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Molecular Markers associated with Cotton Cytoplasmic Male Sterility Restorer Gene Rf1

Chunda Feng, Jinfa Zhang and James McD. Stewart


ABSTRACT

Molecular marker assisted selection (MAS) can accelerate the process of plant breeding. Sequence tagged site (STS) markers are more suitable than most types of molecular markers for MAS. The objective of this research is to develop STS markers tightly linked with Rf1, the fertility-restoring gene for cytoplasmic male sterility in cotton. Bulked segregate analysis (BAS) was conducted to screen for Rf1-linked RAPD markers with 300 10-mer random primers on a 114-individual backcross population (B416R X Ark8518) X Ark 8518. Four RAPD markers were found, among which three markers co-segregated with Rf1 and one co-dominant marker segregated 4.5cM from Rf1. The two homologous bands from this last primer demonstrated repulsion linkage. A previously reported marker was 2.7cM from Rf1 and 1.8 cM from the co-dominant marker. Three pairs of STS primers were designed based on the sequences of the three co-segregating RAPD markers. Both Rf1STS- 1400 and Rf1STS-500 primer pairs amplified a single band present in fertile plants and absent in sterile plants. The Rf1STS- 700 primer pair amplified a band from fertile plants that was derived from G. harknessii, and a monomorphic band from all plants that was derived from the A subgenome. These two bands were homologs. The three Rf1 STS markers were present in G. harknessii, the donor species of Rf1. G. trilobum also contained three STS fragments but the fragment amplified by the Rf1STS-1400 primers was larger than that from G. harknessii. Some species of the D genome yielded only two fragments with the primer pairs. Sequence analysis suggested that Rf1STS-1400 contains an initial exon, Rf1STS-500 contains an internal exon, and Rf1STS-700 contains a terminal exon. These STS markers will be useful in breeding parental R lines for cotton CMS fertility restoration.





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Document last modified May 20, 2002