Ustilago maydis Nit2 Regulates Nitrate Utilisation During Biotrophy and Affects Amino Acid Metabolism of Galls Under Nitrogen Depletion.

In previous work, we have shown that the transcription factor Nit2 plays a major role in the utilisation of non-favoured nitrogen sources like nitrate, minor amino acids or nucleobases in saprotrophic sporidia of the basidiomycete corn smut fungus Ustilago maydis. Addressing the knowledge gap regarding how filamentous phytopathogens adapt to nitrogen limitation in the host plant, we employed Δnit2 mutants in the natural FB1 × FB2 background to identify Nit2-regulated genes during biotrophy. We further investigated the impact of Nit2 on the physiology of leaf galls in nitrogen-replete versus nitrogen-limited host plants by comparative RNA-Seq and metabolic steady state analysis.