Accumulation of Amino Acids and Flavonoids in Young Tea Shoots Is Highly Correlated With Carbon and Nitrogen Metabolism in Roots and Mature Leaves

Abstract

The quality of tea product and the metabolism of quality-related compounds in young shoots are significantly affected by the nitrogen(N) supply. However, little is known of the metabolic changes that take place in tea roots and mature leaves under different supplies, which has a large effect on the accumulation of quality-related compounds in young shoots. In this study, young shoots, mature leaves, and roots under different N conditions were subjected to metabolite profiling using gas chromatography and ultraperformance liquid chromatography, coupled with quadrupole time-of-flight mass spectrometry. The contents of free amino acids (e.g., theanine and glutamate) involved in N metabolism were significantly greater under high N than under low N, while a high N supply reduced soluble sugars (e.g., glucose) in all three tissues. Organic acids (e.g., malate, fumarate, α-ketoglutatare, and succinate) involved in tricarboxylic acid cycle remarkably increased as the nitrogen supply increased, which confirms that carbon (C) allocation was restricted by increasing the nitrogen supply, especially in mature leaves. RT-PCR results indicated that gene expression related to nitrogen assimilation significantly increased in roots with increasing nitrogen supply, which had a significant positive relationship with the level of free amino acids in young shoots. In addition, the expression of most genes involved in flavonoid synthesis was significantly upregulated under conditions of low nitrogen supply relative to high nitrogen supply in young shoot and roots. These data suggest that enhanced assimilation of N in tea roots and the coordinated regulation of C (sugars, organic acids, and flavonoids) and N(amino acids) in mature leaves can lead to a high accumulation of amino acids in young shoots. Furthermore, as the N supply increased, more C was partitioned into compounds containing N in mature leaves and roots, resulting in a decrease in flavonoids in young shoots. In conclusion, the accumulation of amino acids and flavonoids in young tea shoots is highly correlated with carbon and nitrogen metabolism in roots and mature leaves.

Comparative metabolomics reveals complex metabolic shifts associated with nitrogen-induced color development in mature pepper fruit

“…Flavonoids are synthesized from phenylalanine via phenylpropanoid and flavonoid pathways ( Tohge et al., 2017 ; Liu et al., 2020 ). Previous studies have found that expression of flavonoid biosynthesis pathway genes is affected by nutrient depletion ( Liu et al., 2021 ). N deficiency could decrease chlorophyll content and photosynthesis ( Li et al., 2021 ).…”

Characterization of the Difference between Day and Night Temperatures on the Growth, Photosynthesis, and Metabolite Accumulation of Tea Seedlings

“…On the contrary, the 10 °C DIF treatment was beneficial for the amino acid accumulation in the tea seedlings. It has been widely understood that amino acid biosynthesis was associated with nitrogen metabolism [ 51 , 52 ]. The significantly enriched pathway of nitrogen metabolism provided a sufficient nitrogen source for the biosynthesis of nitrogen compounds, where the carbonic anhydrase (CA) and nitrate/nitrite transporter (Nrt) has played indispensable roles in the utilization of carbon dioxide and the transfer of carboxylic acid [ 53 , 54 ].…”

Molecular Link in Flavonoid and Amino Acid Biosynthesis Contributes to the Flavor of Changqing Tea in Different Seasons

“…Its composition and content were affected by environmental factors, such as light, temperature, and soil fertilizers, etc. [ 7 , 31 ]. In Changqing tea, the free amino acids in spring was 63–89 mg/g, which was higher than albino tea cultivars Xiaoxueya of 41 mg/g and Baiye 1 of 35 mg/g, Huangshanbaicha of 71 mg/g during the albinostic stage, as well as higher than green cultivars of Zhenong 113 of 30 mg/g [ 27 , 32 ].…”