Ribosomal proteins promote leaf adaxial identity

Abstract

Establishing abaxial-adaxial polarity is central to leaf morphogenesis and function. Groups of genes that encode different components for leaf patterning have been identified in recent years. These include transcriptional factors, small RNAs, 26S proteasome and components required for post-transcriptional gene silencing and chromatin remodeling, showing a complex regulatory network and indicating that the regulation occurs at different levels. In this work, we report the identification and characterization of asymmetric leaves1/2 enhancer5 (ae5) and ae6 mutants. These two mutants had a phenotype of abnormal leaf patterning, with the abaxial mesophyll features appearing in the adaxial mesophyll domain, and double mutants ae5 as1/2 and ae6 as1/2 producing severely abaxialized leaves. AE5 and AE6 encode the ribosomal large subunit proteins RPL28A and RPL5A, respectively, and mutations in two other ribosomal protein genes, RPL5B and RPL24B, resulted in plant phenotypes similar to those of ae5 and ae6. Because these four ribosomal proteins are located in distinct sites in the ribosomal large subunit, we propose that the conserved translational function of the ribosome may be required for regulating key components during leaf patterning. Collectively, our data indicate that specific ribosome subunit-mediated translational control is essential in leaf polarity establishment.

Pumilio Puf domain RNA-binding proteins in Arabidopsis

“…[53][54][55] Although apum23 mutants show phenotypes and auxin distributions similar to those of RP gene mutants, further biochemical and molecular studies are needed to explain defective auxin homeostasis.…”

“…Because APUM23 is a nucleolar protein, it is possible that it has also other nucleolar functions such as rRnA byproduct degradation by exosome (3), a direct role in translation (4) or an indirect role via its role in ribosome biogenesis (5). Further, auxin and ribosome biogenesis are linked with each other such that defective ribosomes inhibit auxin biosynthesis [54][55][56] (6) and a local auxin accumulation can translationally repress ribosomal genes (7). 57 was supported by the Brain Korea 21 (BK21) program funded by the Ministry of Education, Science and Technology, Korea.…”

Plant L10 Ribosomal Proteins Have Different Roles during Development and Translation under Ultraviolet-B Stress

“…Mutations in ribosomal proteins have been reported as showing abnormalities in growth and development (Van Lijsebettens et al, 1994;Ito et al, 2000;Weijers et al, 2001;Nishimura et al, 2005;Degenhardt and Bonham-Smith, 2008a;Imai et al, 2008, Pinon et al, 2008Yao et al, 2008;Byrne, 2009;Fujikura et al, 2009;Rosado et al 2010). As mentioned above, homozygous rpl10B plants were significantly underrepresented.…”

“…In Arabidopsis, numerous mutants have been described with altered leaf size and/or shape (Van Lijsebettens et al, 1994;Ito et al, 2000;Weijers et al, 2001;Nishimura et al, 2005;Degenhardt and Bonham-Smith, 2008a;Pinon et al, 2008;Yao et al, 2008;Fujikura et al, 2009;Rosado et al, 2010). rpl10B mutant plants displayed smaller palisade cells in the subepidermal layer (76% reduction) and also showed a moderate but significant decrease in cell number in the first leaves (32% reduction; Fig.…”

Involvement of ribosomal protein RPL27a in meristem activity and organ development

“…6 Ribosomal proteins are also involved in embryo development and patterning, leaf dorsoventral polarity, floral organ patterning, the time to flowering and gametophyte viability, particularly in the female. [7][8][9][10][11][12][13][14][15][16] The discrete phenotypes of ribosomal protein mutants have lead to the suggestion that ribosomes play a regulatory role in development.…”