Molecular Based Classification and Phylogenetic Analysis of Indonesian Banana Cultivars

Abstract

Banana cultivars are complex hybrids and have been further modified by various mutations. The specific ancestor of the cultivars was difficult to be elucidated. Therefore, the taxonomic status and nomenclature have long been a complicated issue. The goals of the study were to characterize banana accessions from various regions in Indonesia based on microsatellite markers to obtain classification which is stable and accurate and to elucidate phylogenetic relationships of banana cultivars inferred from trnL-F intergenic spacer of cpDNA. The study was conducted using 151 accessions that have been morphologically classified and unclassified 116 accessions. Thirty nine accessions which represented various genomic groups and 12 sequences of different taxa of Musa downloaded from GenBank were used for phylogenetic analysis. Banana accessions were characterized using 12 microsatellite primers. Only 8 primers: MaCIR108; MaCIR332a; MaCIR327b; Ma-1-17; Ma-1-27; Ma-1-132; Ma-3-90; and Ma-3-139 produced clear alleles and exhibited polymorphic banding patterns. Total 267 banana accessions were effectively classified into 3 species based only on: 4 alleles of MaCIR108 with the size of more than 270 bp; alleles of MaCIR108 with the size of 270 bp or less; and 1 allele of Ma-3-90 with the size of 152 bp. There are 130 accessions of AA or AAA; and AAA designated under Musa acuminata, 10 accessions of BB designated under M. balbisiana, 64 accessions of AAB and 63 accessions of ABB designated under hybrid species M. x paradisiaca. Eleven accessions of pure the A genome and 9 accessions containing the B genome previously identified based on morphology have been reclassified into M. x paradisiaca and M. acuminata. The study also exhibited that microsatellites are an effective marker for identifying banana cultivars. Analysis of 267 banana accessions using the 8 primers detected only 208 genotypes because 88 accessions formed 29 identical genotypes. In general, the banana accessions clustered according to their genomic groups, except 15 accessions of AAB; accessions of AA or AAA; and AAA. In the phylogeny inferred from the trnL-F region, 40 accessions having the A-type chloroplast consisting of AA wild; AA; AA or AAA; AAA; AAB; and ABB cultivars were clearly differentiated from 11 accessions having the B-type chloroplast consisting of BB, AAB, and ABB cultivars. The A-type chloroplast accessions are most probably derived from female M. acuminata, while those with the B-type chloroplast may be derived from female M. balbisiana. However, the specific acuminata ancestor of each cultivar remains unidentified. Genetic relationships among banana accessions based on the trnL-F region are not in agreement with those based on the microsatellite most probably due to the differences of inheritance mode of both DNA markers.