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Haïfa University (2013)

Ecological genomics of pruductive fitness in wild barley

Hubner, Sariel

Titre : Ecological genomics of pruductive fitness in wild barley

Auteur : Hubner, Sariel

Etablissement de soutenance : Haïfa University

Grade : Doctor of Philosophy (PhD) 2013

MAIN GOALS AND OBJECTIVES
The main objective of this research is to study patterns of plant genetic adaptation to its environment as a central step in the process of adaptive differentiation within a species. More specifically, I suggest that the population structure of wild barley in Israel has been largely affected by both demographic and natural selection processes, thereby producing genetic architecture that contributes to plant reproductive fitness in response to spatial variation of environmental conditions, especially precipitation gradient. In accordance with this hypothesis I conducted this research following three major steps : 1. Studying patterns of genetic differentiation in wild barley. The population structure and our ability to detect it are highly affected by gene flow between wild and cultivated barley and among wild barley populations. The goals of this study are to : (i) Estimate empirically the rates and direction of gene flow between wild and cultivated barley and between natural populations of wild barley. (ii) Investigate theoretically and empirically the effect of genetic marker type, i.e. microsatellites and SNPs, on population parameter estimates. (iii) Unravel the effect of immigrants on the inference of population structure. (iv) Present a general model for gene flow between wild and cultivated barley and draw the distribution map of wild barley in Israel. 2. Studying patterns of adaptive differentiation based on quantitative traits. The differentiation of populations on the phenotypic level is expected to correspond with the ecogeographical distribution. Nevertheless, patterns of differentiation in specific traits may amend from the general patterns of divergence. In particular, I study : i) the phenotypic distribution of wild barley along environmental gradients in Israel, ii) the genetic and phenotypic divergence between ecotypes in order to distinguish between adaptive and non-adaptive patterns of differentiation, and iii) the phenotypic divergence between wild and cultivated barley. 3. Studying reproductive fitness in response to drought stress as a key trait in the process of plant adaptation. In order to investigate reproductive adaptation, candidate genes that are associated with the response to drought should be detected using drought tolerant and sensitive accessions from different regions in Israel. Four main challenging steps are followed in this study : (i) discriminate between drought tolerant and sensitive accessions based on a measurement of reproductive success under unfavorable conditions, (ii) assemble de novo wild barley RNA-Seq reads to contigs and map assembled contigs to genes, (iii) investigate the differential response of tolerant and sensitive accessions to drought treatment, and the biochemical and physiological processes that are in the basis of drought-tolerant reproductive development, and (iv) test and describe the correlation between reproductive fitness and environmental gradients.

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