1. Interspecific reproductive barriers between sympatric populations of wild tomato species (Solanum section Lycopersicon).
- Author
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Baek YS, Royer SM, Broz AK, Covey PA, López-Casado G, Nuñez R, Kear PJ, Bonierbale M, Orillo M, van der Knaap E, Stack SM, McClure B, Chetelat RT, and Bedinger PA
- Subjects
- Flowers genetics, Flowers growth & development, Flowers physiology, Fruit genetics, Fruit growth & development, Fruit physiology, Geography, Hybridization, Genetic, Peru, Pollen genetics, Pollen growth & development, Pollen physiology, Pollen Tube genetics, Pollen Tube growth & development, Pollen Tube physiology, Pollination, Reproduction, Seeds genetics, Seeds growth & development, Seeds physiology, Self-Incompatibility in Flowering Plants, Solanum genetics, Solanum growth & development, Sympatry, Solanum physiology
- Abstract
Premise of the Study: Interspecific reproductive barriers (IRBs) often prevent hybridization between closely related species in sympatry. In the tomato clade (Solanum section Lycopersicon), interspecific interactions between natural sympatric populations have not been evaluated previously. In this study, we assessed IRBs between members of the tomato clade from nine sympatric sites in Peru., Methods: Coflowering was assessed at sympatric sites in Peru. Using previously collected seeds from sympatric sites in Peru, we evaluated premating prezygotic (floral morphology), postmating prezygotic (pollen-tube growth), and postzygotic barriers (fruit and seed development) between sympatric species in common gardens. Pollen-tube growth and seed development were examined in reciprocal crosses between sympatric species., Key Results: We confirmed coflowering of sympatric species at five sites in Peru. We found three types of postmating prezygotic IRBs during pollen-pistil interactions: (1) unilateral pollen-tube rejection between pistils of self-incompatible species and pollen of self-compatible species; (2) potential conspecific pollen precedence in a cross between two self-incompatible species; and (3) failure of pollen tubes to target ovules. In addition, we found strong postzygotic IRBs that prevented normal seed development in 11 interspecific crosses, resulting in seed-like structures containing globular embryos and aborted endosperm and, in some cases, overgrown endothelium. Viable seed and F
1 hybrid plants were recovered from three of 19 interspecific crosses., Conclusions: We have identified diverse prezygotic and postzygotic IRBs that would prevent hybridization between sympatric wild tomato species, but interspecific hybridization is possible in a few cases., (© 2016 Botanical Society of America.) more...- Published
- 2016
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