Variability in herbivore-induced odour emissions among maize cultivars and their wild ancestors (teosinte)

Abstract

Summary. Maize plants respond to caterpillar feeding with the release of relatively large amounts of specific volatiles, which are known to serve as cues for parasitoids to locate their host. Little is known about the genetic variability in such herbivore-induced plant signals and about how the emissions in cultivated plants compare to those of their wild relatives. For this reason we compared the total quantity and the qualitative composition of the odour blend among eleven maize cultivars and five wild Zea (Poaceae) species (teosinte), as well as among the offspring of eight Zea mays mexicana plants from a single population. Young plants were induced to release volatiles by mechanically damaging the leaves and applying oral secretions of Spodoptera littoralis (Lepidoptera: Noctuidae) caterpillars to the wounded sites. Volatiles were collected 7 h after treatment and subsequently analysed by gas chromatography. The total amounts of volatiles released were significantly different among maize cultivars as well as among the teosintes. Moreover, striking differences were found in the composition of the induced odour blends. Caryophyllene, for instance, was released by some, but not all varieties and teosintes, and the ratios among monoterpenes and sesquiterpenes varied considerably. The offspring of different mother plants of the Z. m. mexicana population showed some variation in the total amounts that they released, but the composition of the odour blend was very consistent within the population of this teosinte species. We discuss the ecological significance of these findings in terms of specificity and reliability of induced plant signals for parasitoids.

Evaluating the Induced-Odour Emission of a Bt Maize and its Attractiveness to Parasitic Wasps

“…emissions among different maize lines (Gouinguene´et al, 2001;Fritzsche-Hoballah et al, 2002;Degen et al, 2004). Variability among maize lines is tremendous and it can be concluded that both maize lines tested here produce a volatile blend that falls well within the common range.…”

“…These same compounds are commonly released by many other maize varieties in response to caterpillar feeding (Figure 1; Gouinguene´et al, 2001;Fritzsche-Hoballah et al, 2002;Degen et al, 2004). The ratios among the compounds are also common and did not differ between the isogenic and transgenic line.…”

“…The odour emissions are systemic and are triggered by elicitors in the oral secretions of the caterpillars. There is considerable variability among maize varieties in the quantities and relative composition of these signals (Gouinguene´et al, 2001;Fritzsche-Hoballah et al, 2002). We recently tested the volatile emissions of 31 maize inbred lines that are commonly used by U.S. and European breeders to select new maize varieties for commercial use .…”

Aphid acceptance of Hordeum genotypes is affected by plant volatile exposure and is correlated with aphid growth

“…However, genotype specific differences in volatile emissions from undamaged plants have been found in potato (Wang and Kays 2002), rice (Rapusas et al 1996), cotton (Elzen et al 1986) and pear (Scutareanu et al 2003). A high genetic variability in volatile emissions from herbivore-damaged plants has also been shown in cotton (Loughrin et al 1995) and maize (Degen et al 2004;Gouinguené et al 2001). In other plant-herbivore systems, various organic compounds produced in response to plant damage have been shown to affect plant defence and plant gene expression in neighbouring plants, deterring herbivores and attracting their natural enemies (Dicke et al 2003;Baldwin et al 2006).…”

Variation In Plant Volatiles and Attraction Of The ParasitoidDiadegma semiclausum(Hellén)

“…These are emitted upon damage by the host and are both reliable and detectable. In natural ecosystems, host-parasitoid interactions take place in habitats composed of several to many plant species, where both the expectancy of the host's presence and the specificity of volatile infochemicals may show great between-and within-plant variation (Takabayashi et al, 1994;De Moraes et al, 1998;Vet, 1999;Gouinguené, 2001). Variation in odors among plant species and cultivars can be greater than between damaged and undamaged conspecific plants (Geervliet et al, 1997), and such differences can be reflected in the attractance of parasitoids to plants (Elzen et al, 1983(Elzen et al, , 1986Fox and Eisenbach, 1992;Geervliet et al, 1996).…”