Molecular Systematics of The Genus Goniothalamus Hook. f. & Thomson

Abstract

The genus Goniothalamus Hook. f. & Thomson is one of the largest and most important genera in the Annonaceae. Its members are widespread mainly in South Asia and South East Asia. Many Goniothalamus species hold potential as important medicinal resources in Thai traditional medicinal practices, including, for example, the roots of G. macrophyllus (Blume) Hook. f. & Thomson. Little is known of the evolution and biogeographical history of this genus. Many morphological characters are ambiguous and reveal little phylogenetically useful information. Molecular systematics, nonetheless, provides tools that can answer these questions. Preliminary results show that the sizes of rpl16 intron, trnL intron and ITS in all species studied are about the same (i.e., 1,200, 580 and 750 bp, respectively). ITS, however, has the most phylogenetically informative sites, although the size of ITS is shorter than rpl16 intron. Of all three loci, ITS locus yields the highest number of phylogenetically informative sites, whilst cp markers give few sites. Moreover, DNA fragments from ITS have greater nucleotide substitution than the others.