These authors contributed equally to this work.
Regulation of leaf organ size by the Arabidopsis RPT2a 19S proteasome subunit
Article first published online: 24 JUN 2009
© 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd
The Plant Journal
Volume 60, Issue 1, pages 68–78, October 2009
How to Cite
Sonoda, Y., Sako, K., Maki, Y., Yamazaki, N., Yamamoto, H., Ikeda, A. and Yamaguchi, J. (2009), Regulation of leaf organ size by the Arabidopsis RPT2a 19S proteasome subunit. The Plant Journal, 60: 68–78. doi: 10.1111/j.1365-313X.2009.03932.x
- Issue published online: 24 SEP 2009
- Article first published online: 24 JUN 2009
- Received 15 January 2009; revised 21 April 2009; accepted 12 May 2009; published online 24 June 2009.
- 26S proteasome;
- cell size;
- 19S RP;
- leaf size;
The ubiquitin/26S proteasome pathway plays a central role in the degradation of short-lived regulatory proteins, to control many cellular events. To further understand this pathway, we focused on the RPT2 subunit of the 26S proteasome regulatory particle. The Arabidopsis genome contains two genes, AtRPT2a and AtRPT2b, which encode paralog molecules of the RPT2 subunit, with a difference of only three amino acids in the protein sequences. Both genes showed similar mRNA accumulation patterns. However, the rpt2a mutant showed a specific phenotype of enlarged leaves caused by increased cell size, in correlation with increased ploidy. Detailed analyses revealed that cell expansion is increased in the rpt2a mutant by extended endoreduplication early in leaf development. The transcription of genes encoding cell cycle-related components, for DNA replication licensing and the G2/M phase, was also promoted in the rpt2a mutant, suggesting that extended endoreduplication was caused by increased DNA replication, and disrupted regulation of the G2/M checkpoint, at the proliferation stage of leaf development.