Location: Crop Bioprotection ResearchTitle: Effects of overexpressing individual lignin biosynthetic enzymes on feeding and growth of corn earworms and fall armyworms
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/21/2016
Publication Date: 9/25/2016
Citation: Dowd, P.F., Clemente, T.E., Sattler, S.E. 2016. Effects of overexpressing individual lignin biosynthetic enzymes on feeding and growth of corn earworms and fall armyworms. Meeting Abstract. DOI: 10.1630/ICE.2016.110247.
Technical Abstract: Lignin is an important insect resistance component of plants. Enhancing or disrupting the lignin biosynthetic pathway for different bioenergy uses may alter pest resistance. The lignin biosynthetic pathway is complex, and a number of pathway compounds are also involved in the biosynthesis of simpler defensive secondary metabolites. Several sorghum lignin biosynthetic genes were overexpressed in transgenic sorghum lines, including caffeic acid O-methyl transferase, caffeoyl CoA O-methyl transferase, cinnamate 4-hydroxylase, cinnamyl alcohol dehydrogenase, 4-coumarate CoA ligase, ferulate 5-hydroxylase, SbMyb60 transcription factor, and phenylalanine ammonia lyase. Leaves from progeny plants of two positive transformation events for each gene were examined for feeding damage by first instar corn earworms and fall armyworms. Weights of caterpillars were also determined. Both increases and decreases in feeding rates and weights were noted relative to wild type plants. In some cases, increased feeding was associated with lower weights, suggesting a nutritional effect, while in other cases, decreased feeding was associated with lower weights, suggesting a toxic effect. Responses of the two insects to the same overexpressed gene construct also varied. For example, fall armyworms fed leaves from plants overexpressing caffeoyl CoA O-methyl transferase weighed significantly less than those fed leaves from wild type plants, while the opposite was observed for corn earworms. This study highlights the complex interactions between insects and the biosynthesis of defensive compounds by plants, which should be evaluated as part of bioenergy feedstock development.