Microsatellite markers for genome analysis in Brassica. I. development in Brassica napus and abundance in Brassicaceae species

One hundred and twenty one microsatellites were identified by screening a l ambda phage library of Brassica napus. The distribution of these microsatel lites within Brassicaceae species was estimated using 81 locus-specific pri mer pairs. Most of them (83%) amplified fragments either from Brassica oler acea or Brassica campestris, or from both species, whereas less than 30% de tected loci in Brassica nigra. The same was true (30-35%) for more-distantl y related crucifer species such as Diplotaxis ssp., Brassica tournefortii, Sinapis alba, Raphanus sativus and Eruca sativa. Only 16 microsatellite-spe cific primer pairs (19.8%) amplified fragments from Arabidopsis thaliana. M oreover, 61 of the primer pairs detecting 198 polymorphisms were used to es timate the extent of genetic diversity among 32 Brassica napus varieties an d breeding lines. On average, four alleles per locus were observed. The spr ing and winter types of oilseed rape could be clearly distinguished by usin g the microsatellite markers in a cluster analysis. The results demonstrate d the high efficiency of these markers for monitoring genetic diversity.