Date of Award

1-1-2010

Document Type

Campus Access Dissertation

Department

Biological Sciences

First Advisor

Johannes W. Stratmann

Abstract

The COP9 Signalosome (CSN) is an evolutionarily conserved multi-protein complex that regulates proteasome-mediated proteolysis. While the CSN has been shown to function in various growth and developmental processes, the involvement of the CSN in the regulation of defense responses is largely unknown. It was shown that silencing of the CSN subunit CSN5 resulted in reduced wound-and herbivory-induced levels of jasmonic acid and reduced expression of wound-response genes. Unexpectedly, these plants also showed increased pathogenesis-related gene expression. Consequently, CSN5–silenced plants were more susceptible to feeding by herbivorous insects and infection by a necrotrophic fungus.

It has been shown previously in our lab that a MAP kinase signaling cascade is an essential part of systemin-mediated defense signaling and functions upstream of jasmonic acid biosynthesis. Co-silencing of MPK1/2 and CSN5 had a synergistic effect on pathogenesis-related gene expression, suggesting that they function in the same signaling network. Together these finding suggest a role for the CSN in regulating jasmonic acid-dependent plant defense responses.

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