Metabolic engineering of the C₁₆ homoterpene TMTT in Lotus japonicus through overexpression of (E,E)‐geranyllinalool synthase attracts generalist and specialist predators in different manners

Abstract

SummaryPlant defenses against herbivores include the emission of specific blends of volatiles, which enable plants to attract natural enemies of herbivores.We characterized a plastidial terpene synthase gene, PlTPS2, from lima bean (Phaseolus lunatus). The recombinant PlTPS2 protein was multifunctional, producing linalool, (E)-nerolidol and (E,E)-geranyllinalool, precursors of (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene [TMTT].Transgenic Lotus japonicus and Nicotiana tabacum plants, expressing PlTPS2 or its homolog Medicago truncatula TPS3 (MtTPS3), were produced and used for bioassays with herbivorous and predatory mites. Transgenic L. japonicus plants expressing PlTPS2 produced (E,E)-geranyllinalool and TMTT, whereas wild-type plants and transgenic plants expressing MtTPS3 did not. Transgenic N. tabacum expressing PlTPS2 produced (E,E)-geranyllinalool but not TMTT. Moreover, in olfactory assays, the generalist predatory mite Neoseiulus californicus but not the specialist Phytoseiulus persimilis was attracted to uninfested, transgenic L. japonicus plants expressing PlTPS2 over wild-type plants. The specialist P. persimilis was more strongly attracted by the transgenic plants infested with spider mites than by infested wild-type plants.Predator responses to transgenic plant volatile TMTT depend on various background volatiles endogenously produced by the transgenic plants. Therefore, the manipulation of TMTT is an ideal platform for pest control via the attraction of generalist and specialist predators in different manners.

Identification, Functional Characterization, and Evolution of Terpene Synthases from a Basal Dicot

“…For instance, carnivorous predatory mites (Phytoseiulus persimilis) preferred the odor source of lima bean (Phaseolus lunatus) plants attacked by spider mites (Tetranychus urticae) to the odor of plants damaged by beet armyworm (Spodoptera exigua) larvae (de Boer et al, 2004). TMTT might also play a role in indirect defense in floral tissues (Brillada et al, 2013). Still, the role of geranyllinalool in plant tissues is not well established.…”

Characterization of Biosynthetic Pathways for the Production of the Volatile Homoterpenes DMNT and TMTT in Zea mays

“…This indicates that TPS2 is involved in the production of mono-, sesqui-, and diterpenes in planta. The closely related enzymes MtTPS3 from M. truncatula (Gomez et al, 2005;Arimura et al, 2008) and PlTPS2 from P. lunatus (Brillada et al, 2013) accept the same range of substrates in vitro, but their activities in the respective plant species have not been determined. The products of TPS2 have previously been identified as some of the major herbivore-induced volatiles of maize.…”

“…These enzymes convert GGDP more efficiently than FDP in vitro and their transcript levels correlate with the formation of TMTT (SlGLS) and hydroxylinalool glycosides (NaGLS). Two geranyllinallool synthases from Fabaceae, PlTPS2 from P. lunatus (Brillada et al, 2013) and MtTPS3 from Medicago truncatula (Gomez et al, 2005;Arimura et al, 2008), belong to a separate clade of terpene synthases possibly involved in volatile terpene production. These enzymes are expressed in the plastid and convert GDP and FDP with higher in vitro efficiencies than GGDP.…”

Volatile interaction between undamaged plants affects tritrophic interactions through changed plant volatile emission

“…7 The effects of TMTT and (E)-nerolidol as individual components or in blends have been studied mainly in predatory mites. 20,29 Coccinella septempunctata is an important predator of aphids, strongly attracted by volatiles of attacked plants, but knowledge of the role of these HIPV components on their behavior, alone or in blends, is lacking. It has been previously shown that ladybirds are attracted by changes in volatile profiles resulting from chemical interaction between unattacked barley plants 8,12,13 and the present study supports these findings and gives a potential explanation of the phenomenon.…”