Phenotypic characterization and reaction norms of Arabidopsis thaliana accessions by means of transplant experiments between contrasting environments (REACT)

Spanish National Plan for R+D+i (CGL2012-33220/BOS). PI: F.X. Picó. 2013-2015.

At present, the annual plant Arabidopsis thaliana (Arabidopsis hereafter) represents a model system for genetics but also for evolutionary ecology. This is totally supported by the species' well-known genetic attributes as well as recent studies in the fields of ecology and evolutionary ecology on natural Arabidopsis populations across its distribution range. Furthermore, the 1,001 Genome Project is going to generate whole-genome sequences of worldwide natural Arabidopsis accessions in the short term. Therefore, for the first time we can attempt to comprehensively analyse the molecular and genetic basis of adaptive variation in Arabidopsis using whole-genome data. However, there is an important limitation to achieve this goal: the lack of phenotyping of fitness-related life-cycle traits of Arabidopsis in natural environments. The main objective of this project is to bridge this gap of knowledge by conducting transplant experiments of Arabidopsis accessions between contrasting natural environments to assess adaptive phenotypic variation in life-cycle traits. Based on previous knowledge, we test the hypothesis that Arabidopsis locally adapted to environmental conditions mediated by altitude. In other words, altitude and its associated environmental conditions strongly shaped several life-cycle traits that permit the plant to perform well and thrive across contrasting natural environments. To this end, two experimental gardens in Southern Spain, El Castillejo (Grazalema, Cádiz, 350 m) and La Cortijuela (Sierra Nevada, Granada, 1650 m), that significantly differ in altitude and subsequent associated environmental conditions, are selected to conduct transplant experiments over at least two years. Experiments will include 200 non-redundant Arabidopsis accessions from the collection of Arabidopsis populations of the Iberian Peninsula generated by the PI of this project and his main collaborator (Dr. Carlos Alonso-Blanco; CNB-CSIC) since 2003. Variation in key life-cycle traits, including germination timing, vegetative growth, plant survival, flowering time, and reproductive effort will be quantified periodically at both experimental gardens. The GIS-enabled application developed in a previous granted project of this same call will be applied to investigate the environmental variation influencing the species' potential distribution range as well as the potential distribution of genetic diversity and quantitative variation in life-cycle traits. The GIS-enabled application will become a tool for the Arabidopsis community interested in natural variation to select Iberian accessions based on their ecological, environmental, genetic and phenotypic characteristics. The last goal of this project is to continue the studies on the biology and natural history of Arabidopsis populations, which are being conducted uninterruptedly since 2007. The understanding and interpretation of field ecological and genetic data provides the knowledge needed to pose realistic hypotheses, design the most appropriate experiments to answer different questions, and contextualize the results and their interpretation in their adequate theoretical framework.