Identification of genes necessary for parasitic plant to invade host plants

Ocotber 29, 2020

Hope for development of methods to control serious pathogenic parasitic plants

A joint research group of Nara Institute of Science and Technology, RIKEN CSRS, and National Institute for Basic Biology has revealed the mechanism how parasitic plants recognize other plants that can be their hosts and invade the host bodies. Parasitic plants sense ethylene, a plant hormone that regulates the physiological actions (a signaling agent), generated by the host to start the invasion. The main genes involved in the mechanism were identified for the first time.

As parasitic plants grow on other plants (host plants) by depriving them of nutrients, they give damage on host plants. Among them, those in the Orobanchaceae family, including Striga spp. and Orobanche spp., make especially serious damage on agriculture throughout the world and recognized as agricultural pest weeds. Parasitic plants in this family make parasitic organs called "haustorium" in their own roots, attach the haustorium to the roots of the host, and invade the tissues of the hosts. Then, they connect vascular bundles to absorb nutrients. Although this process has been known, the mechanism of the haustorium to recognize the location of the host's roots and invade the tissues was unknown.

Using Phtheirospermum japonicum, a parasitic plant and native plant in Japan, the team isolated mutants showing defects in host invasion due to prolonged elongation of haustorium. In addition, the team conducted genome (genetic information) analysis and found that this phenomenon (phenotype) is caused based on abnormalities of genes involved in ethylene signaling. That is, abnormalities in the ethylene signaling of parasitic plants prevent them from recognizing the presence of host plants, and thus from invasion. In addition, the rate of invasion decreased when parasitic plants were infected with host plants with ethylene synthesis defect, indicating that parasitic plants recognize ethylene generated by the host plants for their invasion. This is the first to identify the genes necessary for host invasion, and the findings are expected to be useful for the development of methods to control serious pathogenic parasitic plants.

Original article
Science Advances doi:10.1126/sciadv.abc2385
S. Cui, T. Kubota, T. Nishiyama, Juliane K. Ishida, S. Shigenobu, T. F. Shibata, A. Toyoda, M. Hasebe, K. Shirasu, S. Yoshida,
"Ethylene signaling mediates host invasion by parasitic plants".
Ken Shirasu
Group Director
Plant Immunity Research Group