Evaluation of the genetic diversity among populations is an essential prerequisite for the preservation of endangered species. Thousands of new accessions are introduced into germplasm institutes each year, thereby necessitating assessment of their molecular diversity before elimination of the redundant genotypes. Of the protocols that facilitate the assessment of molecular diversity, SSRPs (simple sequence repeat polymorphisms) or microsatellite variation is the preferred system since it detects a large number of DNA polymorphisms with relatively simple technical complexity. The paucity of information on DNA sequences has limited their widespread utilization in the assessment of genetic diversity of minor or neglected crop species. However, recent advancements in DNA sequencing and PCR technologies in conjunction with sophisticated computer software have facilitated the development of SSRP markers in minor crops. This review examines the development and molecular nature of SSR markers, and their utilization in many aspects of plant genetics and ecology.

and stem, wrinkly or nonwrinkly leaves, and a fragrance specific to var. crispa. Perilla frutescens (L.) Britton var. frutescens is extensively culti-Today P. frutescens var. frutescens is extensively cultivated on a large scale throughout the Korea, whereas var. crispa is vated and used in Korea (Nitta, 2001), although cultinot. The weedy types of both var. frutescens and var. crispa are ofvated var. frutescens probably originated in China (Maten found along roadsides, waste lands, and around farmers' fields. Although Perilla is one of the important leafy vegetable and oil crops kino, 1961). In Korea, var. frutescens is used not only in Korea, systematic analyses on its genetic structure have been limited as an oil crop but also as a vegetable crop. Recently, and are needed for future breeding progress. The objective of this accompanied by increased meat consumption and develstudy was to determine genetic diversity and relatedness in Korean opment of various cooking methods of fresh leaves, var. accessions of Perilla. Field surveys and amplified fragment length frutescens became one of the most important crops in polymorphism (AFLP) analyses were conducted to determine genetic Korea. However, modern breeding methods and sysdiversity. Analyses of 30 Perilla accessions by seven AFLP primer tematic introduction of germplasm have not been praccombinations identified a total of 121 fragments, of which 72 (60%) ticed widely on this crop in Korea. No cultivars have were polymorphic at the species level. Shanon's index of diversity Hs been developed solely for production as oil or vegetaof the AFLP variations for cultivated type of var. frutescens, weedy ble crop. type of var. frutescens, and weedy type of var. crispa were 0.63, 2.00, and 1.75, respectively. The weedy type of var. frutescens exhibited

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The polygalacturonase (PG) gene family is one of the largest gene families in plants. PGs are involved in various plant development steps. The evolutionary processes accounting for the functional divergence and the specialized functions of PGs in land plants are unclear. Whole sets of PG genes were retrieved from the genome web sites of model organisms in algae and land plants. The number of PG genes was expanded by lineage-specific manner with the biological complexity of the organism. Differentiation of PGs was related with phylogenetic hierarchy such as presence of rhamno-PGs from algae to plants, endo-and exo-PGs in land plants, exo-PGs in flowering plants. Gene structure analysis revealed that land plant PG genes resulted from differential intron gain and loss, with the latter event predominating. Differential intron losses partitioned the PGs into separate clades to be expressed differentially during plant development. Intron position and phase were not conserved between PGs of algae and land plants but conserved among PG genes of land plants from moss to vascular plants, indicating that the current introns in the PGs in land plants appeared after the split between unicellular algae and multicelluar land plants. The results demonstrate that the functional divergence and differentiation of PGs in land plants is attributable to intron losses.

The numbers of SSR markers and their utilization have not been determined and investigated as extensively in Fagopyrum species as compared to other crop species. The current report presents 136 new SSR markers in Fagopyrum esculentum ssp. esculentum and their application to related species in the genus Fagopyrum. Of the 136 SSRs, 10 polymorphic SSR markers were utilized in a genetic diversity analysis of a common buckwheat population consisting of 41 accessions of diverse origin. The study showed observed (H(O)) and expected (H(E)) heterozygosities ranging from 0.071 to 0.924 (mean = 0.53) and from 0.073 to 0.902 (mean = 0.412), respectively. Forty-one of the 136 SSRs amplified sequences in other Fagopyrum species, including the cymosum and urophyllum groups. The phylogenetic relationships revealed using the SSRs was consistent with results obtained using other marker systems, with one exception. The sequence and diversity information obtained using these new SSRs and their cross-transferability to related Fagopyrum species will increase our understanding of genetic structures and species relationships within the Fagopyrum genus.

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Species of the genus Lilium are well known for their large genomes. Although expansion of noncoding repeated DNA is believed to account for this genome size, retroelement del Ty3-gypsy is the only one described so far in the genus Lilium. We isolated Ty1-copia elements from Lilium longiflorum and named them LIREs (lily retrotransposons). The long terminal repeats, primer binding site, and polypurine tract sequences are highly similar among the LIRE elements, indicating that they are in the same lineage. Although the protein-coding regions were highly decayed, the sequence motifs of the integrase, reverse transcriptase, and RNase H domains were identifiable as belonging to the order of Ty1-copia elements. Phylogenetic analysis and primer binding site sequences revealed that these elements belonged to the Ale lineage among the six lineages of plant Ty1-copia elements. Base substitutions in the long terminal repeats estimated that the integration times of the LIRE Ty1-copia elements were between 0.7 and 5.5 mya. In situ hybridization showed that the LIRE elements were present in all the chromosomes of L. longiflorum and L. lancifolium, but absent in centromeres, telomeres, and 45S rRNA sites in both species. The LIRE elements were present very abundantly in species of the genus Lilium, but absent in other genera of the family Liliaceae, implying that the LIRE elements might have contributed to the expansion of the genome in the genus Lilium.

Genetic diversity and differentiation among the wild soybeans, Glycine soja, collected from riversides of five major rivers in Korea have been analyzed with simple sequence repeat variations. When the genetic diversity in this study was compared to those of cultivated soybeans reported by others, the wild soybeans showed significantly higher genetic diversity and differentiation than those of cultivated soybeans. The number of alleles observed in this study varied from a low of 9 to high of 14 and 82 different alleles were observed among the 57 wild soybeans at seven SSR loci. The genetic diversity measured by the number of effective alleles also varied from 4.8 to 9.1 with an average of 6.8. When the genetic diversity was converted to population differentiation, the SSR alleles showed 0.8 to 0.89 depending on the SSR locus with an average of 0.86. There was no predominantly present allele (or alleles) to specific sub population. Although the highest genetic diversity was observed in the subpopulation from Nakdong river, the subpopulation from Sumjin river showed the highest genetic differentiation value. In the phenetic relationship analysis, the 57 wild soybeans were differentiated at the genetic similarity of 0.83. Since the clustering pattern did not correspond with the geographical origins where they collected, the genetic diversity and differentiation of the wild soybeans could predate the dispersal of the wild soybeans along the rivers.