You Soon Baek1, Suzanne M Royer1, Amanda K Broz1, Paul A Covey1, Gloria López-Casado2, Reynaldo Nuñez3, Philip J Kear4, Merideth Bonierbale4, Matilde Orillo4, Esther van der Knaap3,5, Stephen M Stack1, Bruce McClure6, Roger T Chetelat7, Patricia A Bedinger8. 1. Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA. 2. Department of Plant Biology, Cornell University, Ithaca, New York 14853, USA. 3. Department of Horticulture and Crop Science, Ohio State University, Wooster, Ohio 44691, USA. 4. Quality and Nutrition Laboratory, Centro Internacional de la Papa, Perú Postal 1558, Lima, Peru. 5. Department of Horticulture, University of Georgia, Athens, Georgia 30602, USA. 6. Department of Biochemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA. 7. Department of Plant Sciences, University of California Davis, Davis, California 95616, USA. 8. Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA bedinger@colostate.edu.
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 F1 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.
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 F1 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.
Authors: Miguel A Flores-Vergara; Elen Oneal; Mario Costa; Gonzalo Villarino; Caitlyn Roberts; Maria Angels De Luis Balaguer; Sílvia Coimbra; John Willis; Robert G Franks Journal: Front Plant Sci Date: 2020-02-25 Impact factor: 5.753
Authors: A Lovisa S Gustafsson; Galina Gussarova; Liv Borgen; Hajime Ikeda; Alexandre Antonelli; Lucas Marie-Orleach; Loren H Rieseberg; Christian Brochmann Journal: Ann Bot Date: 2022-01-28 Impact factor: 4.357