MICROSATELLITE MARKERS FOR CLASSIFYING AND ANALYSING GENETIC RELATIONSHIP BETWEEN BANANA CULTIVARS IN INDONESIA

Abstract

In this study, microsatellite markers were used to identify Musa genomic groups and to investigate genetic relationships among banana accessions from various areas in Indonesia. One hundred sixteen banana accessions were analysed using MaCIR108 and Ma-3-90 primer pairs for identifying genomic groups. Six additional SSR primer pairs were used for genetic relationship analysis. The results showed that 73 accessions should be classified in the AA/AAA and AAA genomic groups, two accessions in the BB genomic group, 21 accessions in the AAB genomic group and 20 accessions in the ABB genomic group. Ninety-nine out of the 116 accessions were unique genotypes while the rest were synonyms. The dendrogram generated by UPGMA analysis separated the 116 banana accessions into two main clusters with a similarity of 0.13. All banana accessions belonging to the BB, ABB and AAB genomic groups clustered in the first main cluster, together with the majority of the accessions containing the pure A genome. The second main cluster was formed of 11 accessions of AA/AAA and AAA genome. Within the first main cluster, the accessions containing the B genome were clustered according to their genomic group, except four AAB accessions clustering with accessions containing the A genome alone. The ABB genomic group appeared closer to the BB than to the AAB genomic group. The AA and AAA banana accessions could not be significantly distinguished, although the majority of accessions tended to be clustered according to their ploidy level. INTRODUCTION Most edible bananas originated from two wild species, Musa acuminata Colla (2n) and Musa balbisiana Colla (2n). Scientifically, banana cultivars are often referred to by their genomic groups, which are categorised on the basis of their ploidy levels and the genomes they contain. Ploidy in bananas includes diploids, triploids and rare tetraploids, resulting in genomic groups: AA, BB, AAA, AAB, ABB, AAAB ... with the letters A and B representing the contribution of M. acuminata and M. balbisiana, respectively. The hybrid bananas that evolved from the two natural species mostly formed triploid cultivars (Heslop-Harison and Schwarzacher, 2007). Genomic constitution plays an important role in the classification of bananas (Pillay et al., 2004). Cultivar identification based on morphological characters is not always easy due to the influence of environmental factors. Molecular approaches have been recognised to be more effective than morphological techniques to distinguish banana cultivars and classify them in genomic groups (Ford-Lloyd et al., 1997). Microsatellites are one of the most informative molecular markers to reveal genetic diversity of banana cultivars (Creste et al., 2003, 2004). Such markers have been used for genotype identification of many plant species (Perera et al., 2001; Chakravarthi and Naravaneni, 2006). Microsatellites are DNA regions that consist of short repeat units flanked by conserved sequences that are unique to specific loci in the genome (Semagn et al., 2006). In previous studies in banana, several microsatellite primers were shown to be useful in producing diagnostic characters for different genomic groups (Kaemmer et al., 1997; Creste et al., 2005), with a determination key based on application of these markers Proc. Int’l ISHS-ProMusa Symp. on Global Perspectives