Abstract

Compounds of the terpenoid class play numerous roles in the interactions of plants with their environment, such as attracting pollinators and defending the plant against pests. We show here that the genome of cultivated tomato (Solanum lycopersicum) contains 44 terpene synthase (TPS) genes, including 29 that are functional or potentially functional. Of these 29 TPS genes, 26 were expressed in at least some organs or tissues of the plant. The enzymatic functions of eight of the TPS proteins were previously reported, and here we report the specific in vitro catalytic activity of 10 additional tomato terpene synthases. Many of the tomato TPS genes are found in clusters, notably on chromosomes 1, 2, 6, 8, and 10. All TPS family clades previously identified in angiosperms are also present in tomato. The largest clade of functional TPS genes found in tomato, with 12 members, is the TPS-a clade, and it appears to encode only sesquiterpene synthases, one of which is localized to the mitochondria, while the rest are likely cytosolic. A few additional sesquiterpene synthases are encoded by TPS-b clade genes. Some of the tomato sesquiterpene synthases use z,z-farnesyl diphosphate in vitro as well, or more efficiently than, the e,e-farnesyl diphosphate substrate. Genes encoding monoterpene synthases are also prevalent, and they fall into three clades: TPS-b, TPS-g, and TPS-e/f. With the exception of two enzymes involved in the synthesis of ent-kaurene, the precursor of gibberellins, no other tomato TPS genes could be demonstrated to encode diterpene synthases so far.

Highlights

  • Compounds of the terpenoid class play numerous roles in the interactions of plants with their environment, such as attracting pollinators and defending the plant against pests

  • terpene synthase (TPS)-e/f contains gymnosperm and angiosperm KS genes and various other TPSs

  • We report here that with a total of 29 functional or potentially functional genes and 15 mutated genes found to date, the tomato TPS gene family is similar in size to that of Arabidopsis

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Summary

Introduction

Compounds of the terpenoid class play numerous roles in the interactions of plants with their environment, such as attracting pollinators and defending the plant against pests. About one-third of the proteins encoded by its 32 functional or potentially functional TPS genes (the genome contains eight mutated TPS genes) have been assigned a biochemical function in the synthesis of monoterpenes, sesquiterpenes, and diterpenes in flowers, leaves, or roots (Sun and Kamiya, 1994; Yamaguchi et al, 1998; Bohlmann et al, 2000; Chen et al, 2003, 2004; Faldt et al, 2003; Tholl et al, 2005; Herde et al, 2008) The roles of these terpenes range from pollinator attraction to defense against a range of biotic agents (Gershenzon and Dudareva, 2007). Most of the functional Arabidopsis TPS genes are expressed constitutively, whereas some are induced under specific stress conditions (Tholl et al, 2005; Herde et al, 2008; Huang et al, 2010)

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