Search

Abstract Background The extract from Metasequoia glyptostroboides Hu et Cheng, a rare and endangered species native to China, exhibits numerous biological and pharmacological activities. The species is recalcitrant to rooting during micropropagation, a challenge that has yet to be resolved. In this study, transcriptomic and hormonal analyses were conducted to appreciate the molecular mechanism of adventitious root (AR) formation in optimized rooting conditions. Results The use of 2/5-strength Woody Plant Medium (WPM) significantly promoted AR formation of M. glyptostroboides shoots while the content of endogenous auxin, cytokinins and gibberellins (GAs) varied at different stages of AR formation. Transcriptomic analysis showed the significant up- or down-regulation of differentially expressed genes (DEGs) associated with plant hormone signal transduction and the phenylpropanoid biosynthesis pathway in response to 2/5-strength WPM. DEGs related to the biosynthesis of indole-3-acetic acid, cytokinins and GAs were identified. Transcript factors involved in 13 families were also revealed. A weighted gene co-expression network analysis indicated a strong correlation between hormones and genes involved in plant hormone signal transduction and the phenylpropanoid biosynthetic pathway. Conclusions These results indicate that the AR-promoting potential of 2/5-strength WPM in M. glyptostroboides was due to complex interactions between hormones and the expression of genes related to plant hormone signal transduction and the phenylpropanoid biosynthetic pathway.

Euryodendron excelsum H. T. Chang, a rare and endangered evergreen tree that is endemic to China. The micropropagation system of this species has been established, but some challenges associated with in vitro rooting remained to be improved. In this study, the in vitro rooting of E. excelsum plantlets were optimized by dark exposure, and the network of gene expression and endogenous hormones levels during dark-induced adventitious root (AR) formation were revealed. AR formation of E. excelsum plantlets were significantly promoted by dark exposure, especially by dark exposure for 15 d. In the stems of E. excelsum plantlets under the treatment of dark exposure for 15 d, lower level of abscisic acid (ABA), gibberellic acid 1 (GA1), isopentenyladenine (IP), isopentenyladenosine (IPA) and zeatin (ZT), as well as higher level of GA7, jasmonic acid (JA) and salicylic acid (SA), promoted the whole course of AR formation. The higher level of trans-zeatin riboside (TZR) and T-zeatin (TZT) promoted the elongation of dark-induced AR, while higher level of indole-3-acetic acid (IAA) stimulated the process of AR primordia formation. Differentially expressed genes (DEGs) involved in hormone biosynthesis, plant hormone signal transduction and phenylpropanoid biosynthesis participated in the regulation of dark-induced AR development. The weighted gene co-expression network (WGCNA) analysis identified five modules that had highly correlation with phytohormone contents, and numerous hub genes associated with carotenoid biosynthesis, tryptophan metabolism, zeatin biosynthesis, alpha-Linolenic acid metabolism, phenylalanine metabolism, plant hormone signal transduction and phenylpropanoid biosynthesis were revealed. Those result will provide technical reference for in vitro rooting of woody species, and promote biological conservation and genetic engineering of rare and endangered species.

Soil salinity, a major environmental stress, restricts agricultural production worldwide. Gynura divaricata (L.) DC. is widely cultivated on tropical islands in China and has both edible and medicinal value. NaCl stress and growth indicators, antioxidant enzyme activity, as well as MDA, proline, and soluble sugar content, were determined. Based on the transcriptomic data of tissue-cultured G. divaricata plantlets grown in control (0 mM NaCl) and salt stress (50 and 200 mM NaCl) conditions, gene expression patterns were examined. KEGG enrichment analysis of differentially expressed genes indicated significant enrichment of plant hormone signaling, MAPK signaling, and starch and sucrose metabolism pathways. These findings allowed key biological pathways and salt stress-responsive genes to be identified, thus providing a molecular basis for breeding salt-tolerant G. divaricata varieties. This transcriptomic analysis revealed a complex tolerance mechanism of G. divaricata in response to NaCl, laying a foundation for screening and cloning key genes related to NaCl tolerance and studying their interactions. These findings would allow the molecular basis of NaCl tolerance to be explored, with the aim of breeding NaCl-tolerant varieties.

