Mapped SSR markers unevenly distributed on the cotton chromosomes

Abstract

In the past 15 years, more than 9000 SSR markers have been developed, which are a valuable resource for cotton genetics and breeding. Many of them have been mapped in cotton, and several high-density genetic maps have been constructed. In this paper, we jointly analyzed the mapped SSRs to characterize their motifs on cotton chromosomes. The results showed that SSR loci were distributed unevenly on cotton chromosomes with more on C11 and C19 and less on C02 and C04. Different sources of SSRs contributed different predominant SSR types, which were also distributed unequally on cotton chromosomes. Compared to SSRs derived from enriched libraries and BAC end sequences, EST-SSRs could generate novel SSR motifs especially for AT/TA of di-, tetra-, penta- and hexanucleotide. SSR motifs showed a biased distribution on cotton chromosomes with more on C05, C11, and C19, and less on C02 and C04. The uneven distribution of SSRs on cotton chromosomes would help us to enrich the cotton genetic map by motif-specific SSRs. This analysis gave us new knowledge on the architecture of the cotton genome.

Key words： cotton; SSR; motif; genetic linkage map