Microsatellite polymorphism in Pisum sativum

Pisum sativum sequences were retrieved from Genbank/EMBL databases and sear ched for all possible dinucleotide and trinucleotide tandem repeats. One-hu ndred and seventy-one simple sequence repeats (SSRs) were found among 663 s equences, The different dinucleotide or trinucleotide motifs occurred,It va rying frequencies. CT/AG was the most frequent dinucleotide, and TCT/AGA th e most frequent trinucleotide. Forty-three microsatellite markers were gene rated from these sequences and used to assess the genetic variability among 12 pea genotypes. Thirty-one were polymorphic among the genotypes and the average number of variants per marker was 3.6 when considering only polymor phic markers. Overall, the number of variants for a given SSR marker was co rrelated with the length of the SSR but some 12-bp long SSRs showed the sam e degree of polymorphism as longer ones. The groupings resulting from the S SR genotyping among the 12 genotypes gave an interesting insight into the p ossible origin of one recent cultivar. Database-derived SSR markers are hig hly variable. They can provide useful information on the genetic diversity among P. sativum cultivated types.