Hippeastrum, a highly diverse genus in the Amaryllidaceae family, is a valuable ornamental bulbous flowering plant. Somatic embryogenesis (SE) is an efficient method for mass production of Hippeastrum plantlets. Previous studies have been devoted to the in vitro propagation of Hippeastrum, but the SE and its regulatory networks are rarely reported. In this study, we established a direct SE method of Hippeastrum ‘Bangkok Rose’ using leaf bases as explants. MS supplemented with 1.00 mg · L−1 NAA +1.00 mg · L−1 KT + 0.25 mg · L−1 TDZ was the optimal medium for SE. Histological observations showed that the bipolar somatic embryo originated from the epidermal cell layer and underwent initiation, globular, scutellar and coleoptile stages. During SE, endogenous hormones of IAA, CTK, ABA, and SA were highly accumulated. Transcriptomic analysis revealed the genes encoding auxin biosynthesis/metabolic enzymes and efflux carriers were induced, while the auxin receptor of TIR1 and ARF transcriptional repressor of Aux/IAA were down-regulated and up-regulated, respectively, leading to suppression of auxin signaling. In contrast, cytokine signaling was promoted at the early stage of SE, as biosynthesis, transport, and signaling components were up-regulated. Various stress-related genes were up-regulated at the early or late stages of SE. Chromatin remodeling could also be dynamically regulated via distinct expression enzymes that control histone methylation and acetylation during SE. Moreover, key SE regulators, including WOXs and SERKs were highly expressed along with SE. Overall, the present study provides insights into the SE regulatory mechanisms of the Hippeastrum.

Objective: When chatting, people often forget what they want to say, that is, they suffer from subjective memory complaints (SMCs). This research examines the Association between sleep duration and self-reported SMC in a sample representing the entire United States. Methods: We examined data from 5567 individuals (aged 20–80) who participated in the National Health and Nutrition Examination Survey (2015–2018) to evaluate the association between sleep duration and SMC. Odds ratios (ORs) and a restricted cubic spline (RCS) curve were calculated with multiple logistic regression, and subgroup analysis was performed. Results: Approximately 5.8 % (323) reported SMC, and most are older people (163). RCS analysis treating sleep duration as a continuous variable revealed a J-shaped curve association between sleep duration and SMC. Self-reported sleep duration was significantly linked to a 33 % elevated risk of SMC (OR, 1.33; 95 % confidence interval [CI], 1.23–1.43; P

Abstract Santalum album is a well-known aromatic and medicinal plant that is highly valued for the essential oil (EO) extracted from its heartwood. In this study, we present a high-quality chromosome-level genome assembly of S. album after integrating PacBio Sequel, Illumina HiSeq paired-end and high-throughput chromosome conformation capture sequencing technologies. The assembled genome size is 207.39 M with a contig N50 of 7.33 M and scaffold N50 size of 18.31 M. Compared with three previously published sandalwood genomes, the N50 length of the genome assembly was longer. In total, 94.26% of the assembly was assigned to 10 pseudo-chromosomes, and the anchor rate far exceeded that of a recently released value. BUSCO analysis yielded a completeness score of 94.91%. In addition, we predicted 23,283 protein-coding genes, 89.68% of which were functionally annotated. This high-quality genome will provide a foundation for sandalwood functional genomics studies, and also for elucidating the genetic basis of EO biosynthesis in S. album.

Abstract Background Cultivated Hippeastrum × hybridum is a popular ornamental plant with large and colorful flowers, long flowering duration, and high commercial value. As its main ornamental feature, its flower color is related to the anthocyanin content in the tepals. However, the molecular regulatory mechanisms of anthocyanin biosynthesis in H. × hybridum have not yet been elucidated. Results In the present study, 12 cDNA libraries of four stages of H.× hybridum ‘Royal Velvet’ tepal development were used for RNA-seq, obtaining 79.83 gigabases (GB) of clean data. The data were assembled into 148,453 unigenes, and 11,262 differentially expressed genes were identified. Forty key enzymes participating in anthocyanin biosynthesis were investigated, and the results showed that most of the anthocyanin structural genes were expressed at low levels in S1 and were markedly upregulated in S2 and S3. The expression profiles of 12 selected genes were verified by qRT-PCR. Furthermore, the R2R3-MYB transcription factor (TF), HpMYB1, involved in the regulation of anthocyanin biosynthesis was identified by sequence, expression pattern, and subcellular localization analyses. Its overexpression in tobacco significantly increased the anthocyanin levels in various tissues and activated anthocyanin-related genes. Conclusions Using RNA-seq technology, we successfully identified a potential R2R3-MYB gene, HpMYB1, that regulates anthocyanin biosynthesis in H.× hybridum ‘Royal Velvet’. Our findings provide basic transcript information and valuable transcriptome data for further identification of key genes involved in anthocyanin biosynthesis and can be applied in the artificial breeding of new H. × hybridum cultivars with enhanced ornamental value.

Abstract Background Aglaonema commutatum ‘Red Valentine’, as a foliage ornamental plant, is widely used for interior and exterior decoration because of its easy cultivation and management. However, reduced proportion of red foliage during large-scale production of A. commutatum seedlings is a frequent occurrence, which has considerable implications on the plant’s ornamental and market value. However, the molecular mechanisms underlying this phenomenon remain unclear. Results To explore the molecular basis of the variation in leaf color of A. commutatum Red Valentine, we performed transcriptome sequencing with the Illumina platform using two different varieties of A. commutatum, namely Red Valentine and a green mutant, at three different stages of leaf development. We annotated 63,621 unigenes and 14,186 differentially expressed genes by pairwise comparison. Furthermore, we identified 26 anthocyanin biosynthesis structural genes. The transcript per million (TPM) values were significantly higher for Red Valentine than for the green mutant in all three developmental stages, consistent with the high anthocyanin content of Red Valentine leaves. We detected positive transcription factors that may be involved in the regulation of anthocyanin biosynthesis using BLAST and through correlation analysis. Downregulation of these transcription factors may downregulate the expression of anthocyanin genes. We obtained full-length cDNA of the anthocyanin biosynthesis and regulatory genes and constructed phylogenetic trees to ensure accuracy of the analysis. Conclusions Our study provides insights into the molecular mechanisms underlying leaf variation in A. commutatum Red Valentine and may be used to facilitate the breeding of ornamental cultivars with high anthocyanin levels.

