Arbuscular mycorrhiza (AM) formation is a widespread symbiotic interaction between 80-90% of land plants and soil fungi. The plant benefits from enhanced inorganic nutrient supply mediated by the fungal hyphae network in the soil. In return, from the plant, the fungi draw organic nutrients which are thought to be supplied primarily in the form of sugars. However, within the fungus, most carbon is stored in lipids that are transported throughout the mycelium. 

Prof. WANG Ertao and his colleagues at CAS Center of Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), show that the AM fungus Rhizophagus irregularis is a fatty acid auxotroph and fatty acids synthesized in the host plant are transferred to the fungus during AM symbiosis. They find that the transfer is dependent on the RAM2 (Required for Arbuscular Mycorrhization 2) and peri-arbuscular membrane-localized ATP binding cassette (ABC) transporter-mediated plant lipid export pathway. 

The study further proves that fatty acids synthesized in plants also can be transferred to the pathogenic fungus Golovinomyces cichoracerum. Plants defective in fatty acid biosynthesis are impaired in AM symbiosis and show defects in colonization by the pathogenic G. cichoracerum. 

Overall, this novel mechanism of the mutualistic mycorrhizal reveals that pathogenic fungi similarly recruit the fatty acid biosynthesis program to facilitate host invasion, and regulating fatty acid availability to fungus might provide an effective tool to control pathogenic fungus infection in crops. 

The study entitled “Plants transfer lipids to sustain colonization by mutualistic mycorrhizal and parasitic fungi” has been published online in Science on Jun. 8, 2017.

The study was supported by the 973 National Key Basic Research Program in China, the Ministry of Agriculture of China for Transgenic Research, the Natural Science Foundation of China, and the China Postdoctoral Science Foundation.

Article Website:
http://science.sciencemag.org/content/early/2017/06/07/science.aam9970.full

A new model shows that host plants synthesize fatty acid and transfer to AM fungus by STR/STR2 transporter.
 (Image by Dr. WANG’s lab)

CONTACT:
JIANG Yina, Ph.D.
National Key Laboratory of Plant Molecular Genetics
CAS Center of Excellence in Molecular Plant Sciences
Shanghai Institute of Plant Physiology and Ecology
Chinese Academy of Sciences
300 Fenglin Road
Shanghai 200032
Phone: (86) 21-54924079
Email: ynjiang@aliyun.com