Amplified fragment length polymorphism (AFLP) markers were employed to assess the genetic diversity amongst two large collections of Brassica rapa accessions. Collection A consisted of 161 B. rapa accessions representing different morphotypes among the cultivated B. rapa, including traditional and modern cultivars and breeding materials from geographical locations from all over the world and two Brassica napus accessions. Collection B consisted of 96 accessions, representing mainly leafy vegetable types cultivated in China. On the basis of the AFLP data obtained, we constructed phenetic trees using MEGA 2.1: software. The level of polymorphism was very high, and it was evident that the amount of genetic variation present within the groups was often comparable to the variation between the different cultivar groups. Cluster analysis revealed groups, often with low bootstrap values, which coincided with cultivar groups. The most interesting information revealed by the phenetic trees was that different morphotypes are often more related to other morphotypes from the same region (East Asia vs. Europe) than to similar morphotypes from different regions, suggesting either an independent origin and or a long and separate domestication and breeding history in both regions.

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[12,21]. PSV is an economically important threat to peanut production in China. Severe epidemics of virus diseases caused by PSV along with Peanut stripe virus (PStV) and Cucumber mosaic virus (CMV) have substantially reduced peanut yields in the major peanut growing areas in northern China since the 1970 s [22]. In addition, disease surveys revealed that black locust trees (Robinia pseudoacacia L.), a popular tree in northern China, are widely infected by PSVThe nucleotide sequence data of RNA1, 2 and 3 of PSV-Mi have been deposited in GenBank under accession numbers AY429431, AY429430 and AY775057.