Abstract Euryodendron excelsum H.T. Chang is a rare and endangered woody plant endemic to China. It is very important to conserve and propagate this species from extinction. In this study, leaves and petioles from the axillary shoots in vitro were used as explants to culture on the different plant growth regulator (PGR) woody plant medium (WPM) and establish an efficient shoot proliferation and plant regeneration system. WPM supplemented with 1.0 mg/L 2,4-D induced callus dedifferentiated into buds and somatic embryos on various media,including PGR-free WPM. However, only adventitious shoots formed on WPM with 1.0 mg/L of cytokinins such as 6-benzyladenine (BA), kinetin (KIN) or thidiazuron (TDZ). When another cytokinin, zeatin, was used, somatic embryos were induced directly from From cut surface of these explants. Adventitious roots could be induced from both explants on WPM with 1.0 mg/L α-naphthaleneacetic acid (NAA). Somatic embryos cultured in PGR-free WPM or WPM with 0.2 mg/L NAA developed roots. Plantlets derived from somatic embryos were transferred to a peat: sand (1:1, v/v) substrate, and showed survival rates of 64.3% at 30 days and 54.6% at 90 days. Callus clumps with adventitious shoot buds that were transferred to WPM containing 1.0 mg/L BA and 0.2 mg/L NAA generated a mean 3.3 multiple shoots. Callus-derived shoots regenerated and rooted successfully (100%) on agar-free vermiculite-based WPM with 0.5 μM NAA after 30 d. Plantlets transplanted to peat soil: vermiculite (1:1, v/v) displayed the highest survival (96.7%) after three months.

Objective: To investigate the protective and delayed effects of Gastrodia elata polysaccharide on non-alcoholic fatty liver (NAFLD) and its molecular mechanism. Methods:60 ICR mice were randomly divided into normal group, model group and Gastrodia elata polysaccharide group (50, 100 and 200 mg/kg). Except the normal group, the other groups were given high-fat diet to induce NAFLD model. At the same time, the corresponding drugs were given once a day for 10 weeks. At 30 min after the last administration, the body weight and organ index of mice were recorded, the pathological changes of liver tissue were evaluated by histopathology. At the same time, the activity of serum aspartate amino transferase (AST) and alanine amino transferase (ALT) were measured, and the related signal transduction pathways were examined including oxidative stress injury and lipid metabolism. Results:Compared with the model group, the activity of AST and ALT in serum were significantly decreased (P

Abstract Background Paphiopedilum, commonly known as slipper orchid, is an important genus of orchid family with prominent horticultural value. Compared with conventional methods such as tillers and in vitro shoots multiplication, induction and regeneration of protocorm-like bodies (PLBs) is an effective micropropagation method in Paphiopedilum. The PLB initiation efficiency varies among species, hybrids and varieties, which leads to only a few Paphiopedilum species can be large-scale propagated through PLBs. So far, little is known about the mechanisms behind the initiation and maintenance of PLB in Paphiopedilum. Results A protocol to induce PLB development from seed-derived protocorms of Paphiopedilum SCBG Huihuang90 (P. SCBG Prince × P. SCBG Miracle) was established. The morphological characterization of four key PLB developmental stages showed that significant polarity and cell size gradients were observed within each PLB. The endogenous hormone level was evaluated. The increase in the levels of indoleacetic acid (IAA) and jasmonic acid (JA) accompanying the PLBs differentiation, suggesting auxin and JA levels were correlated with PLB development. Gibberellic acid (GA) decreased to a very low level, indicated that GA inactivation may be necessary for shoot apical meristem (SAM) development. Comparative transcriptomic profiles of four different developmental stages of P. SCBG Huihuang90 PLBs explore key genes involved in PLB development. The numbers of differentially expressed genes (DEGs) in three pairwise comparisons (A vs B, B vs C, C vs D) were 1455, 349, and 3529, respectively. KEGG enrichment analysis revealed that DEGs were implicated in secondary metabolite metabolism and photosynthesis. DEGs related to hormone metabolism and signaling, somatic embryogenesis, shoot development and photosynthesis were discussed in detail. Conclusion This study is the first report on PLB development in Paphiopedilum using transcriptome sequencing, which provides useful information to understand the mechanisms of PLB development.

