The root endophytic fungus Piriformospora indica requires host cell death for proliferation during mutualistic symbiosis with barley

• DOI: 10.1073/pnas.0605697103
• Publication Date: 2006-11-21T01:57:31Z
• Authors: Sachin Deshmukh; Ralph Hückelhoven; Patrick Schäfer; Jafargholi Imani; Monica Sharma; Michael Weiss; Frank Waller; Karl-Heinz Kogel
• Keywords: Endophyte; Chlamydospore

Fungi of the recently defined order Sebacinales (Basidiomycota) are involved in a wide spectrum mutualistic symbioses (including mycorrhizae) with various plants, thereby exhibiting unique potential for biocontrol strategies. The axenically cultivable root endophyte Piriformospora indica is model organism this fungal order. It able to increase biomass and grain yield crop plants. In barley, induces local systemic resistance diseases abiotic stress. To elucidate lifestyle P. , we analyzed its symbiotic interaction endophytic development barley roots. We found that colonization increases tissue maturation. tip meristem showed no colonization, elongation zone mainly intercellular colonization. contrast, differentiation was heavily infested by inter- intracellular hyphae chlamydospores. majority were present dead rhizodermal cortical cells became completely filled some cases, penetrated built meshwork around plasmolyzed protoplasts, suggesting fungus either actively kills or senses undergoing endogenous programmed cell death. Seven days after inoculation, expression BAX inhibitor-1 ( HvBI-1 ), gene capable inhibiting plant death, attenuated. Consistently, proliferation strongly inhibited transgenic overexpressing GFP-tagged HvBI-1, which shows requires host death differentiated suggest interferes program form