Integrated metabolome, full-length sequencing, and transcriptome analyses unveil the molecular mechanisms of color formation of the canary yellow and red bracts of Bougainvillea × buttiana 'Chitra'.

Bougainvillea is a typical tropical flower of great ornamental value due to its colorful bracts. The molecular mechanism behind color formation is not well-understood. Therefore, this research conducted metabolome analysis, transcriptome analysis, and multi-flux full-length sequencing in two color bracts of Bougainvillea × buttiana 'Chitra' to investigate the significantly different metabolites (SDMs) and differentially expressed genes (DEGs). Overall, 261 SDMs, including 62 flavonoids and 26 alkaloids, were detected, and flavonols and betalains were significantly differentially accumulated among the two bracts. Furthermore, the complete-length transcriptome of Bougainvillea × buttiana was also developed, which contained 512 493 non-redundant isoforms. Among them, 341 210 (66.58%) displayed multiple annotations in the KOG, GO, NR, KEGG, Pfam, Swissprot, and NT databases. RNA-seq findings revealed that 3610 DEGs were identified between two bracts. Co-expression analysis demonstrated that the DEGs and SDMs involved in flavonol metabolism (such as CHS, CHI, F3H, FLS, CYP75B1, kaempferol, and quercetin) and betacyanin metabolism (DODA, betanidin, and betacyanins) were the main contributors for the canary yellow and red bract formation, respectively. Further investigation revealed that several putative transcription factors (TFs) might interact with the promoters of the genes mentioned above. The expression profiles of the putative TFs displayed that they may positively and negatively regulate the structural genes' expression profiles. The data revealed a potential regulatory network between important genes, putative TFs, and metabolites in the flavonol and betacyanin biosynthesis of Bougainvillea × buttiana 'Chitra' bracts. These findings will serve as a rich genetic resource for future studies that could create new color bracts.

Integrated metabolome, transcriptome analysis, and multi-flux full-length sequencing offer novel insights into the function of lignin biosynthesis as a Sesuvium portulacastrum response to salt stress.

Sesuvium portulacastrum is a typical halophyte. However, few studies have investigated its salt-tolerant molecular mechanism. In this study, metabolome, transcriptome, and multi-flux full-length sequencing analysis were conducted to investigate the significantly different metabolites (SDMs) and differentially expressed genes (DEGs) of S. portulacastrum samples under salinity. The complete-length transcriptome of S. portulacastrum was developed, which contained 39,659 non-redundant unigenes. RNA-seq results showed that 52 DEGs involved in lignin biosynthesis may be responsible for S. portulacastrum salt tolerance. Furthermore, 130 SDMs were identified, and the salt response could be attributed to the p-coumaryl alcohol-rich in lignin biosynthesis. The co-expression network that was constructed after comparing the different salt treatment processes showed that the p-Coumaryl alcohol was linked to 30 DEGs. Herein, 8 structures genes, i.e., Sp4CL, SpCAD, SpCCR, SpCOMT, SpF5H, SpCYP73A, SpCCoAOMT, and SpC3'H were identified as significant factors in regulating lignin biosynthesis. Further investigation revealed that 64 putative transcription factors (TFs) may interact with the promoters of the above-mentioned genes. Together, the data revealed a potential regulatory network comprising important genes, putative TFs, and metabolites involved in the lignin biosynthesis of S. portulacastrum roots under salt stress, which could serve as a rich useful genetic resource for breeding excellent salt-tolerant plants.

The mechanism leading to color differences between purple-red and green partridge tea leaves.

BACKGROUND: Partridge tea (Mallotus oblongifolius) is used as an important beverage and medical plant in Hainan province of China. Although some information about the morphology, cytology, and genetics of partridge tea has been reported in the literature, knowledge about this plant is still very limited. The leaves are the most important part for every tea plant, with a major role in nutrition and other functions. The leaves of different cultivars of partridge tea are different in colors and functions. The molecular mechanism of color formation of partridge tea leaf is still unclear. We reveal the molecular mechanism of the color difference between purple-red and green partridge tea leaves through metabolome and transcriptome analysis. RESULTS: We identified 665 compounds in the two partridge tea cultivars through metabolome analysis. Among these compounds, the content of 324 differed between the two cultivars. We also annotated 50 042 unigenes in the two cultivars by transcriptome analysis; 9665 unigenes were expressed differently between the two cultivars. Using an integrated analysis of the metabolome and transcriptome data, we found that the compounds and genes involved in anthocyanin biosynthesis were up-regulated in the purple-red leaves, compared with the green leaves. CONCLUSION: Our results showed that the anthocyanin biosynthesis pathway genes were up-regulated, which resulted in the up-regulation of the anthocyanin, making the leaf color purple-red. Our study reveals the molecular mechanism of the color difference between purple-red and green partridge tea, and lays a foundation for the genetic breeding of partridge tea genetic and the utilization of its volatile components. © 2022 Society of Chemical Industry.

Dietary supplementation with a microencapsulated complex of thymol, carvacrol, and cinnamaldehyde improves intestinal barrier function in weaning piglets.

