| Summary: | 碩士 === 國立嘉義大學 === 農學研究所 === 96 === This study is to use the Random Amplified Polymorphic DNA (RAPD) method to analyze the genetic diversity of germplasm in terms of quantitative characters among the 126 okra lines that AVRDC–The World Vegetable Center collected from 11 Asian countries. The horticultural characters investigated include: days to flowering; node no. of main stem at first flowering; main stem heights at first flowering and one and two months after first flowering; branch no.; capsule no. per plant; yield; lengths of young and mature capsules; and 100-seed weight. The results of cluster analysis show that there are divergences among tested materials. However, divergences among origins of materials are not obvious. First, using 11 RAPD primers, 320 DNA bands were obtained. Among them, 298 bands (93.31%) were polymorphic ranging between 350 and 2400 bp. Next, Jaccard's genetic similarity coefficients were calculated and a dendrogram was constructed by the unweighed pair-group method of arithmetic average (UPGMA). Results show that TOT2779 and TOT2781, both from the Philippines, have the highest level of similarity (0.811). On the other hand, TOT3142 and TOT1511, both also from the Philippines, have the lowest level of similarity (0.211). Most entries have similarity levels ranging from 0.55 to 0.7. The dendrogram from the cluster analysis revealed the tested entries could be divided into two major groups denoted as A and B when the genetic similarity 0.42 was used as a base line. (Because of its wild divergence from the rest of tested entries, TOT1511 from the Philippines was not included in these two groups.) Two subgroups are observed among the 48 lines in Group A, each subgroup having two smaller groups. The 78 lines in Group B could be divided into three subgroups; each subgroup also has two smaller groups. Subgroup A-1 contains the lines from countries that have less okra lines than other countries, while subgroup A-2 and group B include the lines from countries that have more lines. Hence grouping of the okra lines by countries is distinct; the lines from the same countries tend to cluster together. On the other hand, there is no correlation between the results of RAPD and horticultural characters. The latter could be due to non-stability of polymorphic bands caused by DNA purity, PCR conditions, etc. The RAPD method for stable polymorphic bands to link with horticultural traits needs to be further improved. Despite of this, the significant part of this study shows the current level of polymorphism is stable enough for the gross level of diversity study including the origin of materials.
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