Carbon / nitrogen interactions between legumes and parasitic plants

Research Project

Project/Area Number	26870087
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Multi-year Fund
Research Field	Plant nutrition/Soil science Plant protection science
Research Institution	University of Tsukuba
Principal Investigator	IRVING Louis 筑波大学, 生命環境系, 助教 (60597178)
Project Period (FY)	2014-04-01 – 2018-03-31
Project Status	Completed (Fiscal Year 2017)
Budget Amount *help	¥3,640,000 (Direct Cost: ¥2,800,000、Indirect Cost: ¥840,000) Fiscal Year 2016: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2015: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000) Fiscal Year 2014: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Keywords	hemiparasite / Phtheirospermum / carbon / N status / conditional parasitism / parasite / legume / nitrogen / photosynthesis / carbon transfer / carbon allocation / alfalfa / phtheirospermum / clover / orobanche / Plant parasitism / Photosynthetic recovery / Phloem / xylem / Host quality
Outline of Final Research Achievements	Our understanding of hemiparasitic plants is that they steal nutrients, hormones and water, but little carbon. In the last year, we have made three major discoveries about the parasite Phtheirospermum japonicum and its host, Medicago sativa. P. japonicum is a carbon-feeding hemiparasite. It does not steal nutrients from the host, but supplements its growth with host-derived photoassimilate. Parasitic intensity in the Phtheirospermum / Medicago system is mediated by host nutrient status. Where the host is supplied nitrogen, it is able to resist the parasite, and suffers no damage. The parasite receives no benefit of attachment to the host. Under nutrient-deprived conditions, host growth is decreased by 75%, and the parasite increased by 33%. Parasite will not grow without N, thus, we must separate out host and parasite nutrient supply. Previous experiments have shown increased host photosynthesis caused by parasite attachment to clover, but only under nutrient deprived conditions.