Dataset Information

Stress Responses of Shade-Treated Tea Leaves to High Light Exposure after Removal of Shading.

ABSTRACT: High-quality green tea is produced from buds and young leaves grown by the covering-culture method, which employs shading treatment for tea plants (Camellia sinensis L.). Shading treatment improves the quality of tea, but shaded tea plants undergo sudden exposures to high light (HL) at the end of the treatment by shade removal. In this study, the stress response of shaded tea plants to HL illumination was examined in field condition. Chl a/b ratio was lower in shaded plants than nonshaded control, but it increased due to exposure to HL after 14 days. Rapid decline in Fv/Fm values and increases in carbonylated protein level were induced by HL illumination in the shaded leaves on the first day, and they recovered thereafter between a period of one and two weeks. These results revealed that shaded tea plants temporarily suffered from oxidative damages caused by HL exposure, but they could also recover from these damages in 2 weeks. The activities of antioxidant enzymes, total ascorbate level, and ascorbate/dehydroascorbate ratio were decreased and increased in response to low light and HL conditions, respectively, suggesting that the upregulation of antioxidant defense systems plays a role in the protection of the shaded tea plants from HL stress.

SUBMITTER: Sano S

PROVIDER: S-EPMC7154902 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Stress Responses of Shade-Treated Tea Leaves to High Light Exposure after Removal of Shading.

Sano Satoshi S Takemoto Tetsuyuki T Ogihara Akira A Suzuki Kengo K Masumura Takehiro T Satoh Shigeru S Takano Kazufumi K Mimura Yutaka Y Morita Shigeto S

Plants (Basel, Switzerland) 20200301 3

High-quality green tea is produced from buds and young leaves grown by the covering-culture method, which employs shading treatment for tea plants (Camellia sinensis L.). Shading treatment improves the quality of tea, but shaded tea plants undergo sudden exposures to high light (HL) at the end of the treatment by shade removal. In this study, the stress response of shaded tea plants to HL illumination was examined in field condition. Chl a/b ratio was lower in shaded plants ...[more]

PMID: 32121552

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Project description:BackgroundTea (Camellia sinensis) has long been consumed worldwide for its amazing flavor and aroma. Methyl jasmonate (MeJA), which acts as an effective elicitor among the plant kingdom, could mostly improve the quality of tea aroma by promoting flavor volatiles in tea leaves. Although a variety of volatile secondary metabolites that contribute to aroma quality have been identified, our understanding of the biosynthetic pathways of these compounds has remained largely incomplete. Therefore, information aboaut the transcriptome of tea leaves and, specifically, details of any changes in gene expression in response to MeJA, is required for a better understanding of the biological mechanisms of MeJA-mediated volatiles biosynthesis. Moreover, MeJA treatment could exaggerate the responses of secondary metabolites and some gene expression which offer a better chance to figure out the mechanism.ResultsThe results of two-dimensional gas-chromatograph mass-spectrometry showed that the terpenoids content in MeJA-treated tea leaves increased, especially linalool, geraniol, and phenylethyl alcohol. More importantly, we carried out RNA-seq to identify the differentially expressed genes (DEGs) related to volatiles biosynthesis pathways induced by MeJA treatment (0 h, 12 h, 24 h and 48 h) in tea leaves. We identified 19245, 18614, 11890 DEGs respectively in the MeJA_12h, MeJA_24 h and MeJA_48 h samples. The α-Lenolenic acid degradation pathway was firstly responded resulting in activating the JA-pathway inner tea leaves, and the MEP/DOXP pathway significantly exaggerated. Notably, the expression level of jasmonate O-methyltransferase, which is associated with the central JA biosynthesis pathway, was increased by 7.52-fold in MeJA_24 h tea leaves. Moreover, the genes related to the terpenoid backbone biosynthesis pathway showed different expression patterns compared with the untreated leaves. The expression levels of 1-deoxy-D-xylulose-phosphate synthase (DXS), all-trans-nonaprenyl-diphosphate synthase, geranylgeranyl reductase, geranylgeranyl diphosphate synthase (type II), hydroxymethylglutaryl-CoA reductase and 4-hydroxy-3-methylbut-2-enyl diphosphate reductase increased by approximately 2-4-fold.ConclusionsThe results of two-dimension gas-chromatography mass-spectrometry analysis suggested that exogenous application of MeJA could induce the levels of volatile components in tea leaves, especially the geraniol, linalool and its oxides. Moreover, the transcriptome analysis showed increased expression of genes in α-Lenolenic acid degradation pathway which produced massive jasmonic acid and quickly activated holistic JA-pathway inner tea leaves, also the terpenoid backbones biosynthesis pathway was significantly affected after MeJA treatment. In general, MeJA could greatly activate secondary metabolism pathways, especially volatiles. The results will deeply increase our understanding of the volatile metabolites biosynthesis pathways of tea leaves in response to MeJA.

Project description:BackgroundCold stress usually occurs in winter and is one of the most significant environmental factors restricting the growth of the tea plant as well as its geographical distribution.ObjectiveIt is necessary to identify the physiological and molecular mechanisms of plants under cold stress so that cold-tolerant crop varieties can be cultivated to limit production losses. At the same time, this would allow the crop planting area to be expanded, hence improving the economic benefits.MethodsIn this study, the transcriptome data of Yunwu Tribute Tea under cold conditions were obtained using the Illumina HiSeq platform. By analyzing changes in transcriptome data associated with the antioxidant enzyme system, plant hormone signal transduction, proline and tyrosine metabolism pathways, and transcription factors, the molecular mechanisms involved in Yunwu Tribute Tea under cold stress were investigated.ResultsIn this study, Illumina HiSeq technology was applied to investigate the cold-tolerance mechanism. For this purpose, cDNA libraries were obtained from two groups of samples, namely the cold-treated group (DW) and the control group (CK). A total of 185,973 unigenes were produced from 511,987 assembled transcripts; among these, 16,020 differentially expressed genes (DEGs) (corrected p-value < 0.01, |log2(fold change)| >3), including 9606 up-regulated and 6414 down-regulated genes, were obtained. Moreover, the antioxidant enzyme system, plant hormone signal transduction, proline and tyrosine metabolism pathways, and transcription factors were analyzed; based on these results, a series of candidate genes related to cold stress were screened out and discussed. The physiological indexes related to the low-temperature response were tested, along with five DEGs which were validated by quantitative real-time PCR.ConclusionsDifferential gene expression analysis has confirmed that substantial cold-responsive genes are related to the antioxidant enzyme system, plant hormone signal transduction, proline metabolism pathway, tyrosine metabolism pathway, and transcription factors.

Dataset Information

Stress Responses of Shade-Treated Tea Leaves to High Light Exposure after Removal of Shading.

Publications

Stress Responses of Shade-Treated Tea Leaves to High Light Exposure after Removal of Shading.

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