Genetic Characterization of Pili (Canarium ovatum Engl.) from Albay, Camarines Norte, and Camarines Sur Through Isozyme Analysis
Merlyn S. Mendioro*, Ma. Geneleen Q. Diaz, Vera Marjorie E. Velasco,
Maylynn C. Alcaraz, Roselle C. Lalamunan, Karen G. Amoloza and Luisa N. Villamael
Institute of Biological Sciences, College of Arts and Sciences
University of the Philippines Los Baños, College, Laguna, Philippines
Based on esterase (EST), acid phosphatase (ACP), and alkaline phosphatase (ALP), genetic variability was noted in 19 accessions of pili (Canarium ovatum Engl.) from Albay, Camarines Norte, and Camarines Sur and in the 11 accessions of unknown origin. Seven presumptive loci were determined. Two presumptive loci were observed in EST (EST1 and EST2), ACP (ACP1, and ACP2) while three for ALP (ALP1, ALP2, and ALP3). Percent polymorphism was 100%. Using a similarity coefficient of 0.60, the 30 accessions were divided into 5 clusters. Accessions of different origin grouped together which would indicate that variability exists in the accessions considered. To further prove that genetic diversity exists in pili, 25 accessions collected from Oas, Albay were also subjected to isozyme analysis. Eighteen presumptive loci were determined: 3 for glucose-6-phosphatase dehydrogenase (G6PD), 2 each for EST, phosphogluconate dehydrogenase (PGD), malate dehydrogenase (MDH), ACP, ALP, and phosphoglucomutase (PGM), and 1 each for glutamate oxaloacetate (GOT), phosphoglucoisomerase (PGI), and alcohol dehydrogenase (ADH). Only ALP2, G6PD2, and G6PD3 were monomorphic. The observed heterozygosity for ACP1, ACP2, ALP1, EST1, EST2, and PGD2 was higher compared to the expected heterozygosity. Fifteen of the presumptive loci were polymorphic (83.33%). Considering a similarity coefficient of 0.70; 4 clusters were obtained although the 25 accessions were collected only from Oas, Albay. This would indicate that accessions were genetically different. Pili being dioecious is an obligate cross-pollinating crop. Genetic variability observed can be explained through recombination occurring during sexual reproduction.
The Philippines, a tropical country, is very rich in edible fruit and nut bearing trees, of which about 167 are indigenous (Villegas & Coronel 1979). Several fruit trees that bear edible nuts are claimed to have their center of diversity in the Philippines. The most important of these is pili, Canarium ovatum (Figure 1), of which geographic distribution in the country remains limited to areas located relatively closer to its center of origin (Coronel 1996). Pili is considered to be the most important nut-producing species indigenous to the country. It has a nationwide acceptance and has great potential to develop into a major industry (Philippine Fruit Network 2001). As a nut, the development of this crop is promising as demand for processed kernel is rising. The pili nut kernel (Figure 2) is the most important part of the tree and has many uses (Coronel 1996). Pili nuts are mainly used to manufacture candies and confectioneries, while pili nut oil is highly in demand local and in foreign countries like Guam, Australia, Canada, and United States (PCARRD 1997).
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