The GC-TOF/MS-based Metabolomic Analysis Reveals Altered Metabolic Profiles in Nitrogen-Deficient Leaves and Roots of Tea Plants (Camellia sinensis L.)

Background: Nitrogen (N) fertilizer is commonly considered as one of the most omportant limiting factors in the agricultural production. As a result, modern tea production, a large amount of N fertilizer is used to improve the yield. Unfortunately, the large amount of N fertilizer input has led to increased plant nitrogen-tolerance and decreased amplitude of yield improvement, which results in significant N loss, energy waste and environment pollution.However, the effects of N-deficiency on the metabolic profiles of leaves and roots are not well understood. Results: : In the study, seedlings of Camellia sinensis (L.) O. Kuntze cv. Chunlv 2 were treated with 3 mM NH 4 NO 3 （as Control）or without NH 4 NO 3 （as N-deficiency）for 4 months by sandy culture. The results suggested the N-deficiency induced tea leaf chlorosis, impaired biomass accumulation, decreased the leaf chlorophyll content and N absorption compared to Control. The untargeted metabolomics based on GC-TOF/MS approach revealed discrimination of the metabolic profiles between N-deficient tea leaves and roots. The identification and classification of the altered metabolites indicated the N deficiency upregulated the relative abundances of most phenylpropanoids, organic acids while downregulated the relative abundances of most amino acids in the tea leaves. Differentially, N-deficiency induced the accumulation of most carbohydrates, organic acids and amino acids in the tea roots. The potential biomarkers screened in the N-deficient leaves compared to Control reflected the N deficiency reduced the tea quality. Unlike the N-deficient leaves, the potential biomarkers in the N-deficient roots implied an improved stress response. Conclusions: : The results demonstrated the N deficiency had different effects on the primary and secondary metabolic alteration of tea leaves and roots. The findings of the study will facilitate a comprehensive understanding of the N-deficient tea plants and provide a valuable reference for the optimized N nutrient management in the tea plantations.