Transcriptome and Phytochemical Analyses Provide New Insights Into Long Non-Coding RNAs Modulating Characteristic Secondary Metabolites of Oolong Tea (Camellia sinensis) in Solar-Withering

Abstract

Oolong tea is a popular and semi-fermented beverage. During the processing of tea leaves, withering is the first indispensable process for improving flavor. However, the roles of long non-coding RNAs (lncRNAs) and the characteristic secondary metabolites during the withering of oolong tea leaves remain unknown. In this study, phytochemical analyses indicated that total polyphenols, flavonoids, catechins, epigallocatechin (EGC), catechin gallate (CG), gallocatechin gallate (GCG), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG) were all less abundant in the solar-withered leaves (SW) than in the fresh leaves (FL) and indoor-withered leaves (IW). In contrast, terpenoid, jasmonic acid (JA), and methyl jasmonate (MeJA) contents were higher in the SW than in the FL and IW. By analyzing the transcriptome data, we detected 32,036 lncRNAs. On the basis of the Kyoto Encyclopedia of Genes and Genomes analysis, the flavonoid metabolic pathway, the terpenoid metabolic pathway, and the JA/MeJA biosynthesis and signal transduction pathway were enriched pathways. Additionally, 63 differentially expressed lncRNAs (DE-lncRNAs) and 23 target genes were identified related to the three pathways. A comparison of the expression profiles of the DE-lncRNAs and their target genes between the SW and IW revealed four up-regulated genes (FLS, CCR, CAD, and HCT), seven up-regulated lncRNAs, four down-regulated genes (4CL, CHI, F3H, and F3'H), and three downregulated lncRNAs related to flavonoid metabolism; nine up-regulated genes (DXS, CMK, HDS, HDR, AACT, MVK, PMK, GGPPS, and TPS), three up-regulated lncRNAs, and six down-regulated lncRNAs related to terpenoid metabolism; as well as six upregulated genes (LOX, AOS, AOC, OPR, ACX, and MFP2), four up-regulated lncRNAs, and three down-regulated lncRNAs related to JA/MeJA biosynthesis and signal transduction. These results suggested that the expression of DE-lncRNAs and their targets involved in the three pathways may be related to the low abundance of the total polyphenols, flavonoids, and catechins (EGC, CG, GCG, ECG, and EGCG) and the

UV-B Induces Distinct Transcriptional Re-programing in UVR8-Signal Transduction, Flavonoid, and Terpenoids Pathways in Camellia sinensis

“…There was no significant change at 2 and 8 h treatment compared to control in most of the tested metabolites, suggesting that the initial exposure to UVB led to different display in gene expression in tea shoots. This observation are in line with those made by Hectors et al (2007) and Zhu et al (2019). Even though the mechanisms underlying such differential abundance alterations in the tested catechins need further investigation, this finding is largely consistent with a previous report that a low fluence range of UV-B radiation results in decrease in all tested catechins throughout all time intervals (0, 30, 60, and 360 min), except for a slight increase in total catechin abundance detected at the interval of 30 min only in the tea cultivars "Fudingdabai" and "Yulan" (Zheng et al, 2008).…”

Genome-Wide Investigation of N6-Methyladenosine Regulatory Genes and Their Roles in Tea (Camellia sinensis) Leaves During Withering Process

“…Flavonoids are characteristic metabolites associated with the bitterness and astringency of tea flavor, and their accumulation in tea plants has also been found to be regulated by AS events ( Zhu et al, 2018b ). Moreover, a previous study found that the flavonoid content in SW was significantly lower than that in FL and IW ( Zhu et al, 2019 ). Accordingly, we speculated that m6A regulatory genes may be implicated in flavonoid metabolism through AS regulatory mechanism, thereby affecting the formation of tea flavor during the withering process.…”

“…After 12- and 24-h incubations, the collected shoots were used for methylation level and qRT-PCR analyses. The flavonoid content of these shoots was also determined as described elsewhere ( Zhu et al, 2019 ). The specific siRNAs targeting m6A regulatory genes were synthesized from GenePharma (Shanghai, China).…”

Dynamic characteristics and functional analysis provide new insights into long non-coding RNA responsive to Verticillium dahliae infection in Gossypium hirsutum

“…Previous studies have showed that JA plays an important role in cotton resistance to V. dahliae [ 11 ]. Recently, 18 tea lncRNAs have been identified affecting JA biosynthesis through regulating the expression of JA-related genes [ 55 ]. Moreover, lncRNAs show low conservation among species [ 56 ].…”