Search

Fluoride (F) can be absorbed from the environment and hyperaccumulate in leaves of Camellia sinensis without exhibiting any toxic symptoms. Fluoride exporter in C. sinensis (CsFEX) could transport F to extracellular environment to alleviate F accumulation and F toxicity, but its functional mechanism remains unclear. Here, combining with pH condition of C. sinensis growth, the characteristics of CsFEX and mechanism of F detoxification were further explored. The results showed that F accumulation was influenced by various pH, and pH 4.5 and 6.5 had a greater impact on the F accumulation of C. sinensis. Through Non-invasive Micro-test Technology (NMT) detection, it was found that F uptake/accumulation of C. sinensis and Arabidopsis thaliana might be affected by pH through changing the transmembrane electrochemical proton gradient of roots. Furthermore, diverse expression patterns of CsFEX were induced by F treatment under different pH, which was basically up-regulated in response to high F accumulation, indicating that CsFEX was likely to participate in the process of F accumulation in C. sinensis and this process might be regulated by pH. Additionally, CsFEX functioned in the mitigation of F sensitivity and accumulation strengthened by lower pH in Escherichia coli and A. thaliana. Moreover, the changes of H + flux and potential gradient caused by F were relieved as well in transgenic lines, also suggesting that CsFEX might play an important role in the process of F accumulation. Above all, F uptake/accumulation were alleviated in E. coli and A. thaliana by CsFEX through exporting F - , especially at lower pH, implying that CsFEX might regulate F accumulation in C. sinensis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Tea plant (Camellia sinensis (L.) O. Kuntze) is an important economic tea crop, but flowering will consume a lot of nutrients of C. sinensis, which will seriously affect the nutritional growth of C. sinensis. However, there are few studies on the development mechanism of C. sinensis flower, and most studies focus on a single C. sinensis cultivar., Results: Here, we identified a 92-genes' C. sinensis flower development core transcriptome from the transcriptome of three C. sinensis cultivars ('BaiYe1', 'HuangJinYa' and 'SuChaZao') in three developmental stages (bud stage, white bud stage and blooming stage). In addition, we also reveal the changes in endogenous hormone contents and the expression of genes related to synthesis and signal transduction during the development of C. sinensis flower. The results showed that most genes of the core transcriptome were involved in circadian rhythm and autonomous pathways. Moreover, there were only a few flowering time integrators, only 1 HD3A, 1 SOC1 and 1 LFY, and SOC1 played a dominant role in the development of C. sinensis flower. Furthermore, we screened out 217 differentially expressed genes related to plant hormone synthesis and 199 differentially expressed genes related to plant hormone signal transduction in C. sinensis flower development stage., Conclusions: By constructing a complex hormone regulation network of C. sinensis flowering, we speculate that MYC, FT, SOC1 and LFY play key roles in the process of endogenous hormones regulating C. sinensis flowering development. The results of this study can a provide reference for the further study of C. sinensis flowering mechanism., (© 2022. The Author(s).)

RAC/ROP gene (RACs) is a plant-specific small GTPases. RACs play an irreplaceable role in the tissue dynamics of cytoskeleton, vesicle transport and hormone signal transmission in plants. In the present study, a novel gene from RACs family, CsRAC1, was identified from tea [Camellia sinensis (L.) O. Kuntze]. CsRAC1 contained a 591-bp open reading frame and encoded a putative protein of 197 amino acids. Subcellular localization analysis in leaves of transgenic tobacco and root tips of Arabidopsis thaliana showed that CsRAC1 targeted the nucleus and cell membrane. The expression of CsRAC1 induced by abiotic stresses such as cold, heat, drought, salt and abscisic acid has also been verified by RT-qPCR. Further verification of biological function of CsRAC1 showed that overexpression of CsRAC1 increased the sensitivity of A. thaliana to salt stress, improved the tolerance of mature A. thaliana to drought stress, and enhanced the inhibition of ABA on seed germination of A. thaliana. In addition, the antioxidant system regulated by CsRAC1 mainly worked in mature A. thaliana. The results indicate that CsRAC1 is involved in the response of C. sinensis to salt, drought stress and ABA signaling pathway., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Water-soluble fluoride (WS-F) can be absorbed directly by tea plants from soil and comprises a major source of dietary F in tea consumers. To reveal the WS-F accumulation in tea leaves and assess WS-F health risks, 70 sets of samples including tea leaves at three maturity stages and corresponding topsoil were collected from Xinyang, China. The WS-F contents in tea samples and pH values in soil samples were determined., Results: The contents of WS-F in tea leaves exhibited a positive correlation with leaf maturity. The contents of WS-F in tea leaves showed a positive correlation with WS-F contents in the soil as the soil pH value exceeds 5. All the bud with two leaves samples, 84.29% of the third to sixth leaves samples, and 78.57% mature leaves samples in 5-min infusion tend to be no health threat. The leaching characteristics of WS-F from tea leaves were influenced by the leaf maturity and soaking time., Conclusion: Taking measures to control pH and WS-F concentration of plantations soil, as well as drinking tea infusion made from young leaves or reducing soaking time could decrease the WS-F health risk. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

