| In this study, the procedure suitable for rapid soybean AFLP (amplified fragment length polymorphism) analysis was established. By using this procedure, the fingerprints of representative accessions of soybean ~re observed, and their feasibility in accession and species identification was confirmed. Combined with the data from cytoplasmic RFLP (restriction fragment length polymorphism) analysis, the genetic diversity and differentiation among various ecotypes was evaluated, and the evolutionary relationship was deduced. In the meantime, morphological and agronomic traits of various ecotypes were investigated. 1. Establishment of the procedure for rapid soybean AFLP analysis Based on the method of McDonald Ct al. (1994), the method of DNA extraction from soybean dry seeds was improved, the advantage of silver-staining in AFLP analysis was confirmed in comparison with isotope labeling, and the endoeiuynie and primer combinations suitable for AFLP analysis in soybean were screened out. Therefore, the rapid AFLP procedure for soybean accession appraisal was established. Without any risk of hazard from isotope, the silver-staining AFLP fingerprints with high resolution and good reproducibility could be obtained in two to three days from dry soybean seeds, and therefore, the technique could be utilized for soybean fingerprint analysis. 2. Efficiency of soybean fingerprinting with AFLP silver-staining method The fingerprints of ninety two representative accessions of G.soja and G.max were established by using seventeen pairs of prinier combinations selected from 218 pairs of Mse I and EcoR I which was screened out from four endoenzyme combinations. The average identification rate of 17 pairs of primer combinations was 68.54%, and the primer combination M-GGA/E-CGA could identify all the accessions tested, M-CTC/E-ACT, M-GQA/E-GGC and M-CTCIE-CGA could distinguish more than ninety percent of the accessions. Thus, all accessions could be identified with certain band combinations or characteristic bands. Compared with G.soja, less efficiency in G.max identification was found for the same primer combination. It was found that the total numbers of bands detected in G.soja and G.max were similar, but more polymorphic bands, higher polymorphic percentage and genetic diversity coefficients were observed in G.soja. Consequently, greater genetic variation was existed in G.soja. 3. Genetic grouping of G.soja and G.max accessions and species identification with AFLP molecular markers Based on simple matching coefficients calculated from the 348 polymorphic bands of 17 pairs of combinations, the genetic relationship among the accessions of G.soja and G.max was analyzed. Two clusters corresponding to G.soja and G.max and the intermediate types including two accessions were obviously separated. The band M-CG/E-CGA-4 was specific for G.soja and the bands M-CG/E-CGA- 12 and M-CGA!E-GGC-14 characteristic for G.max. They could be treated as the characteristic bands in distinguishing G.soja from G.max. The intermediate accessions were classificd into (7.soja based on the specific characteristic bands they owned and the genetic relationship revealed by AFLP analysis. Therefore, the data demonstrated the classification of two species (G.soja and G.max) instead of three species (an addition of G.gracilis) in subgenus Scja was appropriate. The genetic relationship coincided with geographical distribution in both G.soja and G.max, and the groups based on AFLP cluster analysis coincided with the ecological regions in...
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