Genetic and molecular analysis of growth responses to environmental factors using Arabidopsis thaliana natural variation

Arabidopsis thaliana natural accessions have been collected in the Northern hemisphere in a wide range of habitats, with a specific environment in each habitat, suggesting that selection for adaptation to these local environments occurred and provided genetic variation of responses to environmental factors. Plant performance traits are complex traits and are fluctuating under contrasted environmental conditions (e.g., temperature, day length, nutrient nutrition, drought). The genetic architecture of such traits and of their responses to environmental conditions could be analysed by detecting QTL (Quantitative Traits Loci). Accessions from contrasted geographical regions have been used to detect such QTL. QTL analysis and subsequent QTL cloning of genetic variation for growth and plant performance traits in Arabidopsis using Arabidopsis thaliana natural accessions are powerful tools to understand the genetic and the molecular basis of plant performance in contrasted environments. QTL analysis of growth-related traits and their response to temperature, light and nutrient starvation in hydroponic system are in progress in different populations (recombinant inbred lines, backcross inbred-line populations) Near-isogenic lines or heterogeneous inbred lines are also selected and used to confirm the effect of QTL and to isolate recombinant events in the QTL region in order to fine-map and clone the QTL. The challenge of these studies is to understand this genetic variation, which is also very relevant for plant breeding, since it involves the traits determining yield and yield stability. It is difficult to predict which processes underlie this genetic variation, but candidate processes are primary and secondary metabolism, nutrient uptake, transport processes and aspects of development etc. This implies that a thorough and broad (whole plant) approach needs to be applied to identify the nature of the observed variation. Apart from being relevant for breeding it is assumed that genetic variation for plant performances contributes to the adaptation of specific genotypes to a specific ecological system and therefore has ecological and evolutionary relevance.