Genetic and morphological characterization of red mulberry (Morus rubra L.), white mulberry (Morus alba L.) and their hybrids

Qualitative morphological observations suggest that hybridization between two species of mulberry, the North American red mulberry (Morus rubra ) and Asian white mulberry (Morus alba), has occurred. To confirm this phenomenon, both morphological and genetic variation between the two species were examined to identify distinguishable traits. Morphological analysis using cluster analyses, principal components analyses, and discriminant analyses all revealed that leaf size and lower leaf surface hairiness were ideal characteristics for discerning between the red and white mulberry samples. The maternal lineages of the specimens were then traced using the polymorphisms in the trnL/trnF region of the chloroplast DNA. This region revealed a restriction enzyme site (RFLP) that is unique to red mulberry samples. The RFLP was used as a marker to distinguish between the two species. The morphological and RFLP data were compared for consistency of species identification. Any inconsistencies between the two analyses suggest hybrid individuals.