Camellia oleifera (C. oleifera) is one of the four major woody oil-bearing crops in the world and has relatively high ecological, economic, and medicinal value. Its seeds undergo a series of complex physiological and biochemical changes during ripening, which is mainly manifested as the accumulation and transformation of certain metabolites closely related to oil quality, especially flavonoids and fatty acids. To obtain new insights into the underlying molecular mechanisms, a parallel analysis of the transcriptome and proteome profiles of C. oleifera seeds at different maturity levels was conducted using RNA sequencing (RNA-seq) and isobaric tags for relative and absolute quantification (iTRAQ) complemented with gas chromatography-mass spectrometry (GC-MS) data. A total of 16,530 transcripts and 1228 proteins were recognized with significant differential abundances in pairwise comparisons of samples at various developmental stages. Among these, 317 were coexpressed with a poor correlation, and most were involved in metabolic processes, including fatty acid metabolism, α-linolenic acid metabolism, and glutathione metabolism. In addition, the content of total flavonoids decreased gradually with seed maturity, and the levels of fatty acids generally peaked at the fat accumulation stage; these results basically agreed with the regulation patterns of genes or proteins in the corresponding pathways. The expression levels of proteins annotated as upstream candidates of phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS) as well as their cognate transcripts were positively correlated with the variation in the flavonoid content, while shikimate O-hydroxycinnamoyltransferase (HCT)-encoding genes had the opposite pattern. The increase in the abundance of proteins and mRNAs corresponding to alcohol dehydrogenase (ADH) was associated with a reduction in linoleic acid synthesis. Using weighted gene coexpression network analysis (WGCNA), we further identified six unique modules related to flavonoid, oil, and fatty acid anabolism that contained hub genes or proteins similar to transcription factors (TFs), such as MADS intervening keratin-like and C-terminal (MIKC_MADS), type-B authentic response regulator (ARR-B), and basic helix-loop-helix (bHLH). Finally, based on the known metabolic pathways and WGCNA combined with the correlation analysis, five coexpressed transcripts and proteins composed of cinnamyl-alcohol dehydrogenases (CADs), caffeic acid 3-O-methyltransferase (COMT), flavonol synthase (FLS), and 4-coumarate: CoA ligase (4CL) were screened out. With this exploratory multiomics dataset, our results presented a dynamic picture regarding the maturation process of C. oleifera seeds on Hainan Island, not only revealing the temporal specific expression of key candidate genes and proteins but also providing a scientific basis for the genetic improvement of this tree species.

Background Mallotus oblongifolius, an evergreen shrub endemic to Hainan Island, China, is important both medicinally and economically. Due to its special medicinal significance and the continuing rise of market demand, its populations in the wild have been subject to long-term illegal and unrestrained collection. Hence, an evaluation of genetic variability is essential for the conservation and genetic reserve development of this species. Methods Sequence-related amplified polymorphism (SRAP) and inter-simple sequence repeat (ISSR) markers were employed to assess the genetic diversity and genetic structure of 20 natural populations of M. oblongifolius growing in different eco-geographical regions of Hainan Island, China. Results We revealed a considerable genetic diversity (h = 0.336, I = 0.5057, SRAP markers; h = 0.3068, I = 0.4657, ISSR markers) and weak genetic differentiation (Gst = 0.2764 for SRAP, Gst = 0.2709 for ISSR) with the same gene flow (Nm = 1.3092 for SRAP, Nm = 1.346 for ISSR) among the M. oblongifolius populations. The Mantel Test showed that the distribution of genetic variation among populations could not be explained by the pronounced geographical distances (r = 0.01255, p = 0.5538). All results of the Unweighted Pair Group Method with Arithmetic Mean (UPGMA), Neighbor-joining (NJ), Principal Coordinate Analysis (PCoA) and Bayesian analyses supported a habitat-specific genetic clustering model for M. oblongifolius, indicating a local adaptive divergence for the studied populations. Discussion We suggested that the habitat fragmentation and specificity for M. oblongifolius populations weakened the natural gene flow and promoted an adaptation to special habitats, which was the main reason for local adaptive divergence among M. oblongifolius.

