Plants (Apr 2020)

Physical Dormancy Release in <i>Medicago truncatula</i> Seeds Is Related to Environmental Variations

  • Juan Pablo Renzi,
  • Martin Duchoslav,
  • Jan Brus,
  • Iveta Hradilová,
  • Vilém Pechanec,
  • Tadeáš Václavek,
  • Jitka Machalová,
  • Karel Hron,
  • Jerome Verdier,
  • Petr Smýkal

DOI
https://doi.org/10.3390/plants9040503
Journal volume & issue
Vol. 9, no. 4
p. 503

Abstract

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Seed dormancy and timing of its release is an important developmental transition determining the survival of individuals, populations, and species in variable environments. Medicago truncatula was used as a model to study physical seed dormancy at the ecological and genetics level. The effect of alternating temperatures, as one of the causes releasing physical seed dormancy, was tested in 178 M. truncatula accessions over three years. Several coefficients of dormancy release were related to environmental variables. Dormancy varied greatly (4–100%) across accessions as well as year of experiment. We observed overall higher physical dormancy release under more alternating temperatures (35/15 °C) in comparison with less alternating ones (25/15 °C). Accessions from more arid climates released dormancy under higher experimental temperature alternations more than accessions originating from less arid environments. The plasticity of physical dormancy can probably distribute the germination through the year and act as a bet-hedging strategy in arid environments. On the other hand, a slight increase in physical dormancy was observed in accessions from environments with higher among-season temperature variation. Genome-wide association analysis identified 136 candidate genes related to secondary metabolite synthesis, hormone regulation, and modification of the cell wall. The activity of these genes might mediate seed coat permeability and, ultimately, imbibition and germination.

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