NADPH Dehydrogenase Gene Regulates Energy Distribution and Fatty Acid Metabolism During Fruiting Body Formation in...

Nicotinamide adenine dinucleotide phosphate (NADPH) dehydrogenase is an oxidoreductase involved in many physiological processes and metabolic pathways. However, its role in filamentous fungal physiology is still unclear. In the present study, three canonical NADPH dehydrogenase genes (Panph1, Panph2, and Panph3) in the fungus Podospora anserina were deleted, and multiple mutants were constructed. Results show a significantly increased number of fruiting bodies in the NADPH dehydrogenase mutant, with the nph^ΔΔΔ triple mutant exhibiting higher sensitivity to oxidative stress, suggesting an active-site protein misfolding. Specifically, the antioxidant genes Nox and CAT in the WT were significantly down-regulated, confirming NADPH availability; however, in the NADPH mutant, these genes were significantly upregulated (p ≤ 0.001) as a response to nullify the constraint imposed by NADPH deletion and alleviate oxidative stress. Furthermore, an increase in substrate-level phosphorylation compensated for a significant decrease in oxidative phosphorylation due to NADPH gene deletion. The NADPH/NADP⁺ ratio, a driving force for the intracellular redox potential, showed a significant increase in the nph^ΔΔΔ triple mutant. Meanwhile, the NADPH mutant inhibited the β-oxidative pathway, decreasing fatty acid degradation, but promoted fatty acid biosynthesis, reflecting the role of NADPH in the metabolic programming of cellular respiration and energy utilization processes in fungi. Our study provides genetic evidence for the role of the NADPH dehydrogenase gene in oxidative defence and energy metabolism in P. anserina.