The GC-TOF/MS-based Metabolomic analysis reveals altered metabolic profiles in nitrogen-deficient leaves and roots of tea plants (Camellia sinensis)

Abstract

Background Nitrogen (N) fertilizer is commonly considered as one of the most important limiting factors in the agricultural production. As a result, a large amount of N fertilizer is used to improve the yield in modern tea production. 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 tea leaves and roots are not well understood. Results In this study, seedlings of Camellia sinensis (L.) O. Kuntze Chunlv 2 were treated with 3 mM NH4NO3 (Control) or without NH4NO3 (N-deficiency) for 4 months by sandy culture. The results suggested that N-deficiency induced tea leaf chlorosis, impaired biomass accumulation, decreased the leaf chlorophyll content and N absorption when they were compared to the Control samples. The untargeted metabolomics based on GC-TOF/MS approach revealed a discrimination of the metabolic profiles between N-deficient tea leaves and roots. The identification and classification of the altered metabolites indicated that N deficiency upregulated the relative abundances of most phenylpropanoids and organic acids, while downregulated the relative abundances of most amino acids in tea leaves. Differentially, N-deficiency induced the accumulation of most carbohydrates, organic acids and amino acids in tea roots. The potential biomarkers screened in N-deficient leaves compared to Control implied that N deficiency might reduce the tea quality. Unlike the N-deficient leaves, the potential biomarkers in N-deficient roots indicated an improved stress response might occur in tea roots. Conclusions The results demonstrated N deficiency had different effects on the primary and secondary metabolism in tea leaves and roots. The findings of this study will facilitate a comprehensive understanding of the N-deficient tea plants and provide a valuable reference for the optimized N nutrient management and the sustainable development in the tea plantations.

Differential Metabolic Responses of Lettuce Grown in Soil, Substrate and Hydroponic Cultivation Systems under NH4+/NO3− Application

“…However, a significant difference in lettuce metabolites with the control treatment was observed via PLS-DA analysis in hydroponic system. Under the control treatment, similar clustering has been observed in traditional Chinese herb ( Isatis indigotica ) [ 53 ] and tea plants, which showed more changes in their metabolomic profiles of plants as compared to N treatments according to OPLS-DA analysis [ 94 ]. Under the applied NH 4 + /NO 3 − ratio and the control treatments, NH 4 + and NO 3 − assimilation has produced nitric oxide, which influences reactive oxygen species (ROS) in plants and ultimately changes the metabolic changes in plants.…”

Adaptive responses of carbon and nitrogen metabolisms to nitrogen-deficiency in Citrus sinensis seedlings

“…Thus, N-deficiency-induced decreases of N assimilation and TSPs and increases of NH 4 + -N and NH 4 + -N/NO 3 − -N ratio might be responsible for N-deficiency-induced leaf senescence [ 53 ]. N-deficiency-induced decreases of N uptake and assimilation have also been found in N-deficient poplar [ 4 , 24 , 37 ], apple [ 32 ] and tea [ 25 ].…”

“…Glutamate pyruvate aminotransferase (GPT) and glutamate oxaloacetate aminotransferase (GOT), two enzymes involved in the process of ammonia transfer, play a key role in the biosynthesis of amino acids (AAs) [ 22 ]. Evidence shows that N-deficiency has a great impact on N uptake and assimilation and AA biosynthesis, which in turn affects C assimilation and ultimately limits crop growth [ 3 , 6 , 23 – 25 ]. However, the results on N-deficiency-induced alterations of N metabolisms in plants are not consistent.…”

“…Liu et al [ 34 ] reported that the abundances of FAAs such as aspartic acid (Asp), alanine (Ala), serine (Ser), isoleucine (Ile) and threonine (Thr) increased in response to low-N in common wild soybean (W1) roots, but they displayed a decreased trend in low-N-tolerant wild soybean (W2) roots, concluding that W2 could tolerate low-N by reducing AA biosynthesis and consequently lowering energy consumption. N-deficiency reduced the accumulation of most FAAs in leaves, but it increased the accumulation of FAAs in roots of tea [ 25 ].…”

“…However, a 7-day N-deficient treatment led to increased concentrations of sugars and TCA cycle intermediates in barley leaves [ 12 ]. N-deficiency increased the abundances of OAs in leaves and most sugars and OAs in roots of tea [ 25 ]. Low-N downregulated and upregulated TCA cycle in apple leaves and roots, respectively [ 32 ].…”