|Samac, Deborah - Debby|
Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2007
Publication Date: 7/28/2007
Citation: Samac, D.A., Penuela, S., Foster-Hartnett, D., Hunt, E.N., Schnurr, J.A. 2007. Roles of defense response genes in plant-microbe interactions [abstract]. Phytopathology. 97:S103.
Technical Abstract: Microarray technology was used to identify genes associated with disease defense responses in the model legume Medicago truncatula. We compared transcript profiles from leaves inoculated with Colletotrichum trifolii and Erysiphe pisi and roots infected with Phytophthora medicaginis to identify genes expressed in response to all three pathogens and genes unique to an interaction. Among the most strongly up-regulated genes in all three interactions were a hevein-like protein, thaumatin-like protein (TLP), and members of the pathogenesis response (PR) 10 family. Transcripts of genes for enzymes in the phenylpropanoid pathway leading to production of isoflavonoid phytoalexins increased dramatically in response to inoculation with the foliar pathogens. In P. medicaginis-inoculated roots, transcripts of genes in the phenylpropanoid pathway peaked at 5 days post-inoculation, when symptoms became visible. M. truncatula plants expressing interfering RNA (RNAi) constructs were produced to evaluate the role of a TLP, PR-10 family member and chalcone synthase (CHS) in disease resistance. Reduced expression of CHS resulted in increased susceptibility to multiple pathogens and reduced pigmentation in seed pods. These results show that several CHS family members were silenced with a single RNAi construct and expression of CHS is critical for disease resistance in M. truncatula.