Tea plant (Camellia sinensis) could accumulate fluorine (F) in leaves efficiently.Fresh tea leaves are always regarded as the culprit of excess F in Sichuan dark tea (SDT).The present study evaluated F level in different tea cultivars and young shoots to select the appropriate production raw materials.Results showed that F level varied greatly among tea cultivars, from 65.9 to 821.6 mg kg -1 in the young shoots with five expanded leaves and increased with the age of young shoots.Young shoots with up to seven leaves of Zhongcha 108 or Fuding Dabaicha had the lower F level and could be used as the appropriate raw materials to produce Sichuan dark tea.
Despite the worldwide consumption and high economic importance of tea, the plant (Camellia sinensis) is not well studied in molecular biology. Under the few circumstances in which the plant is studied, C. sinensis flowers, which are important for reproduction and cross-breeding, receive less emphasis than investigation of its leaves or roots. Using high-throughput Illumina RNA sequencing, we analyzed a C. sinensis floral transcriptome, and 26.9 million clean reads were assembled into 75,531 unigenes averaging 402 bp. Among them, 50,792 (67.2%) unigenes were annotated with a BLAST search against the NCBI Non-Redundant (NR) database and 10,290 (16.67%) were detected that contained one or more simple sequence repeats (SSRs). From these SSR-containing sequences, 2,439 candidate SSR markers were developed and 720 were experimentally tested, validating 431 (59.9%) novel polymorphic SSR markers for C. sinensis. Then, a consensus SSR-based linkage map was constructed that covered 1,156.9 cM with 237 SSR markers distributed in 15 linkage groups. Both transcriptome information and the genetic map of C. sinensis presented here offer a valuable foundation for molecular biology investigations such as functional gene isolation, quantitative trait loci mapping, and marker-assisted selection breeding in this important species.
Salt stress is one of the abiotic stresses affecting crop quality and yield, and the application of exogenous brassinosteroids (BRs) can be used in response to salt stress. However, the function of BR in tea plants under salt stress remains to be elucidated. This study investigated the effects of exogenous spraying of BR on the malondialdehyde, soluble sugar, soluble protein, and antioxidant enzyme activities in tea plants under salt stress and explored the expression changes in genes related to the synthesis pathways of proline and secondary metabolites (flavonoids and theanine). The results show that 200 mM NaCl solution inhibits the physiology of tea plants, but 0.2 mg/L BR could partially reduce the damage by increasing photosynthetic pigments, osmoregulatory substances (such as soluble sugar, soluble protein, and proline), and the activity of antioxidant enzymes (including peroxidase, catalase, and superoxide dismutase), while decreasing the malondialdehyde content in salt-stressed leaves. The qRT-PCR experiment also shows that the genes related to the synthesis pathways of proline and secondary metabolites (flavonoids and theanine) were upregulated under salt stress, and the proline degradation genes were downregulated, thus promoting the accumulation of proline under salt stress in both varieties. When tea plants were subjected to salt stress, the expression of genes related to the synthesis of secondary metabolites was regulated accordingly to resist salt stress. Moreover, spraying BR had an obvious effect on improving the salt tolerance of tea plants. Therefore, exploring a way to improve the salt tolerance of tea trees provides a reference for the subsequent study of its salt tolerance mechanism, which is of great significance for expanding the introduction area of tea trees, increasing the planting area of tea trees, and improving the yield and quality of tea.
Abstract ZY, HYZ and CH-1 are three characteristic tea varieties with different shoot colors. However, there is a lack of karyotype analysis of these characteristic tea varieties. In this experiment, the differences of cytological parameters of three characteristic tea varieties, and the control variety FDDB, were analyzed. The results showed that significant differences of the average arm ratio, relative length, karyotype asymmetry index and the karyotype formula were found among the three characteristic tea varieties as well as the control variety FDDB. Moreover, only ZY’s karyotype type was 2B, while the three other varieties all were 2C. Among them, HYZ was the most evolved and closed to FDDB, while CH-1 and ZY were very different from FDDB and evolved more primitive than HYZ. HYZ was the most evolved, and ZY was relatively primitive. PCA analysis indicated that the notable differences were found between FDDB and two characteristic tea varieties (ZY and CH-1), while HYZ is relatively close to FDDB. This findings revealed the variation of chromosomes among different color varieties at the cytological level, and provided a certain theoretical basis for the study of genetic variation and diversity of tea resources.
The infusion regulation of main quality component in tea was analyzed by using an oscillator to imitate the process of pouring boiling water into tea to study the effect of vibration after pouring boiling water into tea on quality of tea soup.The results showed that the process of pouring boiling water into tea could enhance the infusion rate of main quality components in tea soup,shorten the time to reach their highest concentration and have no obvious effect on the ratio of phenol/ammonia.
Nitrogen (N) is a key regulator in the growth of tea plants and the synthesis of amino acids (AAs) and related secondary metabolites, thus affecting the yield and quality of tea leaves. Increased N fertilization significantly improves the yield and quality of tea plants, but applying excess nitrogen wastes resources and causes pollution problems. Herein, we employed morphological, physiological, metabolomic, and RNA-seq methods to study the response of ‘Ziyan’ roots to high N. High N supply induced an increase in arginine (Arg), asparagine (Asn), and glutamine (Gln) in roots and simultaneously decreased sucrose, polyphenols, and caffeine contents. High N reduced the length, volume, number, and activity of the roots by 10.63%, 25.00%, 26.95%, and 14.50%, respectively, which inhibited ‘Ziyan’ root growth, probably by disturbing the regulation of carbon and nitrogen metabolism in the tea plant. According to the Kyoto Encyclopedia of Genes and Genome (KEGG) enrichment analysis, AAs, flavonoids, and flavonol-related pathways were relatively active after supplying high N. In addition, the transcriptome analysis identified NRT1/PTR and GOGAT as key genes, and the transcription factors (e.g., AP2/ERF, MYB, and WRKY) and auxins were actively involved in the high N stress response of ‘Ziyan’ roots. These findings will help us understand the adaptive mechanism of high N supply in tea tree roots and provide a reference for guiding the fertilization of ‘Ziyan’ tea plants.
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