Abstract
In this study, we investigated the genetic diversity of a collection of 136 Medicago truncatula lines from 10 Tunisian natural populations collected in well-defined locations and in various ecological conditions of soil, salinity and water availability. The genetic diversity was evaluated using a set of 18 microsatellites (SSRs), representing the 8 chromosomes of M. truncatula. A neutrality test showed that 7 SSRs were non-neutral with evidence of balancing selection. The 11 neutral SSRs revealed a geographical pooling with the Tunisian Dorsale axis restricting migration of alleles. The 7 non-neutral alleles demonstrate a correlation with rainfall, altitude and salinity environmental variables suggesting that these SSRs are linked to genes involved in water use efficiency, resistance to salinity or adaptation to altitude, and that there is local adaptation of M. truncatula to these variables. This demonstrates that the choice of so-called neutral markers should be carefully evaluated in population genetic studies. This study illustrates the genetic diversity occurring in natural Tunisian populations of M. truncatula and describes the first collection of this species dedicated to natural variation involved in adaptation to the environment.
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Acknowledgments
This research was supported in part by French-Tunisian cooperation (CMCU 00F0909, PICS 712) and by European Union (FP6 Integrated Project “Grain Legumes”). F.L. was recipient of a PED grant thesis by CNRS. F.C. was supported by a grant from the FP6 European Integrated Project “Grain Legumes”. The authors thank Dr. S. Santoni (INRA, Montpellier, France) for his generous gift of SSRs markers. We thank an anonymous reviewer for his/her precious advices to improve the manuscript. We thank M. Friesen (UC Davis, USA) for reading the manuscript before publication.
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F. Lazrek and V. Roussel contributed equally to this work.
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Lazrek, F., Roussel, V., Ronfort, J. et al. The use of neutral and non-neutral SSRs to analyse the genetic structure of a Tunisian collection of Medicago truncatula lines and to reveal associations with eco-environmental variables. Genetica 135, 391–402 (2009). https://doi.org/10.1007/s10709-008-9285-3
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DOI: https://doi.org/10.1007/s10709-008-9285-3