Genetic diversity analysis and fingerprinting of Philippine Musa balbisiana genotypes

Inglés. The Philippines boasts of a rich diversity of bananas (Musa). This project analyzed the genetic diversity of Musa balbisiana in the country using short sequence repeats or SSRs (or microsatellite) primers and established DNA fingerprints for the most economically important Saba cultivars. Moreover, the database of horticultural data for the collection of additional germplasm of M. balbisiana was continued and molecular data added for the additional and existing germplasm. A total of 51 primer pairs (45 from Musa and 6 from other crops) obtained from literatures were screened for PCR amplification and polymorphism across the 13 Saba cultivars. The genetic diversity among 81 Philippine Saba (Musa balbisiana) gene bank collections and four M. acuminata accessions were analyzed using microsatellite markers. Eleven primer pairs were found to be polymorphic across all genotypes and amplified a total of 34 alleles. The discriminatory power of the primers were relatively high with mean polymorphism information content (PIC) value of 0.548. Genetic diversity was measured in terms of Heterozygosity, Fixation index, and Genetic distance. Observed heterozygosities (H sub O) were found to be significantly greater than the expected (H sub O). Fixation indices (mean F = -0.7178) were negative which suggests an excess of heterozygotes and shows that diversity has been maintained within the gene bank collection. Greatest genetic distance (0.7162) was observed between Lakatan (AA) and Giant Cardaba (BBB). Cluster analysis revealed Tiparot (ABBB) as the most distant saba cultivar indicating the ability of markers to distinguish genetic elements of the A from B genome. To generate DNA fingerprints for the 13 Philippine Saba cultivars, 14 polymorphic primers were utilized. A total of 47 alleles were generated, with a mean of 3.36 alleles per locus, ranging from one to eight alleles. The resolving power of molecular markers measured as the Polymorphism Information Content (PIC) ranged from 0.23 to 0.80. The dendrogram using UPGMA-SAHN cluster analysis based on microsatellite polymorphism showed that the Saba cultivars clustered into 2 groups at the 55% similarity level. Cluster analysis separated the cultivars of Musa balbisiana Colla from genotypes of Musa acuminate Colla. The 14 polymorphic SSR primers were shown to be able to identify and differentiate the 13 Saba cultivars. The results of this study provide useful information for proper identification of Saba cultivars suitable for specific needs of the industry. A total of 226 accessions of cultivated or edible (mostly Saba) (116) and wild Musa balbisiana (110) are in the existing Musa germplasm collection of the National Plant Genetic Resources Laboratory.

Inglés. The wild M. balbisiana accessions were mostly collected from 1997 to 1999 and identified as the world's largest germplasm collection of its kind. They are currently being maintained at the Field Genebank of NPGRL in Pasong Kipot, UPLB. On the other hand, the edible bananas accessions (mostly Saba) have been collected through the project' development of dwarf banana cultivars (Saba and Cardaba) through irradiation funded by Department of Science and Technology - Philippine Council for Agriculture, Aquatic and Natural Resources, Research, and Development (DOST-PCAARRD). For this project a total of 48 accessions of both edible and wild species were collected in the different banana growing areas throughout the country. These include the provinces of Benguet (7), Mt. Province (4), Catanduanes (7), Albay (1), Sorsogon (2), Camarines Norte (4), Camarines Sur (2), Northern Samar (6), Romblon (4), Surigao del Norte (3), Leyte (1), Biliran (3), Zambales (3), Pampanga (1), Maguindanao (1), South Catabato (1), and Misamis Occidental (1). Some of edible species collected are Dippig, Dadanugin, Pakawan, Dapuan, Daydayawen, Ginuyod, Calibo, Calibong, Puti, Tinumbaga, Pilipita, and Tu-Ol. The wild species includes Pacol, Alinsanay, Agutay, Moko, wild abaca, among others. Passport data of the different M. balbisiana accessions were taken during the collection trips. The data include PHL number (accession number), old accession number GB number (NPGRL registration number), cultivar/variety name, donor, donor ID number (if any), province of collection, town of collection, village of collection, sitio of collection, date of collection, coordinates of collection site (latitude/longitude) and altitude. A total of 117 edible and wild M. balbisiana have been characterized. The data are maintained as flat file (MS Excel) and as word (MS Word). The other accessions will be characterized when they reach maturity and flowering stages. There are 113 characters on record from various banana parts.