The oil of Camellia spp. has become a well-known high-quality edible oil because of its rich nutrition. It is of great significance to breed fine varieties of Camellia spp. for the sustainable growth of the Camellia spp. industry. This study mainly evaluated the quality and antioxidant capacity of the camellia seed from several sources. The fatty acid composition and main active components of 40 kinds of C. oleifera, C. vietnamensis, C. osmantha, and C. gigantocarpa seeds, and so on, from different regions, were tested using GC–MS and HPLC. The quality of different Camellia spp. germplasm resources was comprehensively evaluated using multiple indices. The unsaturated fatty acid content and the antioxidant capacity of C. vietnamensis from Hainan were higher than those of C. oleifera Abel. In addition, there were a few differences in the fatty acid compositions of Camellia spp. oil from different species. Correlation analysis confirmed that rutin, total saponin, total flavonoids, squalene, and vitamin E were strongly correlated to the antioxidant capacity of Camellia spp. In the comprehensive evaluation, the best quality and strongest antioxidant activity were found for Chengmai Dafeng (C. vietnamensis). These methods in the study were applied for the first time for the quality evaluation of the Camellia spp. species. This study provided new insights into the quality evaluation of the Camellia spp. species, thus facilitating further development of variety breeding along with quality evaluation.

Flavonoids are secondary metabolites widely found in plants, which perform various biological activities, such as antiinflammation, antioxidation, antitumor, and so on. Camellia vietnamensis Huang, a species of oil-tea Camellia tree, is an important woody oil crop species widely planted on Hainan Island, which provides health benefits with its high antioxidant activity and abundant flavonoid content. However, very little is known about the overall molecular mechanism of flavonoid biosynthesis in C. vietnamensis Huang. In this study, methyl jasmonate (MeJA) is used as an inducer to change the content of secondary metabolites in C. vietnamensis. Then, the potential mechanisms of flavonoid biosynthesis in C. vietnamensis leaves in response to MeJA were analyzed by metabolomics and transcriptomics (RNA sequencing). The results showed that metabolome analysis detected 104 flavonoids and 74 fatty acyls which showed different expression patterns (increased or decreased expression). It was discovered by KEGG analysis that three differentially accumulated metabolites (cinnamaldehyde, kaempferol and quercitrin) were annotated in the phenylpropanoid biosynthesis (ko00940), flavonoid biosynthesis (ko00941), and flavone and flavonol biosynthesis (ko00944) pathways. In the transcriptome analysis, 35 different genes involved in the synthesis of flavonoids were identified by MapMan analysis. The key genes (PAL, 4CL, CCR, CHI, CHS, C4H, FLS) that might be involved in the formation of flavonoid were highly expressed after 2 h of MeJA treatment. This study provides new insights and data supporting the molecular mechanism underlying the metabolism and synthesis of flavonoids in C. vietnamensis under MeJA treatment.

We conducted a study to examine the growth and physiological changes in 12 different ecotypes of Sesuvium portulacastrum collected from Hainan Island in China. These ecotypes were subjected to different concentrations (0, 200, 400, and 600 mmol/L) of sodium chloride (NaCl) salt stress for 14 days. We also analyzed the expression of metabolic genes related to stress response. Under low salt stress, indicators such as plant height in region K (0 mmol/L: 45% and highest at 200 mmol/L: 80%), internode length (0 mmol/L: 0.38, 200 mmol/L: 0.87, 400 mmol/L: 0.25, and 600 mmol/L: 1.35), as well as leaf area, relative water content, fresh weight, and dry weight exhibited an overall increasing trend with the increase in salt concentration. However, as the salt concentration increased, these indicators showed a decreasing trend. Proline and malondialdehyde contents increased with higher salt concentrations. When the NaCl concentration was 400 mmol/L, MDA content in the leaves was highest in the regions E (196.23%), F (94.28%), J (170.10%), and K (136.08%) as compared to the control group, respectively. Most materials demonstrated a significant decrease in chlorophyll a, chlorophyll b, and total chlorophyll content compared to the control group. Furthermore, the ratio of chlorophyll a to chlorophyll b (Rab) varied among different materials. Using principal component analysis, we identified three ecotypes (L from Xinglong Village, Danzhou City; B from Shuigoupo Village, Lingshui County; and J from Haidongfang Park, Dongfang City) that represented high, medium, and low salt tolerance levels, respectively, based on the above growth and physiological indexes. To further investigate the expression changes of related genes at the transcriptional level, we employed qRT-PCR. The results showed that the relative expression of SpP5CS1, SpLOX1, and SpLOX1 genes increased with higher salt concentrations, which corresponded to the accumulation of proline and malondialdehyde content, respectively. However, the relative expression of SpCHL1a and SpCHL1b did not exhibit a consistent pattern. This study contributes to our understanding of the salt tolerance mechanism in the true halophyte S. portulacastrum, providing a solid theoretical foundation for further research in this field.

