A maize landrace that emits defense volatiles in response to herbivore eggs possesses a strongly inducible terpene synthase gene

Abstract

Maize (Zea mays) emits volatile terpenes in response to insect feeding and egg deposition to defend itself against harmful pests. However, maize cultivars differ strongly in their ability to produce the defense signal. To further understand the agroecological role and underlying genetic mechanisms for variation in terpene emission among maize cultivars, we studied the production of an important signaling component (E)‐caryophyllene in a South American maize landrace Braz1006 possessing stemborer Chilo partellus egg inducible defense trait, in comparison with the European maize line Delprim and North American inbred line B73. The (E) ‐caryophyllene production level and transcript abundance of TPS23, terpene synthase responsible for (E) ‐caryophyllene formation, were compared between Braz1006, Delprim, and B73 after mimicked herbivory. Braz1006–TPS23 was heterologously expressed in E. coli, and amino acid sequences were determined. Furthermore, electrophysiological and behavioral responses of a key parasitic wasp Cotesia sesamiae to C. partellus egg‐induced Braz1006 volatiles were determined using coupled gas chromatography electroantennography and olfactometer bioassay studies. After elicitor treatment, Braz1006 released eightfold higher (E)‐caryophyllene than Delprim, whereas no (E)‐caryophyllene was detected in B73. The superior (E)‐caryophyllene production by Braz1006 was positively correlated with high transcript levels of TPS23 in the landrace compared to Delprim. TPS23 alleles from Braz1006 showed dissimilarities at different sequence positions with Delprim and B73 and encodes an active enzyme. Cotesia sesamiae was attracted to egg‐induced volatiles from Braz1006 and synthetic (E)‐caryophyllene. The variation in (E)‐caryophyllene emission between Braz1006 and Delprim is positively correlated with induced levels of TPS23 transcripts. The enhanced TPS23 activity and corresponding (E)‐caryophyllene production by the maize landrace could be attributed to the differences in amino acid sequence with the other maize lines. This study suggested that the same analogous genes could have contrasting expression patterns in different maize genetic backgrounds. The current findings provide valuable insight not only into genetic mechanisms underlying variation in defense signal production but also the prospect of introgressing the novel defense traits into elite maize varieties for effective and ecologically sound protection of crops against damaging insect pests.

Overexpression of the caryophyllene synthase gene GhTPS1 in cotton negatively affects multiple pests while attracting parasitoids

“…Throughout the breeding process, certain volatile traits may have been lost, as was the case for North American maize varieties, which lack the transcription of ( E )‐β‐caryophyllene synthase gene TPS23 and thus do not emit ( E )‐β‐caryophyllene . The wide variety of cultivated cotton genotypes and wild plants of Gossypium species may contain a spectrum of different volatiles.…”

“…Nematode attraction could be enhanced by restoring ( E )‐β‐caryophyllene emissions in American maize . In maize, ( E )‐β‐caryophyllene also attracts the parasitoid wasp Cotesia marginiventris (Hymenoptera: Braconidae) and Cotesia sesamiae (Hymenoptera: Braconidae) which parasitize the larvae of Spodoptera littoralis (Lepidoptera: Noctuidae) and Chilo partellus (Lepidoptera; Pyralidae), respectively . Therefore, effective utilization of terpene volatile emitted from plants can be an important ‘green’ control method against insect pests.…”

Removing constraints to sustainable food production: new ways to exploit secondary metabolism from companion planting and GM

“…In the push‐pull system for small‐holder cereal farming, companion plants are used to release the stress‐related defence signals DMNT and TMTT. The production of these compounds can be induced in certain maize plants, for example the ancestors, the teosintes, and the landraces and open pollinated varieties (OPVs) derived from these, by oviposition by the stem borer moths, C. partellus . Hybrid maize does not normally contain such a trait unless from a breeding programme without use of insecticides.…”

Volatile Semiochemical Mediated Plant Defense in Cereals: A Novel Strategy for Crop Protection

“…Moreover, the HIPVs were produced locally at the site of insect attack and systemically throughout the plant [13]. These HIPVs attract natural enemies of the herbivores, the parasitic wasp Cotesia sesamiae and entomopathogenic nematodes [19,20]. The identities of bioactive HIPVs emitted in response to herbivore feeding and oviposition include (E)-ocimene, (R)-linalool, methyl salicylate, decanal, methyl eugenol, (E)-caryophyllene, (E)-β-farnesene, α-bergamotene, DMNT, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene (TMTT) (Figure 1).…”

“…Agronomy 2017, 7, 58 3 of 8 sesamiae and entomopathogenic nematodes [19,20]. The identities of bioactive HIPVs emitted in response to herbivore feeding and oviposition include (E)-ocimene, (R)-linalool, methyl salicylate, decanal, methyl eugenol, (E)-caryophyllene, (E)-β-farnesene, α-bergamotene, DMNT, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene (TMTT) ( Figure 1).…”