A Tripartite Interaction among the Basidiomycete , N-Fixing Endobacteria, and Rice Improves Plant Nitrogen Nutrition.

Nitrogen (N) limits crop yield, and improvement of N nutrition remains a key goal for crop research; one approach to improve N nutrition is identifying plant-interacting, N-fixing microbes. JGTA-S1 is a basidiomycetous yeast endophyte of narrowleaf cattail (). JGTA-S1 could not convert nitrate or nitrite to ammonium but harbors diazotrophic (N-fixing) endobacteria () that allow JGTA-S1 to fix N and grow in a N-free environment; moreover, dinitrogen reductase was transcribed in JGTA-S1 even under adequate N. Endobacteria-deficient JGTA-S1 had reduced fitness, which was restored by reintroducing JGTA-S1 colonizes rice (), significantly improving its growth, N content, and relative N-use efficiency. Endofungal plays a significant role in increasing the biomass and ammonium content of rice treated with JGTA-S1; also, JGTA-S1 has better N-fixing ability than free-living and provides fixed N to the plant. Genes involved in N metabolism, N transporters, and -like transcription factors were upregulated in rice roots within 24 h of JGTA-S1 treatment. In association with rice, JGTA-S1 has a filamentous phase and only penetrated filamentous JGTA-S1. Together, these results demonstrate an interkingdom interaction that improves rice N nutrition.