Background: Xyloglucan endotransglycosylase/hydrolases (XTH) can disrupt and reconnect the xyloglucan chains, modify the cellulose-xyloglucan complex structure in the cell wall to reconstruct the cell wall. Previous studies have reported that XTH plays a key role in the aluminum (Al) tolerance of tea plants (Camellia sinensis), which is a typical plant that accumulates Al and fluoride (F), but its role in F resistance has not been reported., Results: Here, 14 CsXTH genes were identified from C. sinensis and named as CsXTH1-14. The phylogenetic analysis revealed that CsXTH members were divided into 3 subclasses, and conserved motif analysis showed that all these members included catalytic active region. Furthermore, the expressions of all CsXTH genes showed tissue-specific and were regulated by Al 3+ and F - treatments. CsXTH1, CsXTH4, CsXTH6-8 and CsXTH11-14 were up-regulated under Al 3+ treatments; CsXTH1-10 and CsXTH12-14 responded to different concentrations of F - treatments. The content of xyloglucan oligosaccharide determined by immunofluorescence labeling increased to the highest level at low concentrations of Al 3+ or F - treatments (0.4 mM Al 3+ or 8 mg/L F - ), accompanying by the activity of XET (Xyloglucan endotransglucosylase) peaked., Conclusion: In conclusion, CsXTH activities were regulated by Al or F via controlling the expressions of CsXTH genes and the content of xyloglucan oligosaccharide in C. sinensis roots was affected by Al or F, which might finally influence the elongation of roots and the growth of plants., (© 2021. The Author(s).)

Nitric oxide (NO) as a momentous signal molecule participates in plant reproductive development and responds to various abiotic stresses. Here, the inhibitory effects of the NO-dominated signal network on the pollen tube growth of Camellia sinensis under low temperature (LT) were studied by microRNA (miRNA) omics analysis. The results showed that 77 and 71 differentially expressed miRNAs (DEMs) were induced by LT and NO treatment, respectively. Gene ontology (GO) analysis showed that DEM target genes related to microtubules and actin were enriched uniquely under LT treatment, while DEM target genes related to redox process were enriched uniquely under NO treatment. In addition, the target genes of miRNA co-regulated by LT and NO are only located on the cell membrane and cell wall, and most of them are enriched in metal ion binding and/or transport and cell wall organization. Furthermore, DEM and its target genes related to metal ion binding/transport, redox process, actin, cell wall organization and carbohydrate metabolism were identified and quantified by functional analysis and qRT-PCR. In conclusion, miRNA omics analysis provides a complex signal network regulated by NO-mediated miRNA, which changes cell structure and component distribution by adjusting Ca 2+ gradient, thus affecting the polar growth of the C. sinensis pollen tube tip under LT.

It is of great significance to explore the molecular mechanism of gametophytic sexual reproduction in the genetic improvement and breeding of tea plants [Camellia sinensis (L.) O. Kuntze]. Imported beta family members (IMBs) are a class of widely distributed nucleoplasmic transport receptor proteins in eukaryotes, affecting plant development and reproduction, and participating in flowering time and sexual reproduction. Still missing, though, is a thorough examination of IMB members in tea plants. Here, seven members of the IMB gene family were screened by a genome-wide investigation in tea plants. These members were scattered unevenly throughout five chromosomes. All of them contained the conserved KAP95 and HEAT Repeat domains. Additionally, the promoter regions of CsIMBs harbored cis-acting elements associated with plant hormones, light, and abiotic stress responses. In order to further confirm the function of CsIMBs in the sexual reproduction of tea plants, the expression patterns of CsIMBs in different flower development stages and the ovary (before and after pollination) were analyzed. The expression results highlighted that CsIMBs were related to the fertility and fruiting of tea plants. Furthermore, five of the seven CsIMBs (CsIMB1a, CsIMB1b, CsIMB2, CsIMB3a, and CsIMB3b) were found to be localized in the nucleus revealed by subcellular localization analysis. These results offer a comprehensive characterization of IMB genes as well as insights into the potential roles of CsIMBs participating in the gametophytic sexual reproduction of C. sinensis. [ABSTRACT FROM AUTHOR]

Tea plants [ Camellia sinensis (L.) O. Kuntze] are hyperaccumulators of fluoride (F), but excessive F will harm the photosynthesis and metabolic activities of tea plants. Potassium (K) is one of the essential macronutrients of tea plants, which can enhance the photosynthesis of tea plants and their stress resistance. However, there are fewer studies on K in the accumulation of F in tea plants. In this study, we set three K treatment concentrations of 0 mM, 5 mM, 10 mM and finally found that when the tea plants were treated with F, exogenously applied 5 mM K treatment increased chlorophyll content, photosynthesis, and antioxidant enzyme activity, and reduced the extent of cellular damage, where starch particles content was reduced and the interstices of the chloroplast grana layer were more compact. After K treatment, the F content of new shoots decreased, and the flow rate of absorption of K by roots under F treatment was significantly increased through the Non-invasive Micro-test Technology (NMT), and 5 mM K treatment could effectively stabilize the membrane potential of roots. In addition, after K treatment, the relative expression of the F exporter CsFEX in tea plants was significantly upregulated, while the stress resistance gene expression of CsHAKs in tea plants was downregulated. Above all, appropriate K application could effectively alleviate the hyperaccumulation and stress effects of F on tea plants. • Potassium could effectively alleviate the stress effect of fluoride on tea plants. • Potassium could promote the expression of CsFEX. • Potassium could reduce the content of fluoride in tea plant shoots. • Potassium could slow down the fluoride transport efficiency in tea plants. [ABSTRACT FROM AUTHOR]