SMITH, R. ALAN*, DIANE M. FERGUSON, TODD J. BARKMAN, AND CLAUDE W. DEPAMPHILIS. Department of Biology, Vanderbilt University, Nashville, TN 37235 and Department of Biology and Institute of Molecular Evolutionary Genetics, Penn State University, University Park, PA 16802, and Department of Botany and Plant Pathology, Michigan State University, East Lansing, MI 48824. - Molecular phylogenetic evidence for the origin of Lennoaceae: A case of adelphoparasitism in the angiosperms?
Lennoaceae are a small family of root parasites endemic to Mexico and
the southwestern United States. These plants are non-photosynthetic
and exhibit a reduction of morphological features which makes
systematic placement difficult. Earlier studies of Lennoaceae based
on floral and pollen morphology have suggested relationships with
Boraginaceae, "Hydrophyllaceae," or Verbenaceae. Molecular
evidence is presented from all three genomic compartments to test
these hypotheses. The plastid gene rps2, the mitochondrial genes cox1
and atpA and the nuclear ITS region were sequenced and subjected to
phylogenetic analysis. Preliminary results indicate that a
monophyletic Lennoaceae is most closely related to Ehretioideae, a
subfamily of Boraginaceae. This subfamily contains host plants of
Lennoaceae, indicating a possible case of adelphoparasitism, the
first such association suspected among the angiosperms. Further
investigation should resolve this question and determine the closest
extant relative of Lennoaceae among this group.
Key words: adelphoparasitism, Boraginaceae, Hydrophyllaceae, Lennoaceae, mitochondrial DNA, parasitic plant