European Journal of Plant Pathology

, Volume 135, Issue 4, pp 831–843 | Cite as

Natural variation of Medicago truncatula resistance to Aphanomyces euteiches

  • Naceur Djébali
  • Souha Aribi
  • Wael Taamalli
  • Soumaya Arraouadi
  • Mohamed Elarbi Aouani
  • Mounawer Badri


We analysed the resistance variation in 14 natural populations of Medicago truncatula from Tunisia to Aphanomyces euteiches infection. The reaction of M. truncatula lines to A. euteiches infection varied from susceptibility to full resistance. Of the overall level of phenotypic variation, 65.4 % was found to occur within populations. Principal component analysis showed a high spread of lines belonging to the same population, indicating no clear structure in the Tunisian M. truncatula populations and supporting the hypothesis of gene flow among populations. Likewise, there was no association between local resistance composition and the geographical distances between populations, ruling out isolation by distance as an explanation. Furthermore, significant correlations were observed between quantitative traits and ecological factors consistent with the local adaptation hypothesis. A cluster analysis of the populations showed the presence of three groups. The first group comprised the populations originating from the centre of the country, containing the main resistant lines. The second group included the populations collected in the south and the mountain region of Thala and contained the main partially resistant lines. The third group comprised the populations sampled from the north regions and saline soils and included the main susceptible lines. Overall, we found that the natural M. truncatula lines were more likely to be susceptible (71.3 %) than resistant (28.7 %) to A. euteiches attack. Nevertheless, many resistant lines exhibiting new reaction patterns to A. euteiches attack were identified in the natural populations and these can be used for the identification of potentially new resistance genes.


Biodiversity Model legume Natural populations Oomycete pathogen Tunisia 



Coefficient of genetic variation


Day post inoculation


Principal component analysis


Level of population differentiation for quantitative traits



This work was funded by the Tunisian Ministry of Higher Education and Scientific Research. We thank Dr. Eric von Wettberg (Florida International University, USA) for a critical reading of the manuscript and the anonymous reviewers for helpful comments.


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Copyright information

© KNPV 2012

Authors and Affiliations

  • Naceur Djébali
    • 1
    • 2
  • Souha Aribi
    • 1
  • Wael Taamalli
    • 1
  • Soumaya Arraouadi
    • 1
  • Mohamed Elarbi Aouani
    • 1
  • Mounawer Badri
    • 1
  1. 1.Centre of Biotechnology of Borj CedriaHammam-LifTunisia
  2. 2.Laboratory of Molecular Physiology of PlantsCentre of Biotechnology of Borj CedriaHammam-LifTunisia

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