Submitted to: Plant and Animal Genome Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/4/2009
Publication Date: 1/8/2010
Citation: Williams, C.E., Subramanyam, S., Sardesai, N., Zheng, C., Minocha, S. 2010. Virulent Hessian Fly Larvae Trigger Increased Wheat Polyamine Levels. Plant and Animal Genome Conference Proceedings. Available at: http://www.intl-pag.org/18/abstracts/P07c_PAGXVIII_797.html. Interpretive Summary:
Technical Abstract: Insect herbivores depend on dietary amino acids and polyamines (PA) for their growth and development. We have analyzed polyamine metabolism during the interaction of wheat with one of its major insect pests, the Hessian fly. The wheat-Hessian fly interaction operates in a gene-for-gene manner resulting in either compatible (susceptible plant) or incompatible (resistant plant) interactions. Feeding by Hessian fly larvae results in significantly higher transcript levels of genes encoding key PA biosynthesis enzymes (Ornthine decarboxylase, S-adenosyl methionine decarboxylase and S-adenosyl methionine synthetase) in susceptible plants as compared to resistant and uninfested plants. Expression profiles for genes from the amino acid biosynthesis pathway (Pyrroline-5-carboxylate synthetase, Arginine decarboxylase and Acetylornithinase) that feed into the PA biosynthesis pathway indicate preferential synthesis of wheat polyamines from ornithine instead of arginine. Increase in transcripts of PA pathway genes is accompanied by increased S-adenosyl methionine decarboxylase activity, as well as higher levels of free polyamines (putrescine, spermidine and spermine) in susceptible plants. A concurrent increase in PA levels in the virulent larvae inhabiting and feeding on the susceptible plant suggests that plants are the source of polyamines for the larvae. Inhibition of Ornthine decarboxylase activity in the susceptible plants using an inhibitor, DL-'- difluoromethylornithine, resulted in reduction of virulent larval size highlighting the importance of polyamines in their diet. Our results demonstrate the manipulation of metabolic pathways in wheat by virulent Hessian fly larvae leading to increased production of polyamines that are utilized by these larvae for their own growth and development.