Nitrogen Input Alters Root Exudate Profiles and Nitrification Inhibition in Teosinte and Maize

Teosinte (Zea mays subsp. mexicana) has been proposed as a potential source of biological nitrification inhibition (BNI), yet how nitrogen (N) inputs modulate its exudate chemistry and associated nitrification processes remains unclear. We compared teosinte with three maize cultivars under N-deficient and N-replete conditions, integrating non-targeted metabolomics of root exudates, qPCR of rhizosphere amoA genes, and pure-culture assays with Nitrosomonas europaea. N fertilisation enhanced total root exudation and reprogrammed the teosinte metabolome toward amino and phenolic acids, with histidine, glutamic acid, ferulic acid, and vanillic acid being markedly enriched. These compositional shifts coincided with reduced archaeal amoA abundance in teosinte (and Zhengdan958) but increased levels in Ye478 and Qi319. In culture, exudates from N-fed teosinte strongly inhibited N. europaea ammonia oxidation (~ 63%), whereas exudates from modern maize, except for Zhengdan958, showed little effect. Histidine, vanillic acid and ferulic acid reproduced inhibition in targeted assays, implicating them as candidate BNIs likely acting through copper chelation and phenolic interference. Collectively, these findings demonstrate that N availability reshapes teosinte exudate chemistry, thereby strengthening nitrification suppression through specific amino- and phenolic-acid release. Leveraging these wild traits could inform sustainable N management and enhance nitrogen-use efficiency in maize-based agroecosystems.