A genetic assessment of Musa viridis and Musa splendida indicates that they are conspecific

Abstract

Species delimitation based on morphological trait characteristics can be challenging due to overlapping trait variation. This is especially true for closely related sympatric species with individuals exhibiting intermediate phenotypes. However, traditional morphological and molecular analyses often lack resolution to determine whether two taxa are distinct species or are conspecific. Recent advances in generating and processing high-throughput sequencing data enable the use of high-resolution data to address such taxonomic problems. Within the banana family (Musaceae), several species have an ambiguous taxonomic status. Musa viridis and M. splendida are two wild Vietnamese banana species that are locally used as ornamentals or added to rice wine as flavor enhancers. Their fruits are not favored for consumption, mainly because they have seeded bananas. Both species have very similar morphological trait characteristics. The main difference between these species is the colour of the male flower bud: M. splendida has red flower buds, whereas M. viridis has pink flower buds. Both species also occur sympatrically with some populations comprising individuals with red and pink male flower bracts. In this study, we applied a high-throughput (DArT) sequencing approach to investigate the taxonomic status of M. viridis and M. splendida based on 121 plants from nine different populations. Maximum likelihood phylogenetic trees were reconstructed for over 12,000 loci (< 120 base pairs) and one ASTRAL consensus tree was generated from all locus trees. The ASTRAL phylogenetic tree showed that individuals did not cluster by species but by population, with individuals from different species appearing in the same clade. Consequently, we propose to treat M. viridis as a synonym of M. splendida. Our work clarified the taxonomic status of two wild relatives of cultivated bananas, potentially facilitating their use in crop breeding programs in the future.