Abstract
BackgroundOf the c. 450 families of flowering plants, only two are left "unplaced" in the most recent APG classification of angiosperms. One of these is the Apodanthaceae, a clade of c. 19 holoparasitic species in two or three genera occurring in North and South America, Africa, the Near East, and Australia. Because of lateral gene transfer between Apodanthaceae and their hosts it has been difficult to infer the family's true closest relatives.ResultsHere we report a phylogenetic analysis of 16 accessions representing six species of Apodanthaceae from the United States, Chile, Iran, and Australia, using the mitochondrial matR gene and the nuclear 18S gene. Data matrices include 190 matR sequences from up to 95 families in 39 orders of flowering plants and 197 18S sequences from 101 families representing the 16 orders of rosids. Analyses were performed at the nucleotide and at the amino acid level. Both gene trees agree with angiosperm phylogenies found in other studies using more genes. Apodanthaceae and the seven families of the order Cucurbitales form a clade with 100% bootstrap support from matR and 56% from 18 S. In addition, the Apodanthaceae and Cucurbitales matR gene sequences uniquely share two non-synonymous codon changes and one synonymous change, as well as a codon insertion, already found by Barkman et al. (2007).ConclusionsApodanthaceae belong in the Cucurbitales with which they share inferior ovaries, parietal placentation and a dioecious mating system, traits that are ancestral in Cucurbitales and which can now be interpreted as possible synapomorphies of an enlarged order Cucurbitales. The occurrence of Apodanthaceae in the Americas, Africa, the Near East, and Australia, and their adaptation to distantly related host species in the Fabaceae and Salicaceae suggest a long evolutionary history.
Highlights
Of the c. 450 families of flowering plants, only two are left “unplaced” in the most recent APG classification of angiosperms
The family contains three genera: the neotropical Apodanthes with about five species from Panama throughout South America to Uruguay and Argentina; the disjunctly distributed Pilostyles with c. nine species in the southern
We found the codon insertion uniquely shared by Cucurbitales and Apodanthaceae, previously reported for P. thurberi, Begonia, and Echinocystis
Summary
Of the c. 450 families of flowering plants, only two are left “unplaced” in the most recent APG classification of angiosperms. 450 families of flowering plants, only two are left “unplaced” in the most recent APG classification of angiosperms. One of these is the Apodanthaceae, a clade of c. 19 holoparasitic species in two or three genera occurring in North and South America, Africa, the Near East, and Australia. 450 families of angiosperms [1] are about 11 parasitic lineages [2] of which some have completely lost the ability to photosynthesize. Such non-photosynthetic parasites grow embedded within the host tissues (as endoparasites) and emerge only during sexual reproduction [3]. The family contains three genera: the neotropical Apodanthes with about five species from Panama throughout South America to Uruguay and Argentina; the disjunctly distributed Pilostyles with c. nine species in the southern
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