Abstract Sandalwood (Santalum album L.) is highly valued for its fragrant heartwood and extracted oil. Santalols, which are the main components of that oil, are terpenoids, and these are biosynthesized via the mevalonic acid (MVA) pathway. Mevalonate kinase (MK) and phosphomevalonate kinase (PMK) are key enzymes in the MVA pathway. Little is known about the genes that encode MK and PMK in S. album or the mechanism that regulates their expression. To isolate and identify the functional genes involved in santalol biosynthesis in S. album, an MK gene designated as SaMK, and a PMK gene designated as SaPMK, were cloned from S. album. The sequences of these genes were analyzed. A bioinformatics analysis was conducted to assess the homology of SaMK and SaPMK with MK and PMK genes from other plants. The subcellular localization of SaMK and SaPMK proteins was also investigated, as was the functional complementation of SaMK and SaPMK in yeast. Our results show that the full-length cDNA sequences of SaMK and SaPMK were 1409 bp and 1679 bp long, respectively. SaMK contained a 1381 bp open reading frame (ORF) encoding a polypeptide of 460 amino acids and SaPMK contained a 1527 bp ORF encoding a polypeptide of 508 amino acids. SaMK and SaPMK showed high homology with MK and PMK genes of other plant species. Functional complementation of SaMK in a MK-deficient mutant yeast strain YMR208W and SaPMK in a PMK-deficient mutant yeast strain YMR220W confirmed that cloned SaMK and SaPMK cDNA encode a functional MK and PMK, respectively, mediating MVA biosynthesis in yeast. An analysis of tissue expression patterns revealed that SaMK and SaPMK were constitutively expressed in all the tested tissues. SaMK was highly expressed in young leaves but weakly expressed in sapwood. SaPMK was highly expressed in roots and mature leaves, but weakly expressed in young leaves. Induction experiments with several elicitors showed that SaMK and SaPMK expression was upregulated by methyl jasmonate. These results will help to further study the role of MK and PMK genes during santalol biosynthesis in S. album.

Aglaonema commutatum is one of the most popular foliage plants with abundant leaf phenotypes; therefore, anthocyanin coloration is a vital economic trait in A. commutatum. However, the molecular mechanisms underlying anthocyanin biosynthesis and its regulation remain unclear. In this study, AcMYB1 and AcbHLH1, transcription factor genes related to an R2R3-myeloblast (MYB) and a basic helix–loop–helix (bHLH), respectively, were isolated from A. commutatum “Red Valentine” and functionally characterized. AcMYB1 and AcbHLH1 were found to interact by Y2H and BiFC assay. AcMYB1 was grouped into the AN2 subgroup and shared high homology with the known regulators of anthocyanin biosynthesis. Gene expression analysis showed that both AcMYB1 and AcbHLH1 have similar expression patterns to anthocyanin structural genes and correlate with anthocyanin distribution in different tissues of A. commutatum. Light strongly promoted anthocyanin accumulation by upregulating the expression of anthocyanin-related genes in A. commutatum leaves. Ectopic expression of AcMYB1 in tobacco remarkably increased anthocyanin accumulation in both vegetative and reproductive tissues at various developmental stages. These results provide insights into the regulation of anthocyanin biosynthesis in A. commutatum and are useful for breeding new A. commutatum cultivars with enhanced ornamental value.

Abstract Sandalwood (Santalum album L.) is famous for its unique fragrance derived from the essential oil of heartwood, whose major components are santalols. To understand the mechanism underlying the biosynthesis of santalols, in this study, we cloned two related genes involved in the mevalonate pathway in S. album coding for acetyl-CoA C-acetyl transferase (AACT) and 3-hydroxy-3-methyglutary-CoA synthase (HMGS). These genes were characterized and functionally analyzed, and their expression profiles were also assessed. An AACT gene designated as SaAACT (GenBank accession No. MH018694) and a HMGS gene designated as SaHMGS (GenBank accession No. MH018695) were successfully cloned from S. album. The deduced SaAACT and SaHMGS proteins contain 415 and 470 amino acids, and the corresponding size of their open-reading frames is 1538 bp and 1807 bp, respectively. Phylogenetic trees showed that the SaAACT protein had the closest relationship with AACT from Hevea brasiliensis and the SaHMGS proteins had the highest homology with HMGS from Siraitia grosvenorii. Functional complementation of SaAACT and SaHMGS in a mutant yeast strain deficient in these proteins confirmed that SaAACT and SaHMGS cDNA encodes functional SaAACT and SaHMGS that mediate mevalonate biosynthesis in yeast. Tissue-specific expression analysis revealed that both genes were constitutively expressed in all examined tissues (roots, sapwood, heartwood, young leaves, mature leaves and shoots) of S. album, both genes showing highest expression in roots. After S. album seedlings were treated with 100 μM methyl jasmonate, the expression levels of SaAACT and SaHMGS genes increased, suggesting that these genes were responsive to this elicitor. These studies provide insight that would allow further analysis of the role of genes related to the sandalwood mevalonate pathway in the regulation of biosynthesis of sandalwood terpenoids and a deeper understanding of the molecular mechanism of santalol biosynthesis.

