A maize sesquiterpene cyclase gene induced by insect herbivory and volicitin: Characterization of wild-type and mutant alleles

Abstract

Plants can defend themselves from herbivorous insects by emitting volatile chemical signals that attract natural enemies of the herbivore. For example, maize seedlings attacked by beet armyworm larvae (Spodoptera exigua) produce a mixture of terpenoid and indole volatiles that serve to attract parasitic wasps. A key step in terpenoid biosynthesis is the conversion of acyclic prenyl diphosphates to terpenoid compounds by specific terpenoid synthases (cyclases). We have cloned a maize sesquiterpene cyclase gene, stc1, by transposon tagging and have identified two deletion mutations of the gene. The stc1 gene is located on chromosome 9S and does not seem to have a closely related ortholog in the maize genome. It is induced 15-to 30-fold in maize leaves by beet armyworm larvae feeding or by application of purified volicitin, the insect-derived elicitor, at a mechanically wounded site. stc1 induction is systemic, because undamaged leaves of the same plant show a similar increase in stc1 transcription. Analysis of volatiles from volicitin-treated seedlings revealed that a major naphthalene-based sesquiterpene was present in wild-type seedlings but absent in the Ac-insertion and x-ray-deletion mutants. Therefore, we have identified a maize gene that responds to caterpillar herbivory by producing a chemical defense signal that most likely serves to attract natural enemies of the herbivore.

Free Phenols in Maize Pith and Their Relationship with Resistance to <I>Sesamia nonagrioides</I> (Lepidoptera: Noctuidae) Attack

“…The relative trend for resistance was generally consistent whether the insects fed on undamaged or previously damaged leaves, but we cannot rule out that the relationship may change over time due to resistance factors induced specifically by insect feeding, which can vary depending on the insect species involved (Rodriguez-Saona et al 2010). However, based on reports in maize (Shen et al 2000), the time frame we used for the assays should have been sufficient to observe induced responses.…”

The Role of Indole and Other Shikimic Acid Derived Maize Volatiles in the Attraction of Two Parasitic Wasps

“…In maize plants, the mechanisms of biosynthesis, induction, and release of HIPVs are well characterized Frey et al, 2000;Shen et al, 2000;Schnee et al, 2002;Gouinguené et al, 2003;Schmelz et al, 2003a,b,c;Köllner et al, 2004;Lawrence and Novak, 2004;Ruther and Kleier, 2005), and the ecological significance of these compounds in tritrophic signaling has been demonstrated in laboratory and field experiments (Turlings et al, 1990;Bernasconi et al, 1998;Hoballah and Turlings, 2001;Fritzsche Hoballah et al, 2002;Rasmann et al, 2005). In particular, the role of green leaf volatiles and terpenoids in attracting natural enemies of the herbivores has been investigated in various experiments (D'Alessandro and Turlings, 2005;Hoballah and Turlings, 2005).…”

Functional Characterization of Nine Norway Spruce TPS Genes and Evolution of Gymnosperm Terpene Synthases of the TPS-d Subfamily

“…However, the known grand fir and few loblolly pine TPS genes cannot account for all oleoresin terpenoids in conifers. Nothing is known about TPS genes of induced volatile emissions in conifers , and only a few TPS genes of herbivore-induced terpene emission are known in other angiosperm plants (Shen et al, 2000;Schnee et al, 2002;Fäldt et al, 2003a;Arimura et al, 2004). Species of spruce (Picea spp.…”