AUTHOR=Fu Weirui , Liu Xiaoqing , Zhang Naixin , Song Zhiping , Zhang Wenju , Yang Ji , Wang Yuguo 

TITLE=Testing the Hypothesis of Multiple Origins of Holoparasitism in Orobanchaceae: Phylogenetic Evidence from the Last Two Unplaced Holoparasitic Genera, Gleadovia and Phacellanthus

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01380

DOI=10.3389/fpls.2017.01380

ISSN=1664-462X

ABSTRACT=<p>Orobanchaceae is the largest family among the parasitic angiosperms. It comprises non-parasites, hemi- and holoparasites, making this family an ideal test case for studying the evolution of parasitism. Previous phylogenetic analyses showed that holoparasitism had arisen at least three times from the hemiparasitic taxa in Orobanchaceae. Until now, however, not all known genera of Orobanchaceae were investigated in detail. Among them, the unknown phylogenetic positions of the holoparasites <italic>Gleadovia</italic> and <italic>Phacellanthus</italic> are the key to testing how many times holoparasitism evolved. Here, we provide clear evidence for the first time that they are members of the tribe Orobancheae, using sequence data from multiple loci (nuclear genes ITS, <italic>PHYA, PHYB</italic>, and plastid genes <italic>rps2, mat</italic>K). <italic>Gleadovia</italic> is an independent lineage whereas <italic>Phacellanthus</italic> should be merged into genus <italic>Orobanche</italic> section <italic>Orobanche</italic>. Our results unambiguously support the hypothesis that there are only three origins of holoparasitism in Orobanchaceae. Divergence dating reveals for the first time that the three origins of holoparasitism were not synchronous. Our findings suggest that holoparasitism can persist in specific clades for a long time and holoparasitism may evolve independently as an adaptation to certain hosts.</p>