Abstract An efficient regeneration system via shoot organogenesis and somatic embryogenesis from in vitro leaf and root explants was established for Scaevola sericea for the first time. The highest axillary shoot proliferation coefficient (4.8) was obtained on Murashige and Skoog (MS) medium supplemented with 1.0 mg/L 6-benzyladenine (BA) and 0.1 mg/L α-naphthaleneacetic acid (NAA) every 45 days. Young in vitro leaves and roots, which were used as explants, were cultured onto medium supplemented with different plant growth regulators. Our results showed that only cytokinins BA and thidiazuron (TDZ), could induce adventitious shoots and somatic embryos from leaf and root explants. The optimal medium to achieve this was MS medium supplemented with 2.5 mg/L BA and which induced most adventitious shoots (2.7) and somatic embryos (17.3) from leaf explants within 30 days. From root explants, 1.1 adventitious shoots and 7.6 somatic embryos could be induced on MS medium supplemented with 2.5 mg/L TDZ. Histological observation showed that both somatic embryos and adventitious shoots were originated from homogeneous parenchyma and the development of somatic embryos was visible. Maximum rooting percentage (99.0%) was achieved on half-strength MS medium supplemented with 2.5 mg/L NAA. Well-rooted plantlets, which were transplanted into a substrate of pure river sand, displayed a high survival percentage of 91.7% after transplanting for 45 days while the best substrate for plantlet growth was river sand: coral sand (1:1).

Abstract Backgrounds Paphiopedilum is an important genus of the orchid family Orchidaceae and has high horticultural value. The wild populations are under threat of extinction because of overcollection and habitat destruction. Mature seeds of most Paphiopedilum species are difficult to germinate, which severely restricts their germplasm conservation and commercial production. The factors inhibiting germination are largely unknown. Results In this study, large amounts of non-methylated lignin accumulated during seed maturation of Paphiopedilum armeniacum (P. armeniacum), which negatively correlates with the germination rate. The transcriptome profiles of P. armeniacum seed at different development stages were compared to explore the molecular clues for non-methylated lignin synthesis. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that a large number of genes associated with phenylpropanoid biosynthesis and phenylalanine metabolism during seed maturation were differentially expressed. Several key genes in the lignin biosynthetic pathway displayed different expression patterns during the lignification process. PAL, 4CL, HCT, and CSE upregulation was associated with C and H lignin accumulation. The expression of CCoAOMT, F5H, and COMT were maintained at a low level or down-regulated to inhibit the conversion to the typical G and S lignin. Quantitative real-time RT-PCR analysis confirmed the altered expression levels of these genes in seeds and vegetative tissues. Conclusions This work demonstrated the plasticity of natural lignin polymer assembly in seed and provided a better understanding of the molecular mechanism of seed-specific lignification process.

Background: Betaine aldehyde dehydrogenase (BADH) catalyzes the synthesis of glycine betaine and is considered to be a type of osmoregulator, so it can play a role in plants’ responses to abiotic stresses. Methods: In this study, a novel HuBADH gene from Hylocereus undatus (pitaya) was cloned, identified, and sequenced. The full-length cDNA included a 1512 bp open reading frame that encoded a 54.17 kDa protein consisting of 503 amino acids. Four oxidation-related stress-responsive marker genes (FSD1, CSD1, CAT1, and APX2) were analyzed by Quantitative real-time reverse transcription (qRT-PCR) in wild type (WT) and transgenic A. thaiana overexpression lines under NaCl stress. Results: HuBADH showed high homology (79–92%) with BADH of several plants. The HuBADH gene was genetically transformed into Arabidopsis thaliana and overexpressed in transgenic lines, which accumulated less reactive oxygen species than WT plants, and had higher activities of antioxidant enzymes under NaCl stress (i.e., 300 mM). All four marker genes were significantly upregulated in WT and HuBADH-overexpressing transgenic A. thaliana plants under salt stress. Glycine betaine (GB) content was 32–36% higher in transgenic A. thaliana lines than in WT in the control (70–80% in NaCl stress). Conclusions: Our research indicates that HuBADH in pitaya plays a positive modulatory role when plants are under salt stress.

