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.
Highlights
In response to herbivory, plants start to defend themselves against herbivores by producing toxins, repellents, antinutritives, etc., and by emitting a specific blend of volatile organic compounds (VOCs) that attract the carnivorous natural enemies of herbivores [1]
In order to assess the impact of manipulated VOCs on plantplant communications, we generated transgenic plants that constitutively biosynthesize and emit VOCs
We prepared gene constructs consisting of lima bean (E)-b-ocimene synthase PlOS [23] inserted downstream of the constitutive 35S cauliflower mosaic viral (CMV) promoter, and successfully generated a set of independent transgenic tobacco lines
Summary
Plants start to defend themselves against herbivores by producing toxins, repellents, antinutritives, etc. (induced direct defense), and by emitting a specific blend of volatile organic compounds (VOCs) that attract the carnivorous natural enemies of herbivores (induced indirect defense) [1]. The expression of genes involved in direct defense was not highly induced in the leaves exposed to one of the green leaf volatiles, (Z)-3-hexen-1-yl acetate (Hex-Ac), before herbivory, but was strongly induced once herbivores (gypsy moth larvae) began to feed [10]. Such priming effects were observed in maize plants which had been exposed to VOCs emitted from maize plants infested with generalist herbivores [11]. Exposure to the volatiles enhanced the emission of volatiles in receiver plants that could attract carnivorous natural enemies, which could help the plants’ indirect defense [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
