open access

https://hdl.handle.net/2115/43031

ATP-Dependent but Proton Gradient-Independent Polyphosphate-Synthesizing Activity in Extraradical Hyphae of an Arbuscular Mycorrhizal Fungus

英語

2009-11

American Society for Microbiology

Applied and Environmental Microbiology

75(22)

7044-7050

Arbuscular mycorrhizal fungi benefit their host plants by supplying phosphate obtained from the soil. Polyphosphate is thought to act as the key intermediate in this process, however, little is currently understood about how polyphosphate is synthesized or translocated within arbuscular mycorrhizas. Glomus sp. HR1 was grown with marigold in a mesh bag compartment system, and extraradical hyphae were harvested and fractionated by density gradient centrifugation. Using this approach, three distinct layers were obtained: Layers 1 and 2 were composed of amorphous and membranous materials, together with mitochondria, lipid bodies, and electron-opaque bodies, and layer 3 was composed mainly of partially broken hyphae and fragmented cell walls. The polyphosphate kinase/luciferase system, a highly sensitive polyphosphate detection method, enabled the detection of polyphosphate-synthesizing activity in layer 2 in the presence of ATP. This activity was inhibited by vanadate but not by bafilomycin A1 or a protonophore, suggesting that ATP may not energize the reaction through H+-ATPase but act as a direct substrate in the reaction. This report represents the first demonstration that AM fungi possess polyphosphate-synthesizing activity that is localized in the organelle fraction and not in the cytosol or at the plasma membrane.

学術雑誌論文

Accepted Manuscript

© 2009 American Society for Microbiology

0099-2240