DNA fingerprinting of Philippine bananas and assessment of genetic fidelity of micropropagated 'Lakatan' using simple sequence repeat markers

Simple Sequence Repeats (SSRs) were used to determine the genetic variability and relationships among 61 Philippine bananas. Ten out of 12 primer pairs tested on 61 banana accessions were found to be polymorphic and generated 43 alleles ranging from 3 to 13 alleles per primer. Seven out of the ten primers gave unique bands for some of the cultivars tested which could be useful in cultivar identification and fingerprinting. The resolving power of molecular markers measured as Polymorphism Information Content or PIC were found to be informative, which ranged from 0.68 to 0.94. Cluster analysis at the 83.1% similarity divided the dendrogram into 11 clusters with several outliers indicating a wide genetic variation existing within the different 'Musa' collections in spite of the detected identical genotypes from the collection. Clustering somehow separates the genotypes containing the M. acuminata genome alone from the rest of the genotypes with A and B genomes although no cohesive clustering among different genomic groups (i.e. diploids, triploids, and tetraploids) was observed. SSR markers and morphological characterization were also used to assess the genetic fidelity or occurrence of somaclonal variation on 29 selected micropropagated 'Lakatan Davao' and 'Lakatan Lilak'. Morphological characterization revealed only subtle differences in qualitative traits and no distinct traits was observed in any of the somaclones. However, the dendrogram on quantitative traits revealed high variability among the somaclones. All the seven primers tested revealed monomorphic bands on all loci indicating that the genetic fidelity of the somaclones was intact and that no somaclonal variation had occurred even after they passed through a series of 9 subculture cycles. However, such assumption can only be applied to the seven primers used in the study.