Transformation and regeneration of the holoparasitic plant Phelipanche aegyptiaca

Here we demonstrate that transformation of Phelipanche aegyptiaca is achieved by infection of 3 month-old in vitro grown P. aegyptiaca calli with Agrobacterium rhizogenes harboring the yellow fluorescent protein (YFP). Four months later, YFP-positive regenerated calli were inoculated onto tomato plants growing in a minirhizotron system. Eight days after inoculation, transgenic parasite tissue formed lateral haustoria that penetrated the host and could be visualized under UV illumination through intact host root tissue. YFP-positive shoot buds were observed one month after inoculation.This work constitutes a breakthrough in holoparasitic plant research methods. The method described here is a robust system for transformation and regeneration of a holoparasitic plant and will facilitate research on unique parasitic plant capabilities such as host plant recognition, haustorial formation, penetration and vascular connection.Parasitic weeds belonging to the genera Orobanche and Phelipanche have lost through evolution their autotrophic way of life, switching from photosynthesis to obtaining their resources by parasitizing other plants. Parasites capture host water and nutrients through a specialized organ, the haustorium, which invades the host root and connects with the host vascular system [1-3]. Phelipanche aegyptiaca (syn. Orobanche aegyptiaca) is an important parasitic weed attacking many crops in Asia and the Middle East. Conventional control based on cultural methods, herbicides, or host breeding for parasitic plant resistance, have not attained complete success due to several factors associated with the parasite life cycle, including high fecundity (hundreds of thousands of seeds per parasite), seed longevity in the soil, the subterranean location of the young parasite that effectively hides it from the farmer, the tightly coordinated parasitic and host life cycles, and the scarcity of sources of resistance in most affected crop species [4-6]. Biotechnological cont