Identifying host plants of Hyobanche L. (Orobanchaceae) by DNA sequencing of host root tissue

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.

Fynbos

Coastal habitats

Karoo

High Veld

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