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Maternal effects and embryo genetics: germination and dormancy of crop–wild sunflower hybrids

  • Alexa N. Weiss (a1), Samantha B. Primer (a1), Brian A. Pace (a1) and Kristin L. Mercer (a1)


Gene flow between agricultural crops and related wild plant populations can produce hybrids which differ significantly from their wild counterparts in many life history traits, including seed traits. Seeds from wild annuals often possess significant dormancy, while cultivated varieties have been selected to germinate immediately under favourable conditions. Consequently, the dormancy characteristics of crop–wild hybrids could influence their survival, seed-bank dynamics and, ultimately, the extent to which crop genes persist in wild populations. Dormancy characteristics can be influenced by both maternal effects, as well as the genetics of a seed's embryo, which are the result of contributions from both parents. Here we focus on how maternal effects and embryo genetics affect seed dormancy in crop–wild hybrid sunflowers (Helianthus annuus). Using three laboratory experiments, we quantified the germination and dormancy of 15 crop–wild hybrid sunflower cross types, while also identifying achene characteristics that may influence the differential germination observed. We found that increased frequencies of crop alleles and the maternal effects imparted by hybridization can reduce dormancy, though the effect of increased frequencies of crop alleles was more pronounced in wild- and F1-produced than in the crop-produced achenes. The more open pericarp of the crop-produced achenes and the shorter relative distance that their radicles had to travel to germinate may explain some of the observed maternal effects. Finally, we generated hypotheses about how these results could affect survival and crop gene introgression in the field.


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