How parasitic plants approach hosts elucidated

August 18, 2022

The development of ways to prevent agricultural damage caused by harmful parasitic weeds is expected

An international collaborative research group, including the RIKEN CSRS and the Nara Institute of Science and Technology, clarified how parasitic plants grow their roots toward host plants.

Root parasitic plants go through three steps to complete invasion: 1. germinating upon locating a nearby host plant, 2. extending their roots toward the host roots, and 3. connecting them to the host roots to deprive the host of nutrients and water. While the steps 1 and 3 have been well-studied, little has been investigated on the underlying mechanism of the step 2, known as tropism.

In this study, the research group found that the roots of Phtheirospermum japonicum, a parasitic member of the Orobanchaceae, show tropism to strigolactones (SLs), rhizospheral signaling compounds, released from host roots. This tropism could be a strategy unique to parasitic members of Orobanchaceae as this property is found in Striga hermonthica, the same member of the Orobanchaceae causing agricultural damage in Africa, but not in non-parasites. In addition, they showed that tropism to SLs involves the transportation of auxin, a plant hormone, and is attenuated in ammonium ion-rich conditions. They further identified a receptor that recognizes SLs and induces tropism.

The findings of this research will contribute to developing ways to eliminate damage by root parasitic plants, which parasitize major crops to cause severe reductions in their yields around the world.

Original article
Nature Communications doi:10.1038/s41467-022-32314-z
S. Ogawa, S. Cui, A. R.F. White, D. C. Nelson, S. Yoshida, K. Shirasu,
"Strigolactones are chemoattractants for host tropism in Orobanchaceae parasitic plants".
Satoshi Ogawa; Visiting Researcher
Ken Shirasu; Group Director
Plant Immunity Research Group