Abstract
The floral scents of Magnolia coco (distributed in Asia) and M. mexicana (New World), plus two Mexican Magnolia taxa, M. schiedeana and M. dealbata, were analyzed using GC-MS. A molecular phylogenetic analysis was also conducted using a combined data set of plastid DNA sequences obtained from GenBank to construct a well-resolved phylogenetic tree. The analysis indicated a sister relationship between subtropical-tropical Asian and American disjunct groups (including M. coco and M. mexicana) which was not shown in previous studies. Entire flowers and floral parts (sepals, petals, and gynoecia) of M. coco emitted methyl 2-methylbutanoate (83-96%), whereas entire flowers of M mexicana emitted α-farnesene (67%) which was mainly emitted from the sepals. The petals and gynoecium of M. mexicana emitted methyl 2-methylbutanoate as the main component with relatively small amount of α-farnesene. The common presence of methyl 2-methylbutanoate in the petals and gynoecium of both taxa may represent an ancestral scent profile because subtropical-tropical disjunct groups, which include M. coco in one and M. mexicana in the other, phylogenetically show a sister relationship. The floral scent of M. schiedeana was exclusively composed of monoterpenes, especially geranyl methyl ether (87%). The floral scent of M. dealbata was predominantly composed of benzenoids, especially 2-phenylethanol (78%) and methyl phenylacetate (13%).
