First Application of FLORICAULA second intron (FLint2) as a Phylogenetic Marker in Bananas (Musaceae)

The utility of potential low-copy genes as molecular markers is becoming more practical for phylogenetic study because they often outperform the multi-copy genes. The application of a low-copy gene, FLORICAULA second intron (FLint2), that contributes to early flowering as a phylogenetic marker in bananas (Musaceae), has never been reported. Yet, inflorescence remains a dominant distinguishing characteristic in bananas and its closely related species. Hence, this study aimed to determine the potential phylogenetic utility of FLint2 compared with Internal Transcribed Spacer (ITS) as a multicopy gene in bananas and closely related species. Results showed that FLint2 was easily amplified under optimized PCR conditions. The FLint2 amplicons were found to be medium length (450-500 bp) in bananas and significantly differ from its closely related species of Heliconiaceae and Strelitziaceae (1200-1300 bp). The sequences were GC-rich and highly variable at 89.11%. Individual maximum-likelihood phylogenetic trees of both markers were mostly congruent. The FLint2 provides an alternative internal topology within bananas and is better at separating the cultivar genome groups, although weak in bootstrap support. The combined sequences improved the tree topology and strong-supported clades. In conclusion, FLint2 was proven to have high potential phylogenetic utility to intraspecific and genomic levels in bananas and it is also suggested to be suitable for use in closely related species within the Zingiberales order.