Author
|
Submitted to: International Plant Resistance to Insects Workshop Abstracts & Proceedings
Publication Type: Abstract Only Publication Acceptance Date: 1/4/2008 Publication Date: 2/10/2008 Citation: Chen, M. 2008. Transcriptional and Metabolic Reprogramming of Host Plants Following Hessian Fly Attack during Compatible and Incompatible Interactions. International Plant Resistance to Insects Workshop Abstracts & Proceedings. Interpretive Summary: Plant defense involves three major steps: surveillance, signal transduction, and the production of defense chemicals. A great deal of information on signal perception and transduction has been revealed in numerous plant-parasite systems. Here we investigated changes in metabolic pathways which might lead to accumulation of defense chemicals using genomic and metabolic profiling. Wheat-Hessian fly interaction was used in this study. Hessian fly is an insect but shares many features with plant pathogens, being sessile during feeding stages and having avirulence genes that match plant resistance genes in gene-for-gene relationships. Many genes involved in Carbon/Nitrogen (C/N) metabolism were differentially regulated during compatible and incompatible interactions. During compatible interactions, the attacking site became a carbon sink. Photoassimilates were transported to the attacking site from other parts of the plant. Part of the transported photoassimilates were converted into amino acids through coordinated activation of key metabolic pathways including glycolysis, the tricarboxylic acid cycle, and amino acid synthesis pathways. In contrast, the attacking site became a nitrogen sink during incompatible interactions. Nitrogen was transported to the attacking site from other parts of the plant in the form of asparagine. The transported nitrogen was likely converted into defensive secondary metabolites. Our data suggested that the formation of a carbon sink and the conversion of C-compounds into N-compounds at the feeding site is a necessary condition for Hessian fly larvae to survive and develop in susceptible plants, whereas the formation of a nitrogen sink and the increase in phenylpropanoids and other secondary metabolites may be part of the resistance mechanism. Technical Abstract: Plant defense involves three major steps: surveillance, signal transduction, and the production of defense chemicals. A great deal of information on signal perception and transduction has been revealed in numerous plant-parasite systems. Here we investigated changes in metabolic pathways which might lead to accumulation of defense chemicals using genomic and metabolic profiling. Wheat-Hessian fly interaction was used in this study. Hessian fly is an insect but shares many features with plant pathogens, being sessile during feeding stages and having avirulence genes that match plant resistance genes in gene-for-gene relationships. Many genes involved in Carbon/Nitrogen (C/N) metabolism were differentially regulated during compatible and incompatible interactions. During compatible interactions, the attacking site became a carbon sink. Photoassimilates were transported to the attacking site from other parts of the plant. Part of the transported photoassimilates were converted into amino acids through coordinated activation of key metabolic pathways including glycolysis, the tricarboxylic acid cycle, and amino acid synthesis pathways. In contrast, the attacking site became a nitrogen sink during incompatible interactions. Nitrogen was transported to the attacking site from other parts of the plant in the form of asparagine. The transported nitrogen was likely converted into defensive secondary metabolites. Our data suggested that the formation of a carbon sink and the conversion of C-compounds into N-compounds at the feeding site is a necessary condition for Hessian fly larvae to survive and develop in susceptible plants, whereas the formation of a nitrogen sink and the increase in phenylpropanoids and other secondary metabolites may be part of the resistance mechanism. |
