Isozyme Characterization and Diversity Among the Philippine Populations of Oryza officinalis Wall ex. Watt conserved ex situ
Thirty-nine ex situ accessions of Philippine Oryza officinalis Wall ex Watt were characterized for isozyme electrophoretic profile and analyzed for diversity. Polymorphism was detected in phosphoglucoisomerase, arginine aminopeptidase, alanine aminopeptidase, esterase-9, and leucine aminopeptidase. Zymograms revealed the electrophoretic profiles of the populations across enzymes. Polymorphism was shown in the number of resulting bands, positions of bands, and in the general banding pattern. Zymogram patterns showed that the experimental populations can be grouped into two sets: seed collections and vegetative collections. Vegetative collections showed more variations relative to banding characteristics, hence, indicating comparative diversity. Seed collections exhibited very low variation in isozyme features. Cluster analyses confirmed separation of the two sets. Vegetative collections also showed some degree of geographic association. Reduced isozyme polymorphism indicated loss of allelic variation among the seed collections and could be ascribed to factors relating to collecting sample size, and procedural practices in handling germplasm for ex situ regeneration and conservation. On the other hand, technical instability of the isozyme system may have similarly contributed to the present results obtained. Further molecular investigation including studies on factors that influence genetic structure of populations underex situ conservation are recommended to verify the results obtained.
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