BACKGROUND: The authors previously prepared a microencapsulated complex of thymol, carvacrol, and cinnamaldehyde (MEEO). This study aimed to evaluate the effect of MEEO on the intestinal mucosal barrier and homeostasis in weaning piglets. A comparison of the effect of MEEO versus chlortetracycline (CTC) was performed in this study. RESULTS: Piglets were divided into three groups - control (Con), MEEO, and CTC groups - and raised for 28 days. The results showed that MEEO significantly elevated the ratio of the villus height and the crypt depth in the jejunum and decreased the crypt depth in the ileum compared with the other groups (P < 0.05); it also upregulated the messenger ribonucleic acid (mRNA) expression of tight junction protein in the small intestine. Compared with the Con group, MEEO increased the concentration of secretory immunoglobulin A (sIgA), cathelicidin antimicrobial peptides (CAMP), and interleukin 10 (IL-10), while decreasing the interleukin 1 beta (IL-1ß) concentration in both jejunal and ileal mucosa (P < 0.05). The mRNA expression of jejunal mucosal MUC1 and ileal mucosal MUC2 was increased in the MEEO group compared with the other groups (P < 0.05). Intestinal microbial analysis showed that dietary treatment had little impact on the ileal microbial structure. A significant rise in the genus Lactobacillus was, however, found in the MEEO group. There is a positive correlation between the Lactobacillus and sIgA, and between the Lactobacillus and CAMP, indicating that an improvement in the mucosal barrier function by the addition of MEEO may be associated with the proliferation of Lactobacillus. CONCLUSION: Dietary supplementation with MEEO improves intestinal barrier function in weaning piglets, the effect of which was superior to CTC. © 2022 Society of Chemical Industry.

Combined physiological and transcriptome analysis revealed the response mechanism of Pogostemon cablin roots to p-hydroxybenzoic acid.

Pogostemon cablin (patchouli) cultivation is challenged by serious soil sickness, of which autotoxins accumulation is a major cause. p-hydroxybenzoic acid (p-HBA) is one of the main autotoxins of patchouli. However, the molecular mechanism underlying the response of patchouli to p-HBA remains unclear. In this study, RNA-sequencing combined with physiological analysis was used to monitor the dynamic transcriptomic and physiological changes in patchouli seedlings 0, 6, 12, 24, 48, and 96 h after p-HBA treatment. p-HBA stress inhibited root biomass accumulation, induced excessive hydrogen peroxide accumulation and lipid peroxidation, and activated most antioxidant enzymes. Compared with that of the control, the osmotic adjustment substance content was elevated with treatment. Subsequently, 15,532, 8,217, 8,946, 2,489, and 5,843 differentially expressed genes (DEGs) at 6, 12, 24, 48, and 96 h after p-HBA treatment, respectively, were identified in patchouli roots. GO functional enrichment analysis showed that the DEGs were enriched mainly in plasma membrane, defense response, response to chitin, DNA-binding transcription factor activity and abscisic acid-activated signaling pathway. The upregulated genes were involved in glycolysis/gluconeogenesis, cysteine and methionine metabolism, starch and sucrose metabolism, biosynthesis of unsaturated fatty acids, and linoleic acid metabolism. Genes associated with MAPK signaling pathway-plant, plant-pathogen interaction, plant hormone signal transduction were downregulated with p-HBA treatment. These pathways are related to root browning and rotting, leading to plant death.

Identification and Expression Analysis of WRKY Gene Family in Response to Abiotic Stress in Dendrobium catenatum.

Dendrobium catenatum has become a rare and endangered medicinal plant due to habitat loss in China. As one of the most important and largest transcription factors, WRKY plays a critical role in response to abiotic stresses in plants. However, little is known regarding the functions of the WRKY family in D. catenatum. In this study, a total of 62 WRKY genes were identified from the D. catenatum genome. Phylogenetic analysis revealed that DcWRKY proteins could be divided into three groups, a division supported by the conserved motif compositions and intron/exon structures. DcWRKY gene expression and specific responses under drought, heat, cold and salt stresses were analyzed through RNA-seq data and RT-qPCR assay. The results showed that these genes had tissue-specificity and displayed different expression patterns in response to abiotic stresses. The expression levels of DcWRKY22, DcWRKY36 and DcWRKY45 were up-regulated by drought stress. Meanwhile, DcWRKY22 was highly induced by heat in roots, and DcWRKY45 was significantly induced by cold stress in leaves. Furthermore, DcWRKY27 in roots and DcWRKY58 in leaves were extremely induced under salt treatment. Finally, we found that all the five genes may function in ABA- and SA-dependent manners. This study identified candidate WRKY genes with possible roles in abiotic stress and these findings not only contribute to our understanding of WRKY family genes, but also provide valuable information for stress resistance development in D. catenatum.

Ultrasound-Enhanced Subcritical Fluid Extraction of Essential Oil from Nymphaea alba var and Its Antioxidant Activity.

