Characterization of plant germplasm using molecular techniques is playing an increasingly important role in the management and utilization of plant genetic resources, but has its limitations in the screening of large numbers of accessions held in seed genebanks worldwide. Bulking individual plants from one accession or group to form a representative sample is a promising approach to widening the scope of a characterization, but it is not without technical problems in detecting genetic variation. This review was conducted to assess the technical pitfalls of bulking, and to evaluate the effectiveness of various bulking methods in the assessment of genetic variation and genetic relationships, and in the identification of plant germplasm. Clearly, some alleles, particularly those occurring at low frequency, may go undetected in a bulked sample, depending on the bulking methods and the molecular techniques used. As a result, genetic diversity estimates and genetic relationship inferences can be significantly biased. Germplasm identification may not be always reliable. Thus, it is imperative that the detection limit imposed by bulking be assessed for a newly initiated molecular germplasm characterization and bias be considered in interpretation of the resulting characterization data. Equally imperative is the need for continuous efforts of exploring efficient bulking procedures for the screening of large germplasm collections, particularly by the newly developed marker systems.

The perception by arable farmers in the UK of research organizations and companies acting as sources of information relating to plant genetic resource utilization is represented using brand strength plots. In development situations there exist considerable difficulties in achieving technology transfer. The method of brand analysis applied in this paper could be extended to characterize options in the selection of vectors for technology transfer in development programmes. A survey of potential vectors such as television, radio, extension services, univer- sities, government agencies and commercial companies would reveal their comparative brand strength and hence utility for achieving development objectives.

We have compared the genetic diversity of 24 Chinese weak-winter, Swedish winter and spring Brassica napus accessions by inter-simple sequence repeats (ISSRs). Using cluster analysis (UPGMA) based on 125 polymorphism bands amplified with 20 primers, the 24 accessions were divided into three groups. Six Swedish winter lines and eight Chinese weak-winter lines were in group I and group II consisted of two Chinese weak-winter lines, Xiangyou15 and Bao81. The third group contained eight Swedish spring lines. Principal coordinates (PCO) analysis showed similar groupings to cluster analysis. Results from cluster analysis and PCO analysis showed very clearly that Chinese weak-winter, Swedish spring and winter accessions were distinguished from each other and Chinese weak-winter accessions in this study were genetically closer to Swedish winter accessions than to Swedish spring accessions. The Chinese weak-winter accessions had larger diversity than the Swedish spring or winter accessions. This study indicated that ISSR is a suitable and effective tool to evaluate genetic diversity among rapeseed germplasm.

A set of 146 representative adzuki (Vigna angularis var. angularis and var. nipponensis) germplasm from six Asian countries with a tradition of adzuki bean production, together with an outgroup standard rice bean (Vigna umbellata), were analysed by amplified fragment length polymorphism (AFLP) methodology using 12 informative primer pairs. A total of 313 unambiguous polymorphic bands were created. According to the dendrogram, using cluster analysis based on AFLP banding, 143 of the accessions were distinct and revealed enough genetic diversity for identification and classification of accessions within Vigna angularis. A neighbour-joining tree was generated using the newly developed Innan's nucleotide diversity estimate from the AFLP data. From analysis, seven distinct evolutionary groups, named ‘Chinese cultivated’, ‘Japanese cultivated’, ‘Japanese complex-Korean cultivated’, ‘Chinese wild’, ‘China Taiwan wild’, ‘Nepal- Bhutan cultivated’ and ‘Himalayan wild’, were detected. Nucleotide diversity with geographical distribution of each group is discussed, regarding the evolutionary relationships between wild and cultivated adzuki beans. The preliminary results indicated that cultivated adzuki beans have been domesticated from at least four progenitors with at least three geographical origins.