The ang3 mutation identified the ribosomal protein gene RPL5B with a role in cell expansion during organ growth.
The role of translation in the regulation of higher plant growth and development is not well understood. Mutational analysis is a powerful tool to identify and study the function of genes related to a biological process, such as growth. Here we analyzed functionally the angusta3 (ang3) narrow leaf mutant. The AG3 gene was cloned by fine mapping combined with candidate gene sequencing and it corresponded to the ribosomal protein gene RPL5B. Based on amino acid sequence homology, promoter DNA sequence homology and in silico gene expression analysis, RPL5B was found to be putatively functionally redundant with RPL5A. The morphological analysis of ang3 mutants showed that the leaf lamina area was significantly reduced from the third rosette leaf on, mainly because of decreased width. Cellular analysis of the abaxial epidermal cell layer of the third leaf indicated that the cell number in the mutant was similar to that of the wild type, but the cell size was significantly reduced. We postulate that the reduced cell expansion in the epidermis contributes to the narrow shape of ang3 leaves. Growth was also significantly impaired in hypocotyls and primary roots, hinting at a general role for RPL5B in organ growth, unrelated to dorsiventral axis formation. Comparison of the transcriptome of the shoot apices of the mutant and the wild type revealed a limited number of differentially expressed genes, such as MYB23 and MYB5, of which the lower expression in the ang3 mutant correlated with reduced trichome density. Our data suggest that translation is an important level of control of growth and development in plants.
Van Minnebruggen
Annemie
A
Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), Gent, Belgium.
Neyt
Pia
P
De Groeve
Steven
S
Coussens
Griet
G
Ponce
María Rosa
MR
Micol
José Luis
JL
Van Lijsebettens
Mieke
M
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D049108:Cell Enlargement; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000166:cytology* / Q000254:growth & development; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA
D029681:Arabidopsis Proteins; D012269:Ribosomal Proteins