Evolution and Classification of Musaceae Based on Male Floral Morphology

Abstract

Classification of the banana family (Musaceae) into three genera, Musa, Ensete and Musella, and infrageneric ranking are still ambiguous. Within the genus Musa, five formerly separated sections were recently merged into sections Musa and Callimusa based on seed morphology, molecular data and chromosome numbers. Nevertheless, other key morphological characters of the genera, sections, and species have not been clearly defined. This research aims to investigate male floral morphology, classify members of the banana family based on overall similarity of morphological traits using 59 banana accessions of 21 taxa and make inferences of the evolutionary relationships of 57 taxa based on ITS, trnL-F, rps16 and atpB-rbcL sequences from 67 Genbank and 10 newly collected banana accessions. Fifteen quantitative characters were examined using principal component analysis and canonical discriminant analysis and 22 qualitative characters were analyzed by the Unweighted Pair Group Method with an Arithmetic Mean (UPGMA). The results showed that fused tepal morphology, median inner tepal shape and length of style supported the three clades of Musa, Ensete and Musella, while shapes of median inner tepal and stigma classified the two Musa sections. In conclusion, a combination of morphological characters of male flowers and molecular phylogenetics well support the taxonomic arrangement within the banana family and the Musa genus and assist in selection of characters to construct an identification key of Musaceae.