Controlled release phosphorus (P) fertilizers and humic acid (HA) applications are two effective and significant techniques or measures for preventing P loss and enhancing maize development. However, the underlying physiological mechanism of how the controlled release P fertilizers combined with HA affect the maize production and P-use efficiency (PUE) remains unknown. The effects of applying coated diammonium phosphate (CDAP) and HA together on soil nutrient supply intensity, soil phosphatase activity, photosynthesis, endogenous hormone contents, and yield of maize, as well as PUE, were examined in this study. In a pot experiment, two types of P fertilizers—CDAP and diammonium phosphate (DAP)– as well as two HA application rates (0 and 45 kg ha–1) and two P levels (60 and 75 kg P2O5 ha–1) were utilized. Results showed that the key elements that influence the growth and yield of the maize were the availability of P content in soil, plant photosynthesis, and hormone levels. The combination of CDAP and HA had a greater impact on yield and PUE over the course of 2 years than either DAP alone or DAP combined with HA. Besides, using CDAP in combination with HA increased the yield and PUE by 4.2 and 8.4%, respectively, as compared to the application of CDAP alone at 75 kg P2O5 ha–1. From the twelve-leaf to milk stages, the available P content in the soil was increased by an average of 38.6% with the combination of CDAP and HA compared to the application of CDAP alone at 75 kg P2O5 ha–1. In addition, the application of CDAP combined with HA boosted the activities of ATP synthase, as well as the content of cytokinin (CTK), and hence improved the maize photosynthetic rate (Pn). When compared to the application of CDAP alone or DAP combined with HA, the Pn of CDAP + HA treatments was enhanced by 17.9–35.1% at the same P rate. In conclusion, as an environmentally friendly fertilizer, the combined application of CDAP and HA improved the intensity of the soil nutrient supply, regulated photosynthetic capabilities, and increased the yield and PUE, which is important for agricultural production, P resource conservation, and environmental protection.

NAC (NAM, ATAF1/2, and CUC2) proteins play a pivotal role in modulating plant development and offer protection against biotic and abiotic stresses. Until now, no systematic knowledge of NAC family genes is available for the food security crop, sweet potato. Here, a comprehensive genome-wide survey of NAC domain-containing proteins identified 130 ItbNAC and 144 ItfNAC genes with full length sequences in the genomes of two diploid wild relatives of cultivated sweet potato, Ipomoea triloba and Ipomoea trifida, respectively. These genes were physically mapped onto 15 I. triloba and 16 I. trifida chromosomes, respectively. Phylogenetic analysis divided all 274 NAC proteins into 20 subgroups together with NAC transcription factors (TFs) from Arabidopsis. There were 9 and 15 tandem duplication events in the I. triloba and I. trifida genomes, respectively, indicating an important role of tandem duplication in sweet potato gene expansion and evolution. Moreover, synteny analysis suggested that most NAC genes in the two diploid sweet potato species had a similar origin and evolutionary process. Gene expression patterns based on RNA-Seq data in different tissues and in response to various hormone, biotic or abiotic treatments revealed their possible involvement in organ development and response to various biotic/abiotic stresses. The expression of 36 NAC TFs, which were upregulated in the five tissues and in response to mannitol treatment, was also determined by real-time quantitative polymerase chain reaction (RT-qPCR) in hexaploid cultivated sweet potato exposed to drought stress. Those results largely corroborated the expression profile of mannitol treatment uncovered by the RNA-Seq data. Some significantly up-regulated genes related to drought stress, such as ItbNAC110, ItbNAC114, ItfNAC15, ItfNAC28, and especially ItfNAC62, which had a conservative spatial conformation with a closely related paralogous gene, ANAC019, may be potential candidate genes for a sweet potato drought tolerance breeding program. This analysis provides comprehensive and systematic information about NAC family genes in two diploid wild relatives of cultivated sweet potato, and will provide a blueprint for their functional characterization and exploitation to improve the tolerance of sweet potato to abiotic stresses.

The ecology, seed germination, seedling establishment, and reintroduction of Monochasma savatieri Franch. ex Maxim, a traditional Chinese hemiparasitic medicinal herb, were studied by focusing on the distribution, climate, soil type, flowering and seed production, co-occurring vegetation, and pollinators. The distribution range of M. savatieri lies between 25°03'-29°12' N to 113°39'-120°27' E, based on our sampling. M. savatieri requires vernalization to induce flowering. Seed germination was enhanced by gibberellic acid at an optimum concentration of 500 µM. Other plant growth regulators, including indole-3-acetic acid and 6-benzyladenine, did not enhance seed germination. Low temperature (5 °C) storage was favorable to keep seed viability, which was negatively influenced by increasingly long storage periods. We also examined seedling development and transplantation to the field. Seedlings were interplanted with a moss Hypnum plumaeforme, until they developed true leaves. Developed plants were then transplanted into the wild alongside a host, Gardenia jasminoides, and 23% of the transplanted plants survived after 8 months.

