UBC Theses and Dissertations
Arabidopsis MKK6 functions in parallel with MKK1 and MKK2 to negatively regulate plant immunity Gao, Fang
As an early defense response, MAP kinase cascade activation plays important roles in transduction and amplification of signals upon pathogen perception in plants. The Arabidopsis MEKK1-MKK1/MKK2-MPK4 kinase cascade was previously shown to negatively regulate plant immunity. In this study, two suppressors of the mkk1 mkk2 double mutant – summ4-1D and summ4-2D have been identified and characterized. summ4-1D and summ4-2D contain mutations in the promoter region of MKK6, which leads to elevated expression of MKK6, causing suppression of the mkk1 mkk2 autoimmune phenotypes. However, the autoimmune phenotypes of mekk1 and mpk4 cannot be suppressed by summ4-1D. MKK6 interacts with MEKK1 and MPK4, and MPK4 activation is blocked in mkk1 mkk2, but is recovered in the summ4-1D mkk1 mkk2 triple mutant background. These results suggest that MKK6 functions in parallel with MKK1 and MKK2 to negatively regulate plant immunity.
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