Background: The essential oil content of the water lily is extremely low; thus, finding a new method that can extract essential oil from water lilies with a high extraction rate and no residual organic solvents is essential. Objective: The optimal processing conditions for the ultrasound-enhanced subcritical fluid extraction of essential oil from Nymphaea alba var (red water lily) and the antioxidant activity of the essential oil in vitro are investigated to provide theoretical bases for identification and development. Methods: Single-factor experiments and orthogonal designs are performed to determine the effects of extraction conditions on essential oil yields. The chemical composition of essential oil is analyzed using GC-MS. Results: The optimum extraction parameters are established as follows: extraction temperature, 35°C; extraction time, 30 min/time for four times; ratio of material to liquid, 1:3; ultrasound power, 250 W/L; and ultrasonic frequency, 20 kHz. The extraction rate of essential oil is 0.315% under these conditions. Eleven components comprise more than 1% content. The main chemical constituents are 8-hexadecyne (31.04%) and 2,6,10-trimethyl-tetradecane (3.95%). The essential oil from N. alba var has an antioxidant activity in vitro; however, its antioxidant activity is weaker than that of butylated hydroxytoluene. Conclusions: Subcritical fluid is suitable for the extraction of essential oil from N. alba var, and the essential oil has a good antioxidant activity. Highlights: The essential oil content of N. alba var is 0.315%. Forty-seven chemical constituents are identified and isolated from N. alba var and analyzed by GC-MS.

Physiological and transcriptomic analysis revealed the involvement of crucial factors in heat stress response of Rhododendron hainanense.

Molecular regulatory mechanism of heat stress response (HSR) in Ericaceae remains unknown. Here, we sought to identify HSR mechanisms in Rhododendron hainanense, a Ericaceae species, through a combination of physiological and transcriptomic studies. The levels of MDA, H2O2, Pro, SOD, CAT and APX in leaves of R. hainanense were analyzed to characterize a dramatic difference in varied temperature treatment. Also, three sequencing libraries, including one control and two heat stress (HS)-treated samples, were constructed for comparative transcriptomic analysis. By Illumina sequencing and Trinity strategy, 350 million clean reads (average length = 149 bp) was assembled into 183,486 unigenes. According to analysis of differential expression genes (DEGs), a total of 2658 DEGs were obtained. Moreover, a complex interaction network of 982 DEGs was established, of which master portions were comprised of 109 transcription factors (TFs). Importantly, integrated differential expression profiling, qRT-PCR and functional analysis, several TFs of R. hainanense (ABR1, IAA26, OBF1, LUX, SCL3, DIV, NAC29, NAC72 and TCP3) and their potential regulations for the crosstalk between hormonal signal and HSR were identified. These findings will contribute to our understanding of the regulatory mechanisms of HSR in R. hainanense, breeding cultivars with improved thermotolerance.

Influence of host tree species on isolation and communities of mycorrhizal and endophytic fungi from roots of a tropical epiphytic orchid, Dendrobium sinense (Orchidaceae).

Most studies on the host preference of orchids have focused on the association between orchids and host characteristics, but little is known about the differences of mycorrhizal and endophytic fungal communities in epiphytic orchids growing on different host tree species. We selected Dendrobium sinense, a tropical epiphytic orchid, to determine if fungal endophytes from the roots of D. sinense were preferentially correlated with host tree species. Fifty-six fungal operational taxonomic units (OTUs) from 36 host trees were identified. The results indicated that the species richness and diversity of mycorrhizal and endophytic fungal communities isolated from D. sinense roots were strongly influenced by host tree species. Both species richness and diversity indices showed that D. sinense roots on Syzygium buxifolium harbored the most diverse and abundant endophytic fungi. Species of Tulasnellaceae were dominant on S. buxifolium and Rhododendron moulmainense but infrequent on Cyclobalanopsis disciformis and Podocarpus neriifolius. Our results provide evidence for distinct mycorrhizal and endophytic fungal communities on different host tree species. Further research focusing on fungi-orchid-host preference could be conducted to increase our understanding for the in situ conservation of epiphytic orchids.

Immunogenicity of C-terminus of Plasmodium falciparum merozoite surface protein 1 expressed as a non-glycosylated polypeptide in yeast.

The C-terminal region of the merozoite surface protein 1 (MSP119) is one of the most promising vaccine candidates against the erythrocytic forms of malaria. In the present study, a gene encoding Plasmodium falciparum MSP119 was expressed in yeast Pichia pastoris. A non-glycosylated form of the recombinant protein MSP119 was purified from culture medium. This recombinant protein maintains its antigenicity. Significant immune responses were seen in C57BL/6 mice after the second immunization. Moreover, the specific antibodies recognized the native antigens of P. falciparum. The prevailing isotypes of immunoglobulin (Ig) G associated with immunization were IgG1, IgG2a and IgG2b. The antibodies isolated from mouse sera immunized with MSP119 can inhibit parasite growth in vitro. Based on these immunological studies, we concluded that MSP119 deserves further evaluation in pre-clinical immunizations against P. falciparum.