Little is known about the translocation of proteins and other macromolecules from a host plant to the parasitic weed Phelipanche spp. Long-distance movement of proteins between host and parasite was explored using transgenic tomato plants expressing green fluorescent protein (GFP) in their companion cells. We further used fluorescent probes of differing molecular weights to trace vascular continuity between the host plant and the parasite. Accumulation of GFP was observed in the central vascular bundle of leaves and in the root phloem of transgenic tomato plants expressing GFP under the regulation of AtSUC2 promoter. When transgenic tomato plants expressing GFP were parasitized with P. aegyptiaca, extensive GFP was translocated from the host phloem to the parasite phloem and accumulated in both Phelipanche tubercles and shoots. No movement of GFP to the parasite was observed when tobacco plants expressing GFP targeted to the ER were parasitized with P. aegyptiaca. Experiments using fluorescent probes of differing molecular weights to trace vascular continuity between the host plant and the parasite demonstrated that Phelipanche absorbs dextrans up to 70 kDa in size from the host and that this movement can be bi-directional. In the present study, we prove for the first time delivery of proteins from host to the parasitic weed P. aegyptiaca via phloem connections, providing information for developing parasite resistance strategies.
Bibliographical noteFunding Information:
Acknowledgments We gratefully acknowledge Dr. Aaron Zelcer, Department of Vegetable Research, ARO, The Volcani Center-Israel, for his contribution of transgenic tobacco seeds. This research was supported by Research Grant No. IS-3048-98 from BARD, The United States–Israel Binational Agricultural Research and Development Fund. Additional support is acknowledged to J.H.W. from the U.S. Department of Agriculture (Hatch project no. 135798).
- AtSUC2 promoter
- Orobanche aegyptiaca
- Phelipanche aegyptiaca
- Transgenic tobacco
- Transgenic tomato