Location: Wheat, Sorghum and Forage Research
Project Number: 3042-21220-033-02-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2016
End Date: Aug 31, 2021
Insects pests regularly threaten sorghum production in the Great Plains region, and this threat is likely to increase in magnitude and severity due to climate change. Plants synthesize phenolic compounds as a generalized defense response against insect herbivory. Components of these metabolic pathways are also targets to improve plants for bioenergy uses, because the precursors to the cell wall polymer lignin are derived from phenylpropanoid metabolism. However, impact of lignin modification in sorghum on insect resistance/tolerance has not been fully investigated. Specific objectives: 1. Characterize sorghum genes involved in resistance against different feeding guilds of insects. 2. Determine novel defense metabolites in sorghum against insect pests.
ARS has developed a series of sorghum lines with altered phenylpropanoid metabolism. To increase flux toward lignin biosynthesis, 11 over-expression constructs under control of the 35S promoter, each construct contains a gene encoding different enzyme in monolignol biosynthesis, and one gene encodes a regulatory protein were transformed into sorghum. To impair lignin synthesis sorghum, ARS has developed three brown midrib (bmr) lines, bmr2, 6 and 12, which are impaired 4-coumarate Coenzyme A Ligase (4CL), cinnamyl alcohol dehydrogenase (CAD) and caffeic acid O-methyltransferase (COMT) activities, respectively. The interactions between these sorghum lines and different feeding guilds of insects will be evaluated. The aboveground feeding insects include both chewing (European Corn Borer; Ostrinia nubilalis) and piercing-sucking (Corn Leaf Aphid; Rhopalosiphum maidis and Sugarcane Aphid; Melanaphis sacchari). Belowground feeding insect pests include the root feeder (Western Corn Rootworm; Diabrotica virgifera virgifera).