Group of Víctor Quesada and Pedro Robles

RESEARCH SUMMARY

We are performing in our laboratories a reverse genetic approach to identify and characterize Arabidopsis thaliana mutants affected in nuclear genes coding for proteins involved in the flow of genetic information in chloroplasts and mitochondria. For most of the studied genes, there have not been hitherto described any mutant phenotype resulting from impaired function. We are focused in two protein families: the mitochondrial transcription termination factors (mTERFs), and the chloroplast and mitochondrial ribosomal proteins (respectively cpRPs and mtRPs). Our main goal is to shed light on the understanding of the functions of mTERFs, cpRPs and MRPs in plant growth, development and adaptation to abiotic stress, especially to salinity. 

RESEARCH LINES

Line 1: Genetic and molecular characterization of the Arabidopsis thaliana mitochondrial transcription termination factors (mTERFs)

The mTERF factors are coded by nuclear genes and in plants they carry out their functions in chloroplasts and mitochondria, where they are required for appropriate organellar gene expression. Land plant genomes include a much higher numbers of mTERF genes than animals. However, only a few of them have been molecularly characterized through the analysis of loss-of-function mutants. We are performing in our laboratories a phenotypic, genetic and molecular characterization of several Arabidopsis mterf mutants (e.g., mda1/mterf5, mterf6 and mterf9) which show different perturbations in growth and development, as well as an altered response to abiotic stress.

The mterf6 mutants (in red) are more sensitive to salinity stress (150 mM NaCl) than the wild-type Columbia-0 (Col-0; in blue) during germination and seedling establishment (a-d panels). Additionally, the mterf6-5 mutant shows growth, vegetative and reproductive developmental alterations (A-G panels on the right).

Line 2: Functional analysis of chloroplast and mitochondrial ribosomal proteins in Arabidopsis thaliana

Ribosomes, made of RNAs and proteins, are the molecular machinery that translate messenger RNAs in prokaryotes as well as and in the cytoplasm, chloroplasts and mitochondria of eukaryotic cells. With the aim of increasing the understanding of the functions of chloroplast and mitochondrial ribosomal proteins (respectively cpRPs and MRPs) in plants, we have initiated a reverse genetic approach to identify and characterize mutants affected in this kind of proteins in the plant model system Arabidopsis thaliana. We have identified mutant alleles carrying a T-DNA insertion in nuclear genes coding cpRPs or MRPs for which any loss-of-function viable alleles have been hitherto described. Currently we are characterizing these mutant at the phenotypic, genetic and molecular levels.

Rosette phenotypes of mutants affected in nuclear genes encoding chloroplast (upper panel) or mitochondrial (lower panel) ribosomal proteins. In the upper left corner it is shown a picture of the wild-type Columbia-0, the genetic background of all these mutants.