues.
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg VA, USA.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames IA, USA.
authors.forename: Meirong
authors.initials: M
authors.lastname: Jia
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg VA, USA.
authors.forename: Jung-Hyun
authors.initials: JH
authors.lastname: Huh
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg VA, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Muchlinski
authors.affiliation: Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames IA, USA.
authors.forename: Reuben J
authors.initials: RJ
authors.lastname: Peters
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg VA, USA.
authors.forename: Dorothea
authors.initials: D
authors.lastname: Tholl
keywords: Arabidopsis; diterpenes; ecotype; root; terpene synthase