GENETIC DIVERSITY IN MUSTARD (BRASSICA-JUNCEA L.) GERMPLASM FROM PAKISTAN AS DETERMINED BY RAPDS

The genetic diversity and the relationships among a collection of must ard (B. juncea) germplasm, including 41 accessions collected from Paki stan, 6 oilseed cultivars/lines and 5 Japanese vegetable cultivars, we re evaluated using random amplified polymorphic DNA (RAPD) markers. A total of 198 polymorphic amplified products were obtained from 30 deca mer primers. Of these, 14 were unique to the accession PAK-85835 and 3 7 were specific to PAK-85839. Based on pair-wise comparisons of RAPD a mplification products, genetic similarity was estimated using similari ty coefficients of Nei & Li (1979) and a dendrogram was constructed us ing the unweighted pair-group method with arithmetic averages (UPGMA). Cluster analysis based on these genetic similarities placed most of t he collected germplasm and oilseed cultivars/lines close to each other , showing a low level of polymorphism between the oilseed accessions c ollected in Pakistan. However, the clusters formed by the oilseed coll ections and cultivars were distinct from those formed by the vegetable cultivars. A low level of genetic variability of oilseed mustard in P akistan was attributed to the selection for similar traits and horticu ltural uses. The farmers' preference for more remunerative crops and p erhaps the close parentage of these accessions further contributed tow ards their little diversity. The study demonstrated that the RAPD is a simple and fast technique to compare the genetic relationships and th e patterns of variation among accessions of this crop.