Exploring the Effects of Magnesium Deficiency on the Quality Constituents of Hydroponic-Cultivated Tea (Camellia sinensis L.) Leaves

Abstract

Magnesium (Mg) plays important roles in photosynthesis, sucrose partitioning, and biomass allocation in plants. However, the specific mechanisms of tea plant response to Mg deficiency remain unclear. In this study, we investigated the effects of Mg deficiency on the quality constituents of tea leaves. Our results showed that the short-term (7 days) Mg deficiency partially elevated the concentrations of polyphenols, free amino acids, and caffeine but decreased the contents of chlorophyll and Mg. However, long-term (30 days) Mg-deficient tea displayed decreased contents of these constituents. Particularly, Mg deficiency increased the index of catechins' bitter taste and the ratio of total polyphenols to total free amino acids. Moreover, the transcription of key genes involved in the biosynthesis of flavonoid, caffeine, and theanine was differentially affected by Mg deficiency. Additionally, short-term Mg deficiency induced global transcriptome change in tea leaves, in which a total of 2522 differentially expressed genes were identified involved in secondary metabolism, amino acid metabolism, and chlorophyll metabolism. These results may help to elucidate why short-term Mg deficiency partially improves the quality constituents of tea, while long-term Mgdeficient tea may taste more bitter, more astringent, and less umami.

The Impact of Magnesium on the Growth, Physiology and Quality of Tea (Camellia sinensis L.) Plants under Acid Stress

“…In our study, we observed an increase in chlorophyll content that positively correlated with Mg concentration, while acid stress led to a decrease. Notably, Mg deficiency generated a significant reduction in chlorophyll content within 30 days, indicating that the two are tightly linked, as previously reported [29]. In agricultural practice, reduced chlorophyll content results in interveinal chlorosis in mature plant leaves [36], although our experimental plants displayed no significant chlorosis at any time.…”

“…The concentration of chlorophyll in fresh mature leaves was determined using a modified version previously described [29]. In brief, the leaves were washed and dried and primary veins were removed, followed by chopping into small pieces and placement (0.20 g) in a 25 mL volumetric flask.…”

Evaluation of Environmental Factor Effects on the Polyphenol and Flavonoid Content in the Leaves of Chrysanthemum indicum L. and Its Habitat Suitability Prediction Mapping

“…Additionally, the variations in the content of the identified antioxidant compounds were explained by the variations in exchangeable magnesium, cation exchangeable capacity, annual precipitation (BIO12), pH, annual mean temperature, precipitation, annual mean temperature (BIO01), clay, bulk density, and topographic wetness index (TWI) based on analysis of variance (ANOVA), as shown in Table 3 . Magnesium deficiency in plants can cause a decrease in total phenolic content [ 36 ], and exchangeable magnesium is crucial for generating the main phenolic compounds responsible for the antioxidant activity of C. indicum . From this result, cation exchange capacity, which shows the ability of soil to hold and supply nutrients such as magnesium and calcium, is also an important parameter for plant growth, as mentioned in previous studies [ 37 , 38 ].…”

The power of magnesium: unlocking the potential for increased yield, quality, and stress tolerance of horticultural crops

“…(2022) demonstrated a positive correlation between Mg 2+ content and sugar accumulation in navel oranges, substantiating the role of Mg 2+ in sugar synthesis. Furthermore, Li et al. (2021) investigated Camellia sinensis and revealed that adequate Mg 2+ levels enhance the production of volatile compounds, thus improving the quality constituents of Hydroponic-Cultivated Tea.…”