Establishment of sorghum ESTSSR marker andits preliminary application to sudangrass

Total 202 325 Sorghum bicolor ESTs were downloaded from NCBI EST database. 6 663 SSRs loci within 5 661 ESTs were found out, and the emergence frequency was 20.19%, with the average distribution frequency of 1/3.93 kb. 3 446 (66.3%) from 5 197 ESTs could be used to design primers. Trinucleotide repeat was found to be the dominant type and GGC/GCC were the most frequent motifs in sorghum ESTSSRs. 20 pairs of primers were selected to design. Using sudangrass 722 and sorghum TX623A as templates, all the designed primers could be used to amplify the target sequences, and the usable rate was 100%, in which 4 pairs of primers were discrepant, and the polymorphism rate was 20%. Our results indicated that it was an effective and feasible approach to develop SSR markers based on sorghum ESTs.