Transcriptomic Analysis Reveals the Molecular Adaptation of Three Major Secondary Metabolic Pathways to Multiple Macronutrient Starvation in Tea (Camellia sinensis)

Abstract

Tea (Camellia sinensis (L.) O. Kuntze) is a widely consumed beverage. Lack of macronutrients is a major cause of tea yield and quality losses. Though the effects of macronutrient starvation on tea metabolism have been studied, little is known about their molecular mechanisms. Hence, we investigated changes in the gene expression of tea plants under nitrogen (N), phosphate (P), and potassium (K) deficient conditions by RNA-sequencing. A total of 9103 differentially expressed genes (DEG) were identified. Function enrichment analysis showed that many biological processes and pathways were common to N, P, and K starvation. In particular, cis-element analysis of promoter of genes uncovered that members of the WRKY, MYB, bHLH, NF-Y, NAC, Trihelix, and GATA families were more likely to regulate genes involved in catechins, l-theanine, and caffeine biosynthetic pathways. Our results provide a comprehensive insight into the mechanisms of responses to N, P, and K starvation, and a global basis for the improvement of tea quality and molecular breeding.

Metabolome and RNA-seq Analysis of Responses to Nitrogen Deprivation and Resupply in Tea Plant (Camellia sinensis) Roots

“…Furthermore, the contents of caffeine, theobromine, and theophylline decreased during N deprivation and resupply, indicating that their syntheses were suppressed by N deprivation, and they had poor adaptability to N resupply. Caffeine synthesis and degradation related-genes showed an overall decrease in expression, implying that caffeine metabolism was not active in N deficiency and resupply, which was consistent with a previous study (Su et al, 2020). This may also be related to the low synthesis of caffeine in C. sinensis roots.…”

“…Furthermore, the favorable effect of ammonium on tea plant can be weakened by nitrate (Ruan et al, 2019). As a primary nutrient, N stress can influence the metabolism of tea plant, especially C and N metabolism, and further lead to changes of the synthesis of secondary metabolites like theanine and polyphenols in tea plant (Su et al, 2020;Liu et al, 2021a).…”

HAK/KUP/KT family potassium transporter genes are involved in potassium deficiency and stress responses in tea plants (Camellia sinensis L.): expression and functional analysis

“…Among these substances, catechins, theanine, and caffeine are the most important characteristic secondary metabolites in tea bud and leaf, which endow the tea with a rich taste and many health benefits [ 1 – 3 ]. Generally, the composition of the tea bud and young leaf is greatly influenced by many factors, such as the tea plant cultivar, nutrition status and environmental factors [ 4 – 7 ]. Out of these factors, mineral nutrition, especially nutrition of potassium, considerably affects the growth and development of tea plants [ 8 ].…”

Specialized Metabolites and Valuable Molecules in Crop and Medicinal Plants: The Evolution of Their Use and Strategies for Their Production

“…Quite severe weather changes have occurred in the last ten years and the impacts of climate change appear to deeply affect crop productivity. Several studies [ 25 , 49 , 50 , 51 , 52 ] documented the effect of unexpected heat, cold, light, drought and salinity stresses on plant metabolism and growth, which often is severely impaired [ 53 , 54 , 55 , 56 , 57 ]. The evaluation of the impact of changing environmental factors on plants, as well as the knowledge of plant responses, is helpful to design a potential strategy to minimize this impact by selecting species and varieties with favourable traits able to confer adaptation and even resistance.…”

“…The maintenance of a stable accumulation of molecules is an important prerequisite for commercially crops, especially for those crops consumed as food or used in beverages. Su et al, 2020 [ 51 ], highlighted the impact of nutrient starvation on tea quality as mainly due to the number of specific compounds accumulated in the leaves of the tea plant ( Camellia sinensis ) during its cultivation. The single effect of N, P and K nutrient starvation on the biosynthesis of key flavour determinants of tea was investigated by RNA sequencing.…”