AFLP-based genetic diversity assessment amongst agronomically important natural and some newly synthesized lines of Brassica juncea

AFLP markers were employed to assess the genetic diversity amongst 21 estab lished natural and nine synthetic varietes and lines of Brassica juncea ori ginating from Asia, Australia, Canada, Eastern Europe and Russia. Six of th e synthetics used for diversity studies have been developed recently. Twent y one EcoRI/MseI-based AFLP primer pairs generated a total of 1251 scorable fragments among the 30 genotypes studied, of which 778 bands were polymorp hic with an average of 37 polymorphic bands per primer pair. On the basis o f the similarity coefficients (F value), cluster analysis was performed usi ng the UPGMA method. The 30 B. juncea lines could be grouped into three dis tinct clusters. All the Indian, Chinese and previously developed synthetics formed one cluster (cluster A), the recently developed synthetics formed a separate cluster (cluster B) and the lines from Australia, Canada, Eastern Europe and Russia formed the third cluster (cluster C). A majority of the lines were uniquely identified by one or more primer pairs due to the prese nce or absence of variety specific band(s). Four primer pairs were found to be most informative, since these uniquely identified all the genotypes ass ayed. These four primer pairs, could therefore be used as fingerprinting pr imers for varietal identification.