Camellia oleifera Abel. (C. oleifera), as an important woody tree species producing edible oils in China, has attracted enormous attention due to its abundant unsaturated fatty acids and their associated benefits to human health. To reveal novel insights into the characters during the maturation period of this plant as well as the molecular basis of fatty acid biosynthesis and degradation, we conducted a conjoint analysis of the transcriptome and proteome of C. oleifera seeds from Hainan Island. Using RNA sequencing (RNA-seq) technology and shotgun proteomic method, 59,391 transcripts and 40,500 unigenes were obtained by TIGR Gene Indices Clustering Tools (TGICL), while 1691 protein species were identified from Mass Spectrometry (MS). Subsequently, all genes and proteins were employed in euKaryotic Orthologous Groups (KOG) classification, Gene Ontology (GO) annotation, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis to investigate their essential functions. The results indicated that the most abundant pathways were biological metabolic processes. There were 946 unigenes associated with lipid metabolism at the transcriptome level, with 116 proteins at the proteome level; among these, 38 specific proteins were involved in protein-protein interactions, with the majority being related to fatty acid catabolic process. The expression levels of 21 candidate unigenes encoding target proteins were further detected by quantitative real-time polymerase chain reaction (qRT-PCR). Finally, Gas Chromatography Mass Spectrometry (GC-MS) was carried out to determine the fatty acid composition of C. oleifera oil. These findings not only deepened our understanding about the molecular mechanisms of fatty acid metabolism but also offered new evidence concerning the roles of relevant proteins in oilbearing crops. Furthermore, the lipid-associated proteins recognized in this research might be helpful in providing a reference for the synthetic regulation of C. oleifera oil quality by genetic engineering techniques, thus resulting in potential application in agriculture.

Liver damage seriously affects human health. Over 35% of cases of acute liver damage are caused by alcohol damage. Thus, finding drugs that can inhibit and effectively treat this disease is necessary. This article mainly focuses on the effect of the metabolome physical activity of active peptides in Camellia vietnamensis active peptide (CMAP) and improving liver protection. DEAE Sepharose FF ion-exchange column chromatography was used in separating and purifying crude peptides from Camellia vietnamensis Two components, A1 and A2, were obtained, and the most active A1 was selected. Sephadex G-100 gel column chromatography was used in A1 separation and purification. Three components, Al-1, Al-2, and Al-3, were obtained. Through antioxidant activity in vitro as an index of inspection, the relatively active component A1-2 was removed. Reverse-phase high-performance liquid chromatography showed that the purity of component A1-2 was 93.45%. The extracted CMAPs acted on alcoholic liver injury cells. Metabolomics studies revealed that the up-regulated metabolites were ribothymidine and xanthine; the down-regulated metabolites were hydroxyphenyllactic acid, creatinine, stearoylcarnitine, and inosine. This study provides an effective theoretical support for subsequent research.

Drought stress is considered the main obstacle restricting Camellia vietnamensis Huang (C. vietnamensis) yield. Hainan is the southernmost distribution region of C. vietnamensis in China and experiences a drought period annually. To study the drought-stress-response mechanism of C. vietnamensis, we treated seedlings of drought-tolerant (HD1) and drought-sensitive (WH1) cultivars with PEG-6000 (PEG) to simulate drought stress and compared the physiology and transcriptome of their leaves at 0 d, 3 d and 6 d posttreatment. Under drought stress, the growth of C. vietnamensis was inhibited, the relative water content (RWC) of leaves decreased and the contents of malondialdehyde (MDA), antioxidant enzyme activities, osmotic regulatory substances and secondary metabolites increased. Compared with those of WH1, the leaf RWC, osmotic-regulation substance content (proline, soluble protein and soluble sugar) and antioxidant enzyme activity (superoxide dismutase, peroxidase and catalase) of HD1 were significantly increased, while the relative electrical conductivity and MDA content were significantly decreased. Compared with WH1, 2812, 2070 and 919, differentially expressed genes (DEGs) were detected in HD1 0 d, 3 d and 6 d posttreatment, respectively, and the number of DEGs increased with increasing treatment time. The detected DEGs are involved in the drought stress response of C. vietnamensis mainly through plant-hormone signal transduction and lignin and flavonoid biosynthesis pathways. Drought stress significantly activated the expression of several lignin and flavonoid biosynthesis genes in HD1. Moreover, total flavonoid and total polyphenol contents in HD1 were significantly increased, suggesting that the accumulation of flavonoids may be a key factor in the drought stress response of C. vietnamensis. Additionally, 191 DEGs were associated with coding transcription factors (TFs). This study provides insight into the molecular mechanism of the drought stress response of C. vietnamensis and provides a theoretical basis for the development and cultivation of new drought-resistant cultivars.