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• Transcriptome, translatome, and metabolome were used to analyse tea etiolation. • Ribosome profiling reveals carbon and phytohormone metabolism mediate leaf etiolation. • HY5 inhibited chlorophyll and flavonoids metabolism in etiolated leaf. • Changes in gene structure between EL and GL influence their gene expression. Albino tea plants (Camellia sinensis , Atps) are among the most attractive germplasm resources because of their unique phenotype and flavor. Although previous studies have extensively investigated the transcriptional and metabolic mechanisms in Atps, the lack of research at the translational level hinders the understanding of translation control and multi-omics integration. Here, we integrated the transcriptome, translatome, and metabolome to study the global translation and its effect on the metabolic characteristics of Atps. Comparative analysis of RNA-seq and Ribo-seq datasets indicated that 4,295 genes were expressed as synergic responses in etiolated leaves and were mainly enriched in the carbon metabolism and phytohormone pathways. Further integration-omics analyses revealed that the HY5 gene was upregulated at both the transcription and translation levels and repressed chlorophyll biosynthesis and flavonoids metabolism due to low levels of indole acetic acid and auxin response factors. Moreover, sequence characterizations (guanine-cytosine (GC) content, length, and normalized minimal free energy (NMFE)) highly influenced the translational efficiencies (TE) of genes and upstream open reading frames (uORFs), and a higher quantity of uORFs and TE were observed in EL, inhibiting the expression of downstream genes. In summary, we demonstrated that translation regulation contributes to causing leaf color variation and provided a valuable method for exploring the potential regulatory mechanisms controlling phytohormones that affect crop quality using multi-omics technology. [Display omitted] [ABSTRACT FROM AUTHOR]

In the preharvest stage of tea leaves, the stress exposure including drought, cold, light, and insect, could promote the good taste of tea. In the postharvest stage of tea leaves, the stress exposure including wounding, drying, and low-temperature, could promote the good aroma of tea. • This review summarizes the relationships among stress, metabolites, and quality in tea leaves. • The pre-harvest and post-harvest factors such as stress and manufacturing, both change the environment to stimulate fresh tea leaves and influence the tea quality. • Stress exposure affects secondary metabolites such as sugar, amino acid, catechin, and aroma compound to improve tea quality including the taste and aroma. • The knowledge from this review facilitates a new view of utilizing stress for leaf-use crop stress research. Environmental stress can greatly influence the accumulation of primary and secondary metabolites in tea leaves, thereby affecting tea quality. Metabonomics technology has enabled a clear understanding of stress-induced changes in plant metabolite profiles. However, few studies have actually brought this knowledge into the tea production process. This review proposes a feasible strategy to link the relationships among stress factors, metabolites, and tea quality. First, we extensively review a number of studies that focused the effects of stress, namely, cold, drought, intense light, and insect herbivory, on soluble sugars, free amino acids, catechins, caffeine, and aroma compounds in tea leaves. These studies included single or multiple artificial stress conditions (e.g., wounding, drying, and low temperature) during pre-harvest plant growth and post-harvest processing, which induced the production of different types of volatile compounds, such as fatty acid derivatives, amino acid derivatives, terpenoid derivatives, phenylpropanoids, and benzenoids. As environmental stress conditions and tea manufacturing have similar effects on leaves, tea manufacturing was considered as an exposure to multiple stress factors during tea production. Finally, our review aims to provide a useful understanding of plant metabolism based on which, tea leaves may be purposely exposed to controlled stress conditions during tea manufacturing as a novel strategy for scientifically improving tea quality. [ABSTRACT FROM AUTHOR]

• No negative effects occurred for SAR (pH 3.5 and pH 4.5). • SAR (pH 2.5) reduced chloroplasts and damaged the outer leaf layers. • SAR (pH 2.5) altered genes related to photosynthesis and various metabolic pathways. • Plants respond to SAR stress by mechanisms of resistance, avoidance, and escape. Tea plants (Camellia sinensis (L.) O. Kuntze), which are typically cultivated in high-elevation mountainous regions in southern China, are severely affected by acid rain. Our recent study indicated that simulated acid rain (SAR) at pH 2.5 produced necrotic spots on the leaf surface, impaired plant development by inhibiting photosynthesis and the antioxidant defense system, and caused metabolic disorders. In contrast, a pH of 4.5 had no toxic effects on tea seedlings. However, molecular-level evidence for these conclusions is still lacking. In this study, we explored the changes in leaf micromorphology under different SAR treatments using electron microscopy, and presented the first case study on the systemic responses of the tea leaf transcriptome to SAR. An examination of leaves using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that SAR (pH 4.5 and pH 3.5) did not impair the epidermis or chloroplast structures, but SAR (pH 2.5) reduced the number of chloroplasts, corroded epicuticular wax and trichomes, and altered stomatal density and size. Transcriptomic analysis revealed that the expression of multiple genes related to photosynthesis and carbohydrate, nitrogen, and sulfur metabolism were altered under SAR. Additionally, epicuticle wax biosynthesis and plant hormone signal transduction pathways were found to significantly influenced by high-acidity SAR. Taken together, our results suggest that tea plant responses to intense SAR stress incorporate three aspects: (1) stress resistance via altering metabolic pathways to enable survival; (2) stress avoidance via restraining uncontrolled non-stomatal gas exchange; and (3) stress escape via redistributing nitrogen from stress damaged leaves. These findings provide valuable insights into plant responses to acid rain stress. [ABSTRACT FROM AUTHOR]

• The research progress and classification of Atps were summarized. • The expression pattern of protochlorophyllide oxidoreductase (POR) is one of the crucial factors affecting chlorophyll biosynthesis and chloroplast biogenesis. • Epigenetics, tea processing, health benefits, and whole-genome resequencing are potential areas for study Atps. The distinct historical background and tea flavor, including high umami taste and low astringency, make the albino tea plants (Atps) stick out from the tea plant (Camellia sinesnis). The decipherment of genes, enzymes, and metabolites involved in these processes is still significantly lagging, which lays an obstacle for molecular plant breeding and commercialized production. With the popularity of high-throughput omics technology, 'single level' or 'multi-level'-based research theory have emerged as powerful tools for revealing the mechanism of characteristic metabolite accumulation and pigment transformation. Thus, it is pivotal to summarize and introduce these advances in facilitating gene identification of critical pathways in the Atps. In this review, we systematically arranged the history and classification of Atps, detailed their strategies for stress response and the metabolic pattern of L-theanine and catechins. Further, reference the successful examples of model plants, we concentrating on the recent advances in omics technology applied to the Atps. Finally, we prospect the promising development areas of the Atps. [ABSTRACT FROM AUTHOR]