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Identifying host plants of Hyobanche L. (Orobanchaceae) by DNA sequencing of host root tissue Andrea D. Wolfe and Nidia Arguedas The Ohio State University. Background on Hyobanche. Small genus of holoparasitic plants endemic to southern Africa Eight species described as of 1996
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Identifying host plants of Hyobanche L. (Orobanchaceae) by DNA sequencing of host root tissue Andrea D. Wolfe and Nidia Arguedas The Ohio State University
Background on Hyobanche • Small genus of holoparasitic plants endemic to southern Africa • Eight species described as of 1996 • One not seen in herbarium collections; three to be submerged into one spp • Another seven to be described • Host plants noted on herbarium sheets • Asteraceae, Ericaceae, Euphorbiaceae, Poaceae, Restionaceae, Sterculiaceae, Thymelaeaceae
sp. nov. sp. interm. sanguinea atropurpurea.
Background on Hyobanche • Small genus of holoparasitic plants endemic to southern Africa • Eight species described as of 1996 • One not seen in herbarium collections; three to be submerged into one spp • Another seven to be described • Host plants noted on herbarium sheets • Asteraceae, Ericaceae, Euphorbiaceae, Poaceae, Restionaceae, Sterculiaceae, Thymelaeaceae
Usually based on proximity. . . which may or may not have anything to do with the actual host plant!
Rhizomes of Hyobanche may be several meters long, and host roots are attached along the length of the rhizome on specialized haustoria from leaf bracts.
Haustorial connections are generally fragile, which makes tracing the host-parasite attachment difficult.
Methods • Excavate rhizome system of Hyobanche • Collect roots attached via haustorial connections • Collect leaf tissue of plants in vicinity • Sequence ITS and rbcL from roots and leaves • Matching sequence infers host of Hyobanche
Conclusions • DNA “fingerprinting” approach works well for identifying hosts of Hyobanche • Positive identifications made for every population sampled • Host range of coastal populations primarily in Asteraceae • Also found on Passerina and Bromus
Acknowledgments Field Assistance: Brad Ripley, Tony Dold, Beyers Cronje Funding: National Science Foundation