Abstract Background Clerodendrum inerme (L.) Gaertn, a halophyte, usually grows on coastal beaches as an important mangrove plant. The salt-tolerant mechanisms and related genes of this species that respond to short-term salinity stress are unknown for us. The de novo transcriptome of C. inerme roots was analyzed using next-generation sequencing technology to identify genes involved in salt tolerance and to better understand the response mechanisms of C. inerme to salt stress. Results Illumina RNA-sequencing was performed on root samples treated with 400 mM NaCl for 0 h, 6 h, 24 h, and 72 h to investigate changes in C. inerme in response to salt stress. The de novo assembly identified 98,968 unigenes. Among these unigenes, 46,085 unigenes were annotated in the NCBI non-redundant protein sequences (NR) database, 34,756 sequences in the Swiss-Prot database and 43,113 unigenes in the evolutionary genealogy of genes: Non-supervised Orthologous Groups (eggNOG) database. 52 Gene Ontology (GO) terms and 31 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were matched to those unigenes. Most differentially expressed genes (DEGs) related to the GO terms “single-organism process”, “membrane” and “catalytic activity” were significantly enriched while numerous DEGs related to the plant hormone signal transduction pathway were also significantly enriched. The detection of relative expression levels of 9 candidate DEGs by qRT-PCR were basically consistent with fold changes in RNA sequencing analysis, demonstrating that transcriptome data can accurately reflect the response of C. inerme roots to salt stress. Conclusions This work revealed that the response of C. inerme roots to saline condition included significant alteration in response of the genes related to plant hormone signaling. Besides, our findings provide numerous salt-tolerant genes for further research to improve the salt tolerance of functional plants and will enhance research on salt-tolerant mechanisms of halophytes.

Abstract Background It is well known that aromatic essential oils extracted from the heartwood of Santalum album L. have wide economic value. However, little is known about the role of terpenoids in response to various adverse environmental stresses as other plants do in the form of signals during plant-environment interactions. Results In this study, trace amounts of volatiles consisting of α-santalene, epi-β-santalene, β-santalene, α-santalol, β-santalol, (E)-α-bergamotene, (E)-β-farnesene and β-bisabolene were found in the leaves of mature S. album trees. We identified more than 40 candidate terpene synthase (TPS) unigenes by mining publicly-available RNA-seq data and characterized the enzymes encoded by three cDNAs: one mono-TPS catalyzes the formation of mostly α-terpineol, and two multifunctional sesqui-TPSs, one of which produces (E)-α-bergamotene and sesquisabinene as major products and another which catalyzes the formation of (E)-β-farnesene, (E)-nerolidol and (E,E)-farnesol as main products. Metabolite signatures and gene expression studies confirmed that santalol content is closely related with santalene synthase (SaSSY) transcripts in heartwood, which is key enzyme responsible for santalol biosynthesis. However, the expression of three new SaTPS genes differed significantly from SaSSY in the essential oil-producing heartwood. Increased activities of antioxidant enzymes, superoxide dismutase, catalase, peroxidase and ascorbate peroxidase, were detected in different tissues of S. album plants after applying 1 mM methyl jasmonate (MeJA) and 1 mM salicylic acid (SA), or exposure to 4°C, 38°C and high light intensity. MeJA and SA dramatically induced the expression of SaTPS1 and SaTPS2 in leaves. SaTPS1 to 3 transcripts were differentially activated among different tissues under adverse temperature and light stresses. In contrast, almost all SaSSY transcripts decreased in response to these environmental stresses, unlike SaTPS1 to 3. Conclusions Multifunctional enzymes were biochemically characterized, including one chloroplastic mono-TPS and two cytosolic sesqui-TPSs in sandalwood. Our results suggest the ecological importance of these three new SaTPS genes in defensive response to biotic attack and abiotic stresses in S. album.

Santalum album L., a semi-parasitic evergreen tree, contains economically important essential oil, rich in sesquiterpenoids, such as (Z) α- and (Z) β-santalol. However, their transcriptional regulations are not clear. Several studies of other plants have shown that basic-helix-loop-helix (bHLH) transcription factors (TFs) were involved in participating in the biosynthesis of sesquiterpene synthase genes. Herein, bHLH TF genes with similar expression patterns and high expression levels were screened by co-expression analysis, and their full-length ORFs were obtained. These bHLH TFs were named SaMYC1, SaMYC3, SaMYC4, SaMYC5, SabHLH1, SabHLH2, SabHLH3, and SabHLH4. All eight TFs had highly conserved bHLH domains and SaMYC1, SaMYC3, SaMYC4, and SaMYC5, also had highly conserved MYC domains. It was indicated that the eight genes belonged to six subfamilies of the bHLH TF family. Among them, SaMYC1 was found in both the nucleus and the cytoplasm, while SaMYC4 was only localized in the cytoplasm and the remaining six TFs were localized in nucleus. In a yeast one-hybrid experiment, we constructed decoy vectors pAbAi-SSy1G-box, pAbAi-CYP2G-box, pAbAi-CYP3G-box, and pAbAi-CYP4G-box, which had been transformed into yeast. We also constructed pGADT7-SaMYC1 and pGADT7-SabHLH1 capture vectors and transformed them into bait strains. Our results showed that SaMYC1 could bind to the G-box of SaSSy, and the SaCYP736A167 promoter, which SaSSy proved has acted as a key enzyme in the synthesis of santalol sesquiterpenes and SaCYP450 catalyzed the ligation of santalol sesquiterpenes into terpene. We have also constructed pGreenII 62-SK-SaMYC1, pGreenII 0800-LUC-SaSSy and pGreenII 0800-LUC-SaCYP736A167 via dual-luciferase fusion expression vectors and transformed them into Nicotiana benthamiana using an Agrobacterium-mediated method. The results showed that SaMYC1 was successfully combined with SaSSy or SaCYP736A167 promoter and the LUC/REN value was 1.85- or 1.55-fold higher, respectively, than that of the control group. Therefore, we inferred that SaMYC1 could activate both SaSSy and SaCYP736A167 promoters.

