Bingham, Edwin T. , Armour, David J. , Irwin, John A. G. , Jayaraman, Dhileepkumar , Ane, Jean-Michel .
Weakening the Hybridization Barrier between Herbaceous Medicago sativa and Woody M. arborea.
Medicago sativa (L.) alfalfa or lucerne, is a forage grown around the world. M. arborea is a woody shrub native to the islands and areas around the Mediterranean Sea. It can grow to a height of 4 meters; it is remarkably drought resistant, and is the longest-lived Medicago species. Our interest is in genome relationships of perennial Medicago species, and transfer of traits from M. arborea to M. sativa. In particular, we are interested in large seeds, longevity, disease resistance, and morphological traits that may be useful in restructuring alfalfa. The hybridization barrier between M. sativa and M. arborea (both tetraploids) is postzygotic endosperm/embryo failure. In 1998 we began screening for M. sativa genotypes that supported degrees of embryo development, and in 2003, a genotype (MBms) was discovered that produced 12 seeds/progeny after ca 2000 flowers pollinated by hand with M. arborea pollen. One plant was a maternal haploid, one was a self progeny, and ten exhibited hybrid characteristics. The ten varied widely in flower color, fertility and morphology. To test the repeatability of sexual hybridization, seed of MBms X ‘P’ (both parents from alfalfa cultivars) was sent to Australia  where five asymmetric hybrids were obtained in 2006. In 2007 at Wisconsin, another genotype (M8) produced ten hybrid progeny from only 500 flowers pollinated. M8 is derived from crosses involving M. sativa sensu lato subspecies sativa, coerulea, and falcata. The subspecies derivatives including M8, have outbreeding depression of fertility that may have weakened the hybridization barrier between M. sativa s.l. and M. arborea. M. arborea-specific DNA markers, flower color, and morphological traits all indicate transfer of M. arborea germ plasm to M. sativa. Genotype M8 is being tested as a bridge-cross parent in interspecific crosses of other Medicago species.
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Medicago Genetics Reports
1 - University of Wisconsin, Agronomy , 1575 Linden Drive, Madison, WI, 53706, USA
2 - The University of Queensland, School of Integrated Biology, Brisbane, Queensland, Australia
3 - University of Wisconsin Madison, Agronomy, 348 Moore Hall, 1575 Linden Drive, Madison, WI, 53706, USA
Interspecific gene transfer
Presentation Type: Poster:Posters for Topics
Location: Event Tent/Cliff Lodge
Date: Tuesday, July 28th, 2009
Time: 5:30 PM