ZEREGA, NYREE CONARD* and TIMOTHY J. MOTLEY. The Lewis B. & Dorothy Cullman Program for Molecular Systematics Studies, The New York Botanical Garden, Bronx, NY 10458 USA. - Artocarpus (Moraceae) molecular phylogeny and the systematics and origins of breadfruit, Artocarpus altilis.
Artocarpus (Moraceae) is a paleotropical genus comprised of
approximately 50 species native to the lowlands of Southeast Asia and
Oceania. The species are primarily large monoecious, latex producing
trees with a syncarpous fruit that may attain very large sizes in some
of the species (i.e. A. heterophyllus, jackfruit and A.
altilis, breadfruit). In the most recent revision of the genus
Jarrett (1959) divided Artocarpus into two subgenera based on
leaf arrangement and stipule attachment and further subdivisions were
based on fruit and laminar characters. However, molecular and
phylogenetic studies are still lacking for the genus. Additionally,
Jarrett was unable to resolve the historically confused systematics of
breadfruit, an important starch crop in Oceania. Three very closely
related Artocarpus species must be considered in this matter.
Artocarpus altilis is the cultivated primarily seedless
breadfruit, A. camansi is a wild species native to New Guinea
and possibly the Philippines and the Moluccas as well, and A.
mariannensis is endemic to Micronesia. The great morphological
variability and overlap of characters that exist within and among
these taxa has made species delineation and breadfruit origins unclear
leading Jarrett to lump all three taxa into one species called A.
communis. Sequence data from both ITS (internal transcribed
spacers) and the trnL-F region (intron plus spacer) for 25
ingroup and six outgroup taxa were analyzed using parsimony analysis.
The results suggest that Artocarpus is monophyletic, but do not
entirely support Jarrett's circumscription of the genus. As the
sequence variation was not great enough to resolve issues concerning
breadfruit systematics and origins, AFLP (amplified fragment length
polymorphisms) analysis was employed at this level. The AFLP data set
suggests that Artocarpus camansi and A. mariannensis are
distinct species, which are both implicated in the origin of the
cultivated A. altilis.
Key words: AFLP, Artocarpus, breadfruit, Moraceae, Pacific