Abstract Background A great number of studies reported that 12/15-lipoxygenase (12/15-LO) played an important role in atherosclerosis. And its arachidonic acid(AA) metabolite, 15(S)-hydroperoxy-5,8,11,13-(Z,Z,Z,E)-eicosatetraenoic acid (15(S)-HETE), is demonstrated to mediate endothelial dysfunction. 15-oxo-5,8,11,13-(Z,Z,Z,E)-eicosatetraenoic acid (15-oxo-ETE) was formed from 15-hydroxyprostaglandin dehydrogenase (PGDH)-mediated oxidation of 15(S)-HETE. However, relatively little is known about the biological effects of 15-oxo-ETE in cardiovascular disease. Here, we explore the likely role of 15-lipoxygenase (LO)-1-mediated AA metabolism,15-oxo-ETE, in the early pathogenesis of atherosclerosis. Methods The 15-oxo-ETE level in serum was detected by means of liquid chromatography and online tandem mass spectrometry (LC-MS/MS). And the underlying mechanisms were illuminated by molecular techniques, including immunoblotting, MTT assay, immunocytochemistry and Immunohistochemistry. Results Increased 15-oxo-ETE level is found in in patients with acute myocardial infarction (AMI). After 15-oxo-ETE treatment, Human umbilical vein endothelial cells (HUVECs) showed more attractive to monocytes, whereas monocyte adhesion is suppressed when treated with PKC inhibitor. In ex vivo study, exposure of arteries from C57 mice and ApoE−/−mice to 15-oxo-ETE led to significantly increased E-selectin expression and monocyte adhesion. Conclusions This is the first report that 15-oxo-ETE promotes early pathological process of atherosclerosis by accelerating E-selectin expression and monocyte adhesion. 15-oxo-ETE -induced monocyte adhesion is partly attributable to activation of PKC.

Five chemical elicitors––6-benzyladenine (BA), ethephon (ETH), methyl jasmonate (MeJA), hydrogen peroxide (H2O2) and calcium chloride (CaCl2)––were used to treat 1- and 5-year-old sandal trees (Santalum album L.) to assess their effects on growth, heartwood formation and concrete oil synthesis. The results showed that some newly formed branches in stems that were induced by BA and ETH displayed leaf senescence and developed new smaller and light-green leaves. The relative percentage of concrete oil from the heartwood of water-treated trees (0.65%) was significantly lower than that from trees treated with 4 mM H2O2 (2.85%) and 4 mM BA (2.75%) within one year. Four mM BA, H2O2 and CaCl2 induced a significantly higher level of sesquiterpenoids than heartwood treated with 2 mM of these elicitors. Four mM MeJA induced significantly less sesquiterpenoids than heartwood treated with 2 mM MeJA. Morphological, physiological, and chromatographic–spectrometric technologies were integrated to trace the potential function of these exogenously applied chemical elicitors. The results may have important applications and provide a better understanding of the molecular mechanism of heartwood formation and hardening in young sandalwood trees.

In the present work, three NiTiNb alloys with nominal compositions of Ni50⁻x/2Ti50⁻x/2Nbx (x = 18, 20 and 22, at.%) were prepared. The microstructure, thermal-induced phase transformation, and phase components of NiTiNb hypoeutectic, eutectic, and hypereutectic alloys were investigated by scanning electron microscopy coupled with energy dispersive spectrometer (SEM/EDS), differential scanning calorimetry (DSC), and X-ray diffraction (XRD), respectively. Two peaks occurred in the DSC curves of Ni41Ti41Nb18 solution at 750 and 850 °C. The different microstructures of NiTiNb hypoeutectic, eutectic and hypereutectic alloys, the occurrence of two peaks in the DSC curves, and the characteristic of martensite transformation temperature were analyzed and discussed. The results show that different Nb content leads to different microstructures of Ni50⁻x/2Ti50⁻x/2-Nbx alloys. Moreover, the difference of Ni/Ti ratio between the primary NiTi matrix and NiTi in eutectic structure strongly influenced the phase transformation behavior that the DSC curves of Ni41Ti41Nb18 alloy show two peaks. Furthermore, under the same solution treatment, the Ni40Ti40Nb20 alloy has a lower Ms than the other two alloys. The Ms has a tendency to decrease with an increase in solution temperature.