Project name: Arabidopsis thaliana

Description: 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 ANG3 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 dorsi-ventral 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.Overall design: Four hybridizations that each compare ang3 versus the control Ler-genotypes. Hybridizations were performed as 2 dye swaps with biological replicates.ang3 and Ler seedlings were sown in vitro on half-strength Murashige and Skoog medium, vernalized for 3 days and germinated at 21C and under a 16-h light regime. The green parts of stage 1.03 plants were harvested (Boyes et al. 2001), consisting of the SAM, the first and second young leaves, the third leaf larger than 1 mm, the fourth leaf smaller than 1 mm and the cotyledons. Per genotype, four replicates were harvested and per replica three repetitions. Total RNA was extracted with the RNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and the samples analyzed In the VIB MicroArrays Facility with the Agilent microarray platform. The processed Cy3 and Cy5 intensities were normalized and statistically analyzed with the Feature Extraction Software (version 10.1.1.1; Agilent Technologies, Santa Clara, CA, USA). P values had to be lower than 0.05 and the absolute value of the log2 ratio had to be higher than one. To visualize overrepresented Gene Ontology (GO) categories, upregulated and downregulated data sets were analyzed with BiNGO (Maere et al. 2005; Fleury et al. 2007).

Data type: Transcriptome or Gene expression

Sample scope: Multiisolate

Relevance: ModelOrganism

Release date: 2009-10-14

Last updated: 2009-10-09