ARS | Publication request: Identification of SSR Markers Linked to the Gametophytic Self-Incompatibility Locus in Red Clover (Trifolium pratense)

Submitted to: International Symposium of Molecular Breeding of Forage Turf
Publication Type: Proceedings
Publication Acceptance Date: January 20, 2010
Publication Date: March 15, 2010
Citation: Riday, H., Krohn, A.L. 2010. Identification of SSR Markers Linked to the Gametophytic Self-Incompatibility Locus in Red Clover (Trifolium pratense). In: Proceedings of the 6th International Symposium of Molecular Breeding of Forage Turf. p. 191.

Technical Abstract: Self-pollination is prevented in red clover by a gametophytic self-incompatibility system (SI). This SI system is likely controlled by two tightly linked genes, effectively creating a single locus. While SI genes have been identified in some plants, they have not been identified in red clover or other Fabaceae. Too identify the SI-Locus two mapping populations were developed. The first was a single-cross between a S1S2 and a S2S3 plant. From each maternal plant, 50 progeny were grown to maturity with maternal identity maintained. S-locus genotypes were identified using testcrosses within maternal progeny groups. SSR (Sato et al., 2005) co-segregating with progeny genotypes and pollen haplotype within maternal progeny groups were identified. Approximately 200 haplotypes were mapped. The second mapping population was a cross between a heterozygous self-compatible dominant mutant (SfSx) and a wild-type plant (SxSx). Attempted progeny self-pollination determined genotype. SSR co-segregating with progeny genotypes were identified. 240 progeny were used. In both mapping populations the SI-locus mapped to a position on LG1 approximately 1cM down from RCS5615. Other closely linked markers include: RCS5027, RCS6958, RCS3161, RCS0810, and RCS0907. This confirms the tested self-compatible mutant is a SI-locus mutant. The linked SSR are being used to identify S-alleles in breeding programs to: 1) enhance paternity testing and 2) create S-allele restricted populations increasing population hybridity (Riday and Krohn, 2010). Sato, S., S. Isobe, E. Asamizu, N. Ohmido, R. Kataoka, K. Nakamura, T. Kaneko, N. Sakurai, K. Okumura, I. Klimenko, S. Sasamoto, T. Wada, A. Watanabe, M. Kohara, T. Fujishiro, and S. Tabata. 2005. Comprehensive structural analysis of the genome of red clover (Trifolium pratense L.). DNA Res. 12:301-364. Riday, H., and A.L. Krohn. 2010. Increasing population hybridity by restricting self-incompatibility alleles in red clover populations. Crop Sci. [in press].