Abstract
The contribution of organellar genomes (mitochondrial, mt and plastid, pt) to fitness and local adaptation of plants is well documented. However, neither the genetic variations involved, both in cytoplasmic and nuclear genomes, have been identified, nor the extent of phenotype variation they confer to adaptive evolution has been evaluated. Moreover, very little knowledge is available about the molecular and physiological integration into the global plant phenotype, such as fitness, of natural genetic variation at the level of organelle genes. In addition, nuclear-cytoplasmic co-adaptation exerts evolutionary constraints on genetic variations in both compartments that are not fully understood. /nIn this project, focused on the model species Arabidopsis thaliana, we will address adaptation at two interdependent levels: the contribution of cytoplasmic variations to plant adaptation to its environment; the co-adaptation of the cytoplasmic and nuclear genetic compartments. We recently described cytoplasmic diversity in a collection of accessions from diverse geographic origins and showed that nucleo-cytoplasmic co-adaptation exists inside the diversity of the species (Moison et al, 2010, Plant J 63:728-38). In addition, genetic variations correlated with adaptation to climatic variables have been recently described for this species (Hancock et al, 2011, Science 34:83-86; Fournier-Level et al, 2011, Science 34:86-89). Interestingly, biological processes related to pt or mt activities, such as photosynthesis and energy metabolism were found to be enriched in the correlated polymorphisms (Hancock et al, 2011). Finally, potentially adaptive traits, such as water use efficiency (WUE), seed dormancy and germination, were impacted in this species by cytoplasmic variations (McKay et al, 2008, Evolution 62:3014-26; Corey et al, 1976, Genetics 82:677-83; our unpublished work). /nThis project will take advantage of a novel genetic resource: 56 cytolines (lines possessing the nuclear genome of an accession and mt and pt genomes of another) produced from the smallest core-collection (n=8) of the Versailles Arabidopsis Stock Centre (VASC) (McKhann et al, 2004, Plant J 38:193-202). These new genetic combinations will be used to: /n1. Identify nuclear and cytoplasmic genes involved in cyto-nuclear co-adaptation in A. thaliana. This will exploit a combination of organelle and nuclear genomes leading to male sterility. /n2. Evaluate the impact on phenotype of the new genetic combinations, at different levels, for potentially adaptive traits. /n3. Correlate measured variable traits at different phenotypic levels /n4. Identify genomic regions in the different genetic compartments likely involved in plant adaptation and/or cyto-nuclear co-adaptation /n
France