Development of SSR markers from Musa balbisiana for genetic diversity analysis among Thai bananas

摘要

Bananas in Thailand have been surveyed by our team to be at least 140 cultivars in the plantations, 10 wild species and, 4 introduced species. To characterize the genetic relationship of species and cultivars, a set of novel SSR markers was developed. Totaling 53 clones containing SSR motifs were isolated from SSR-enriched library of wild Musa balbisiana Colla 'Tani' (BB). Selected positive clones were used to design 28 primer pairs for amplification of 12 wild and 82 cultivar accessions with genome designations AA, AB, AAA, AAB, ABB, and BBB. These SSR markers loci were homology searched to the banana genomes to map their locations. The seven-sets multiplex PCR approach using four fluorescent-labeled universal primers were utilized for cost effectiveness. Capillary fragment analysis yielded the accurate size of amplicons for evaluation of particular patterns for each cultivar. Phylogram and Structure analysis presented the specific genotype of genome groups (A and B genotypes, polyploid hybrid genomes) and cultivar groups. By A:B specific alleles ratio, accurate genome designations of hybrids can be determined. Additionally, a marker, characterized to be partial plastid ycf2 gene, indicated the maternal identification of hybrid cultivars. One SSR marker was also preliminary tested with some wild species and advised to be the candidate fingerprinting marker for species identification. In conclusion, SSR marker sets developed here proved their exploitation in detailed identity and relationship of cultivated bananas, which would be useful for genetic conservation and ongoing breeding programs in Thailand and other areas.