Oil-tea camellia trees, the collective term for a class of economically valuable woody oil crops in China, have attracted extensive attention because of their rich nutritional and pharmaceutical value. This study aimed to analyze the genetic relationship and genetic diversity of oil-tea camellia species using polymorphic SSR markers. One-hundred and forty samples of five species were tested for genetic diversity using twenty-four SSR markers. In this study, a total of 385 alleles were identified using 24 SSR markers, and the average number of alleles per locus was 16.0417. The average Shannon’s information index (I) was 0.1890, and the percentages of polymorphic loci (P) of oil-tea camellia trees were 7.79−79.48%, indicating that oil-tea camellia trees have low diversity. Analysis of molecular variance (AMOVA) showed that the majority of genetic variation (77%) was within populations, and a small fraction (23%) occurred among populations. Principal coordinate analysis (PCoA) results indicated that the first two principal axes explained 7.30% (PC1) and 6.68% (PC2) of the total variance, respectively. Both UPGMA and PCoA divided the 140 accessions into three groups. Camellia oleifera clustered into one class, Camellia vietnamensis and Camellia gauchowensis clustered into one class, and Camellia crapnelliana and Camellia chekiangoleosa clustered into another class. It could be speculated that the genetic relationship of C. vietnamensis and C. gauchowensis is quite close. SSR markers could reflect the genetic relationship among oil-tea camellia germplasm resources, and the results of this study could provide comprehensive information on the conservation, collection, and breeding of oil-tea camellia germplasms.

Butylparaben (BuP), as an emerging contaminant with endocrine-disrupting effects, may exert effects on skin pigmentation in fish by interfering with the neuroendocrine system. Therefore, models of BuP exposure in Nile tilapia (Oreochromis niloticus) were established by adding different doses of BuP (0, 5, 50, 500, and 5000 ng/L) for 56 days. The obtained results showed that BuP exposure induced darker skin pigmentation, manifested as increased melanin content of skin, while genes related to melanin synthesis, including α-MSH and Asip2, significantly changed. In addition, BuP exposure reduced dopamine and γ-aminobutyric acid content in the brain, which is related to the synthesis of α-MSH. Furthermore, the release of neurotransmitters from the brain is affected by light. Thus, the relative gene expression levels in the phototransduction pathway were evaluated to explore the molecular mechanism of BuP-induced darker skin pigmentation, and the obtained results showed that Arr3a and Arr3b expression was significantly upregulated, whereas Opsin expression was significantly downregulated in a BuP dose-dependent manner, indicating that BuP inhibited phototransduction from the retina to the brain. Importantly, correlation analysis results showed that all melanin indexes were significantly positively correlated with Arr3b expression and negatively correlated with Opsin expression. This study indicated that BuP induced darker skin pigmentation in Nile tilapia via the neuroendocrine circuit, which reveals the underlying molecular mechanism for the effects of contaminants in aquatic environments on skin pigmentation in fish.

Dendropanax oligodontus, which belongs to the family Araliaceae, is an endemic and endangered species of Hainan Island, China. It has potential economic and medicinal value owing to the presence of phenylpropanoids, flavonoids, triterpenoids, etc. The analysis of the structure and characteristics of the D. oligodontus chloroplast genome (cpDNA) is crucial for understanding the genetic and phylogenetic evolution of this species. In this study, the cpDNA of D. oligodontus was sequenced for the first time using next-generation sequencing methods, assembled, and annotated. We observed a circular quadripartite structure comprising a large single-copy region (86,440 bp), a small single-copy region (18,075 bp), and a pair of inverted repeat regions (25,944 bp). The total length of the cpDNA was 156,403 bp, and the GC% was 37.99%. We found that the D. oligodontus chloroplast genome comprised 131 genes, with 86 protein-coding genes, 8 rRNA genes, and 37 tRNAs. Furthermore, we identified 26,514 codons, 13 repetitive sequences, and 43 simple sequence repeat sites in the D. oligodontus cpDNA. The most common amino acid encoded was leucine, with a strong A/T preference at the third position of the codon. The prediction of RNA editing sites in the protein-coding genes indicated that RNA editing was observed in 19 genes with a total of 54 editing sites, all of which involved C-to-T transitions. Finally, the cpDNA of 11 species of the family Araliaceae were selected for comparative analysis. The sequences of the untranslated regions and coding regions among 11 species were highly conserved, and minor differences were observed in the length of the inverted repeat regions; therefore, the cpDNAs were relatively stable and consistent among these 11 species. The variable hotspots in the genome included clpP, ycf1, rnK-rps16, rps16-trnQ, atpH-atpI, trnE-trnT, psbM-trnD, ycf3-trnS, and rpl32-trnL, providing valuable molecular markers for species authentication and regions for inferring phylogenetic relationships among them, as well as for evolutionary studies. Evolutionary selection pressure analysis indicated that the atpF gene was strongly subjected to positive environmental selection. Phylogenetic analysis indicated that D. oligodontus and Dendropanax dentiger were the most closely related species within the genus, and D. oligodontus was closely related to the genera Kalopanax and Metapanax in the Araliaceae family. Overall, the cp genomes reported in this study will provide resources for studying the genetic diversity and conservation of the endangered plant D. oligodontus, as well as resolving phylogenetic relationships within the family.