Genetically engineered maize plants reveal distinct costs and benefits of constitutive volatile emissions in the field

• Published in: Plant biotechnology journal 2013-06, Vol.11 (5), p.628-639
• Main Authors: Robert, Christelle Aurélie Maud, Erb, Matthias, Hiltpold, Ivan, Hibbard, Bruce Elliott, Gaillard, Mickaël David Philippe, Bilat, Julia, Degenhardt, Jörg, Cambet‐Petit‐Jean, Xavier, Turlings, Ted Christiaan Joannes, Zwahlen, Claudia
• Format: Article
• Language: English
• Subjects: (E)‐β‐caryophyllene; aboveground herbivory; Adults; Alkyl and Aryl Transferases - metabolism; Animals; belowground herbivory; Biochemistry; Biosynthesis; Caryophyllene; Corn; Costs; Damage; Diabrotica undecimpunctata; Diabrotica virgifera virgifera; Ecological effects; Ecology; Emission; Emissions; Entomopathogenic nematodes; Genetic Engineering; Genetic transformation; Germination; Herbivores; Herbivory; Humulene; Insecta - physiology; Larvae; Metabolism; Nematoda; Nematoda - physiology; Pest control; Pests; Physiological effects; Physiology; Plant Development; Plant growth; Plant resistance; Plant Roots - physiology; Plants, Genetically Modified; Pollinators; Risk Assessment; Scholarly publishing; Seed germination; Sesquiterpenes - metabolism; Spodoptera frugiperda; Terpene synthase; Terpenes - metabolism; terpenoid‐engineered plants; Trends; volatile emission benefits; volatile emission costs; Volatile Organic Compounds - metabolism; Zea mays; Zea mays - enzymology; Zea mays - genetics; Zea mays - metabolism
• ISSN: 1467-7644; 1467-7652
• DOI: 10.1111/pbi.12053

Summary Genetic manipulation of plant volatile emissions is a promising tool to enhance plant defences against herbivores. However, the potential costs associated with the manipulation of specific volatile synthase genes are unknown. Therefore, we investigated the physiological and ecological effects of transforming a maize line with a terpene synthase gene in field and laboratory assays, both above‐ and below ground. The transformation, which resulted in the constitutive emission of (E)‐β‐caryophyllene and α‐humulene, was found to compromise seed germination, plant growth and yield. These physiological costs provide a possible explanation for the inducibility of an (E)‐β‐caryophyllene‐synthase gene in wild and cultivated maize. The overexpression of the terpene synthase gene did not impair plant resistance nor volatile emission. However, constitutive terpenoid emission increased plant apparency to herbivores, including adults and larvae of the above ground pest Spodoptera frugiperda, resulting in an increase in leaf damage. Although terpenoid overproducing lines were also attractive to the specialist root herbivore Diabrotica virgifera virgifera below ground, they did not suffer more root damage in the field, possibly because of the enhanced attraction of entomopathogenic nematodes. Furthermore, fewer adults of the root herbivore Diabrotica undecimpunctata howardii were found to emerge near plants that emitted (E)‐β‐caryophyllene and α‐humulene. Yet, overall, under the given field conditions, the costs of constitutive volatile production overshadowed its benefits. This study highlights the need for a thorough assessment of the physiological and ecological consequences of genetically engineering plant signals in the field to determine the potential of this approach for sustainable pest management strategies.