Parasitic plants employ plant hormones to "fatten" their hosts

May 2, 2017

Cytokinin transport between plants is the key

An international joint research group from RIKEN CSRS, the Sainsbury Laboratory, the Tokyo University of Science, the Nara Institute of Science and Technology and others has discovered that parasitic plants use cytokinin to manipulate the growth of their host plant to become more efficient parasites.

The group focused on hypertrophy of abnormal secondary growth in parasitized host plant tissues. Cytokinin is known to promote secondary growth. When visualizing cytokinin response using a fluorescent protein reporter, researchers observed an almost simultaneous cytokinin response in both the host and parasite upon initial parasite establishment. Further investigation revealed that parasite-synthesized cytokinin is transported to the host plant, inducing a cytokinin response throughthe host plant's cytokinin receptors that results in abnormal secondary growth. Researchers also found that hypertrophy of host vascular tissue contributes to efficient parasitism. By thickening the vascular bundles of the host plant, which is a nutrient transport route, the parasite plant seems to be able efficiently capture nutrients for itself.

This is the first study to clarify the role of substances transported from parasite to host plant and should serve as an important foundation for exploring biologically active substance transport in this context.

Original article
Proceedings of the National Academy of Sciences doi:10.1073/pnas.1619078114
T. Spallek, C. W. Melnyk, T. Wakatake, J. Zhang, Y. Sakamoto, T. Kiba, S. Yoshida, S. Matsunaga, H. Sakakibara, K. Shirasu,
"Inter-species hormonal control of host root morphology by parasitic plants".
Thomas Spallek; Foreign Postdoctoral Researcher
Takanori Wakatake; Postdoctoral Researcher
Ken Shirasu; Group Director
Plant Immunity Research Group