Chung K, Tasaka M

Arabidopsis semi-dominant uni-1D shows both constitutive defense responses and diverse morphological defects. Especially, uni-1D homozygote (uni-1D) mutants exhibit severe phenotypes including not only highly up-regulated pathogenesis related-1(PR-1) gene expression, but also lethality in the early stage of true leaf formation after germination. The gene responsible for the mutant encodes a ...

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coiled coil-nucleotide binding site-leucine rich repeat (CC-NBS-LRR)-type R protein that functions in the recognition of pathogen and the triggering of defense responses. However, the molecular basis of how uni-1D can induce these phenotypes was unknown. In this study, we isolated the regulatory particle triple-ATPase subunits (RPT) 2a and 2b, base components of the 19S regulatory particle in 26S proteasome, as uni-1D-interacting proteins using yeast two hybrid screening. Genetic studies showed that crossing with the rpt2a reduces the level of uni-1D-induced PR-1 gene expression and suppresses the lethality of the uni-1D, by leading to restoration of lost expression of the WUSCHEL gene, which functions to maintain meristem activity, in the shoot apical mersitem of the uni-1D. These results suggest that RPT2a is a major interacting partner of uni-1D/UNI, and that the interaction between uni-1D and RPT2a is responsible for activating both morphology and defense signals.

Date: Jul. 26, 2011

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