|RICHTER, ANNETT - Martin Luther University|
|SCHAFF, CLAUDIA - Martin Luther University|
|ZHANG, ZHIWU - Cornell University|
|LIPKA, ALEXANDER - Cornell University|
|TIAN, FENG - Cornell University|
|KOLLNER, TOBIAS - Max Planck Institute Of Chemical Ecology|
|SCHNEE, CHRISTIANE - Max Planck Institute Of Chemical Ecology|
|PREIB, SUSANNE - Martin Luther University|
|IRMISCH, SANDRA - Max Planck Institute Of Chemical Ecology|
|JANDER, GEORG - Boyce Thompson Institute|
|BOLAND, WILLHELM - Max Planck Institute Of Chemical Ecology|
|GERSHENZON, JOHNATHAN - Max Planck Institute Of Chemical Ecology|
|Buckler, Edward - Ed|
|DEGENHARDT, JORG - Martin Luther University|
Submitted to: The Plant Cell
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2016
Publication Date: 9/23/2016
Citation: Richter, A., Schaff, C., Zhang, Z., Lipka, A., Tian, F., Kollner, T., Schnee, C., Preib, S., Irmisch, S., Jander, G., Boland, W., Gershenzon, J., Buckler IV, E.S., Degenhardt, J. 2016. Characterization of biosynthetic pathways for the production of the volatile homoterpenes DMNT and TMTT in Zea mays. The Plant Cell. 28:2651-2665.
Interpretive Summary: Plants communicate with other organisms by using a wide range of volatile chemicals. These chemicals can be used by plants to attract the predators of herbivores that are eating them. In the case of maize, when caterpillars starts eating its leaves, it releases chemicals to attract caterpillar predators. In one of the largest ever studies of volatiles, over 5,000 varieties of maize were surveyed for their release of volatiles. By genetic mapping, the key regulators of the terpenes (volatiles) pathways were discovered and verified by a range of approaches. This study provides a catalog to the natural variation that can be used in maize breeding for herbivore defense using the native defense mechanisms.
Technical Abstract: Plant volatiles not only have multiple defense functions against herbivores, fungi, and bacteria, but also have been implicated in signaling within the plant and toward other organisms. Elucidating the function of individual plant volatiles will require more knowledge of their biosynthesis and regulation in response to external stimuli. By exploiting the variation of herbivore-induced volatiles among 26 maize (Zea mays) inbred lines, we conducted a nested association mapping and genome-wide association study (GWAS) to identify a set of quantitative trait loci (QTLs) for investigating the pathways of volatile terpene production. The most significant identified QTL affects the emission of (E)-nerolidol, linalool, and the two homoterpenes (E)-3,8-dimethyl-1,4,7-nonatriene (DMNT) and (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT). GWAS associated a single nucleotide polymorphism in the promoter of the gene encoding the terpene synthase TPS2 with this QTL. Biochemical characterization of TPS2 verified that this plastid-localized enzyme forms linalool, (E)-nerolidol, and (E,E)-geranyllinalool. The subsequent conversion of (E)-nerolidol into DMNT maps to a P450 monooxygenase, CYP92C5, which is capable of converting nerolidol into DMNT by oxidative degradation. A QTL influencing TMTT accumulation corresponds to a similar monooxygenase, CYP92C6, which is specific for the conversion of (E,E)-geranyllinalool to TMTT. The DMNT biosynthetic pathway and both monooxygenases are distinct from those previously characterized for DMNT and TMTT synthesis in Arabidopsis thaliana, suggesting independent evolution of these enzymatic activities.