The Composite Effect of Transgenic Plant Volatiles for Acquired Immunity to Herbivory Caused by Inter-Plant Communications

Abstract

A blend of volatile organic compounds (VOCs) emitted from plants induced by herbivory enables the priming of defensive responses in neighboring plants. These effects may provide insights useful for pest control achieved with transgenic-plant-emitted volatiles. We therefore investigated, under both laboratory and greenhouse conditions, the priming of defense responses in plants (lima bean and corn) by exposing them to transgenic-plant-volatiles (VOCos) including (E)-β-ocimene, emitted from transgenic tobacco plants (NtOS2) that were constitutively overexpressing (E)-β-ocimene synthase. When lima bean plants that had previously been placed downwind of NtOS2 in an open-flow tunnel were infested by spider mites, they were more defensive to spider mites and more attractive to predatory mites, in comparison to the infested plants that had been placed downwind of wild-type tobacco plants. This was similarly observed when the NtOS2-downwind maize plants were infested with Mythimna separata larvae, resulting in reduced larval growth and greater attraction of parasitic wasps (Cotesia kariyai). In a greenhouse experiment, we also found that lima bean plants (VOCos-receiver plants) placed near NtOS2 were more attractive when damaged by spider mites, in comparison to the infested plants that had been placed near the wild-type plants. More intriguingly, VOCs emitted from infested VOCos-receiver plants affected their conspecific neighboring plants to prime indirect defenses in response to herbivory. Altogether, these data suggest that transgenic-plant-emitted volatiles can enhance the ability to prime indirect defenses via both plant-plant and plant-plant-plant communications.

Volatile Organic Compounds (VOCs) Emitted by Ilex paraguariensis Plants are Affected by the Herbivory of the Lepidopteran Thelosia camina and the Coleopteran Hedypathes betulinus

“…15 Moreover, (E)-β-ocimene produced by transgenic plants (lima bean and corn) induced priming responses of other plants, successfully attracting predators and parasitoids. 16 In addition, β-ocimene induced the increase of methyl jasmonate and transcript levels of defense/stress-inducible genes in tissue levels in Arabidopsis thaliana DMNT (15) was produced in high amounts by yerba mate plants after both treatments of herbivory (TC and HB). DMNT and 4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT) are degradation products of the terpenoids nerolidol and geranlyl-linalool.…”

Plant–plant–plant communications, mediated by (E)-β-ocimene emitted from transgenic tobacco plants, prime indirect defense responses of lima beans

“…Notably, (E)-DMNT and TMTT have also been reported to function as airborne cues that attract predatory mites (de Boer et al 2004;Kappers et al 2005), which may explain our previously reported findings that infested, second receiver plants that had been placed near infested VOCos-receiver plants were more attractive to P. persimilis in comparison to those that had been placed near the infested VOCwt-receiver plants (Muroi et al 2011). …”

“…This was likely to have been caused by higher levels of VOCs, including methyl salicylate and (E)-DMNT, its isomer [(Z)-DMNT], and TMTT, released from VOCos-receiver bean plants following infestation of T. uriticae, compared to the T. urticae-infested VOCwt-receiver plants (Muroi et al 2011). As (E)-DMNT and TMTT, emitted as mite-induced lima bean leaf volatiles, are known to play a major role in the communication between damaged and undamaged leaves (Arimura et al 2000), the higher levels of those two VOCs from VOCos-receiver plants could…”

“…Transgenic tobacco plants were produced in a previous study (Muroi et al 2011). Briefly, an open reading frame of the (E)-b-ocimene synthase gene from lima bean (PlOS; EU194553) under the control of the CaMV35S promoter was inserted into a binary vector harboring the hygromycin phosphotransferase gene to produce the plasmid pSMAH-PlOS.…”

“…In a previous study, we used transgenic tobacco plants emitting (E)-bocimene [(E)-3,7-dimethyl-l,3,6-octatriene] as emitters for plantÁplant communication assays. We investigated the priming of defense responses in lima bean by exposing them to (E)-b-ocimene emitted from transgenic tobacco plants (NtOS2) that were constitutively overexpressing (E)-b-ocimene synthase (Muroi et al 2011). When lima bean plants that had previously been placed downwind of NtOS2 in an open-flow tunnel were infested by spider mites (Tetranychus urticae), they were more defensive against T. urticae and more attractive to the predatory mites (Phytoseiulus persimilis) in comparison to the infested plants that had been placed downwind of wild-type (WT) tobacco plants.…”