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 lambda phage library of Brassica napus. The distribution of these microsatellites within Brassicaceae species was estimated using 81 locus-specific primer pairs. Most of them (83%) amplified fragments either from Brassica oleracea or Brassica campestris, or from both species, whereas less than 30% detected loci in Brassica nigra. The same was true (30-35%) for more-distantly related crucifer species such as Diplotaxis ssp., Brassica tournefortii, Sinapis alba, Raphanus sativus and Eruca sativa. Only 16 microsatellite-specific primer pairs (19.8%) amplified fragments from Arabidopsis thaliana. Moreover, 61 of the primer pairs detecting 198 polymorphisms were used to estimate the extent of genetic diversity among 32 Brassica napus varieties and breeding lines. On average, four alleles per locus were observed. The spring and winter types of oilseed rape could be clearly distinguished by using the microsatellite markers in a cluster analysis. The results demonstrated the high efficiency of these markers for monitoring genetic diversity.