Huo, heqiang , Peggy, Ozias-Akins .
Retrotransposon-Based Molecular Marker Development for Apomixis in Pennisetum squamulatum.
Apomixis is a mode of reproduction in flowering plants in which embryos form without fertilization of the egg. Pennisetum squamulatum reproduces by apospory, a type of apomictic reproduction where non-generative nucellar cells develop into unreduced embryo sacs. Genetic mapping of this trait showed that apospory appeared to be transmitted as a single locus, but this “locus” actually is a large chromosomal block which we named the apospory-specific genomic region (ASGR). The ASGR has been cytogenetically mapped by fluorescence in situ hybridization to a heteromorphic chromosome. The large physical size of the ASGR (>50Mb), its high hemizygosity, and an abundance of repetitive elements including LTR-retrotransposons make it inaccessible for direct sequencing under the current circumstances. Additional molecular markers are required for high resolution mapping and further characterization of the ASGR. In this study, the LTR regions of retrotransposons belonging to the family that is most abundant in the ASGR were sequenced from P. squamulatum. Sequence alignments that included family members from the sexual relative P. glaucum allowed the design of LTR-specific primers that were used for transposon display or Sequence-Specific Amplification Polymorphism (S-SAP). Both MseI/EcoRI and MseI/PstI restriction enzyme combinations were tested. Samples processed with the methylation-sensitive restriction enzyme PstI resulted in the amplification of a substantial number of new ASGR-linked markers based on segregation among individuals in an F1 population. Twenty-seven out of 96 primer combinations showed ASGR-linked polymorphisms. A few individuals that did not show recombination between apospory and previously characterized SCAR markers do show recombination with some S-SAP markers. This approach to develop new markers will be helpful to more accurately delineate the size of the ASGR.
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1 - University of Georgia Tifton Campus, Horticulture, NESPAL, 2356 Rainwater Road, Tifton, Georgia, 31794, USA
2 - University of Georgia Tifton Campus, Horticulture
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM