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Euryodendron excelsum H. T. Chang, a critically endangered species endemic to China, is a source of valuable material for the furniture and construction industries. However, this species has some challenges associated with rooting during in vitro propagation that have yet to be resolved. In this study, we optimized rooting and conducted a transcriptomic analysis to appreciate its molecular mechanism, thereby promoting the practical application of in vitro propagation of E. excelsum, and providing technical support for the ecological protection of this rare and endangered species. Results showed that ex vitro rooting performed the highest rooting percentage with 98.33% at 25 d. During ex vitro rooting, there was a wide fluctuation of endogenous levels of indole-3-acetic acid (IAA) and hydrogen peroxide (H2O2) at the stage of root primordia formation. Transcriptome analysis revealed multiple differentially expressed genes (DEGs) involved in AR development. DEGs involved in plant hormone signal transduction, such as genes encoding auxin-induced protein, auxin-responsive protein, and IAA-amido synthetase Gretchen Hagen3, and in response to H2O2, oxidative stress, abiotic and biotic stimuli were significantly up- or down-regulated by ex vitro treatment with 1 mM indole-3-butyric acid (IBA). Our results indicate that ex vitro rooting is an effective method to induce AR from E. excelsum plantlets during micropropagation. DEGs involved in the plant hormone signal transduction pathway played a crucial role in AR formation. H2O2, produced by environmental stimulation, might be related to AR induction as a result of the synergistic action with IBA, ultimately regulating the level of endogenous IAA.

Lithium sulfur batteries have been paid much attention due to their high theoretical specific capacity of 1675 mAh·g−1. However, the low conductivity and shuttle efficiency hinder commercial application. Acetylene black (AB) and multi-wall carbon nanotube (CNT) interlayer coating on polyethylene glycol (PEG)–coated sulfur composite cathode (S/AB/CNT@PEG) can improve the electrochemical performance of the composite cathode. Comparing the electrochemical performance of these two interlayers, the S/AB/CNT@PEG cathode with CNT interlayer could more effectively improve electrochemical performance of the composite cathode. Moreover, it delivers an initial discharge specific capacity of 1660.4 mAh/g at 0.1 C and a discharge specific capacity of 803.3 mAh/g after 100 cycles at 1 C.

Cordia subcordata Lam. (Boraginaceae) is a woody tree that grows in coastal wasteland and mangrove edges. Its wood is used for woodcraft, and the tree, which is used in landscaping, also has medicinal and ecological value (e.g., coastal protection). In this study, a shoot proliferation and regeneration system was established for this plant. Callus was induced from terminal young leaf explants on Murashige and Skoog (MS) medium with 1.0 mg L–1 thidiazuron or 1.0 mg L–1 2,4-dichlorophenoxyacetic acid, or optimally with 0.5 or 1.0 mg L–1 of both. Callus differentiated from an average of 35.4% of explants into 3 to 5 adventitious shoots (indirect shoot organogenesis) within 45 d. Optimal shoot proliferation medium was MS medium with 0.8 mg L–1 6-benzyladenine (BA). A higher concentration of BA (1.5 mg L–1) in the presence of α-naphthaleneacetic acid (NAA) enhanced callus induction from the base of shoots and decreased shoot proliferation. On ½MS medium with 0.5 mg L–1 NAA and/or indole-3-butyric acid, adventitious roots were induced from shoots. Within 1 mo, 95.4% of plantlets transferred to a substrate of vermiculite and peat (1:1, v/v) survived.

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.

Thermo-sensitive genic male sterility (TGMS) is an important genetic means of two-line hybrid rice breeding. Pollen fertility in TGMS lines is regulated by a single point mutation in TGMS genes. Based on single nucleotide polymorphisms (SNPs) and insertion-deletion mutations, Kompetitive Allele-Specific PCR (KASP) markers were developed and utilized in rice molecular breeding via high-throughput detection, which saves time and money. In this study, we converted the SNPs on TGMS genes (including p/tms12-1and tms9-1) to functional co-dominant KASP markers and bred the resultant two-line hybrid rice. We differentiated the TGMS lines carrying p/tms12-1 or tms9-1 from other TGMS lines using the KASP assay. Pei’ai64S and Hua201S (containing p/tms12-1) had a homozygous GG genotype generating a blue signal. HengnongS-1 (containing tms9-1) had a homozygous CC genotype generating a red signal. The KASP assay for tms9-1 was identified as a recessive Mendelian trait. Seed purity was tested using the KASP marker for the two-line hybrid varieties of Liangyoupeijiu and Hualiangyou1206, which was consistent with findings by the dCAPS marker. Moreover, new TGMS lines were generated by pyramiding tms12-1 and tms9-1 gene under the same genetic background. Therefore, the KASP marker to detect the TGMS genes developed in this study can be widely used in two-line hybrid rice breeding. It provides a visually convenient toolkit for breeders to select individual target plants using high-throughput screening in two-line rice breeding.

Lepturus repens (G. Forst.) R. Br. is a perennial grass that grows on coral reef outcrops and sandy beaches and has drought tolerance and salt resistance. In this study, the internodes of L. repens were used as explants and cultured on Murashige and Skoog (MS) medium supplemented with 1.13 mg L−1 6-benzyladenine (BA) to successfully induce axillary shoots. Additional experimental results showed that cytokinins were a key factor for the successful induction and proliferation of shoots. BA induced 7.2 axillary shoots per explant, significantly more than kinetin (KIN), which induced 3.5 axillary shoots per explant. Shoots were proliferated more successfully on medium supplemented with 1.13 mg L−1 BA and a low concentration of 0.09 mg L−1 1-naphthaleneacetic acid (NAA) than BA alone. Shoot bases were used as explants for embryogenic callus induction and subsequent plant regeneration, which was possible on MS medium supplemented with 0.11 mg L−1 2,4-D, 0.09 mg L−1 NAA, and 0.22 mg L−1 TDZ. Separately, callus differentiated into adventitious shoot buds on MS medium containing 1.13 mg L−1 BA or 1.10 mg L−1 KIN singly or combined with 0.09 mg L−1 NAA. On MS medium without plant growth regulators (PGR-free) or only containing 0.09 mg L−1 NAA, callus induced both adventitious shoots and somatic embryos that developed a radical on PGR-free medium. All shoots formed roots on ½MS medium containing a low concentration (0.19 to 0.37 mg L−1) of NAA or IBA within 20 d. The survival percentage of plantlets with 3 to 4 shoot clusters exceeded 99% on a substrate consisting of yellow mud, organic fertilizer, and perlite (10:3:1, v:v:v). After transplanting, plantlets with one or two shoot clusters showed 68 to 86% survival within 1 mo.

To investigate the mechanisms underlying salt tolerance, physiological parameters of six halophyte species [Vitex rotundifolia L., Clerodendrum inerme (L.) Gaertn, Phyla nodiflora (L.) Greene, Scaevola sericea Vahl, Alternanthera bettzickiana (Regel) Nichols, and Dracaena cambodiana Pierre ex Gagn] under NaCl stress in in vitro and in vivo culture tests were examined. Membership function analysis and cluster analysis divided the six species, based on their salt tolerance level, into three groups: Group 1 (highly salt tolerant) included C. inerme, A. bettzickiana and S. sericea; Group 2 (moderately salt tolerant) included P. nodiflora; Group 3 (weakly salt tolerant) included V. rotundifolia and D. cambodiana. In response to in vitro NaCl stress, all six species showed a significant increase in the activities of antioxidant enzymes. NaCl stress enhanced free proline content in the leaves of all six species. CAT, SOD activity and proline accumulation were significantly correlated with the growth of C. inerme, P. nodiflora and A. bettzickiana under in vitro NaCl treatment. We conclude that NaCl-tolerant plants may suffer slight damage within a certain salt concentration, as evidenced by the activities of antioxidant enzymes and the accumulation of free proline. Six halophytic species showed a different salt tolerance level under in vitro and in vivo culture tests, due to the activities of antioxidant enzymes and the accumulation of free proline.

Metasequoia glyptostroboides Hu et Cheng (dawn redwood), a known relict living fossil, is listed as a Class I rare and endangered tree in China. An efficient in vitro propagation protocol was established in this study to overcome the shortage of germplasm that cannot be compensated by conventional reproduction and as a way to preserve this tree. This objective was achieved by testing the effect of plant growth regulators (PGRs) on shoot propagation and root formation. Axillary shoots, which could be induced on PGR-free woody plant medium (WPM), were efficiently propagated on WPM supplemented with 16.0 µM zeatin and 2.5 µM indole-3-butyric acid. Improved rooting was possible on WPM supplemented with 0.05 µM α-naphthaleneacetic acid. Rooting was possible both in vitro in vermiculite-based PGR-free liquid culture and ex vitro in plastic bags containing perlite: vermiculite (1:1, v/v). This effective in vitro micropropagation protocol for M. glyptostroboides serves as a way to conserve this tree and provides an opportunity for mass production to alleviate strain on natural populations.

Nickel oxalate micro-spheres with core-shell structure of solid core and radiate shell were synthesized by precipitation method in a mixed water solution, with oxalic acid and nickel acetate as raw materials, through dropping ammonium hydroxide to adjust the solution pH value to about 8.0. Nickel microspheres with core-shell structure of solid core and porous shell were prepared by decomposing of nickel oxalate microspheres precursor at about 340 °C in argon atmosphere. The analyses of infrared spectroscopy (IR) indicates that the composition of the powders is nickel oxalate. The analyses of atomic absorption spectrometry (AAS) and organic elemental analysis (OEA) indicate that the molar ratio of (C2O4)2−/Ni2+ is about 1.02, close to the theoretical value of 1.0. The results of the thermo-gravimetric and differential thermal gravity analyses (TG-DTG) indicate that the molar ratio of (C2O4)2−/Ni2+ is about 1.06, also close to the theoretical value of 1.0. The analysis of X-ray diffraction (XRD) indicates that the composition of black powders as-prepared is nickel, which has a face-centered cubic crystal structure with average crystal grain size about 16.87 nm. The images of scanning electron microscopy (SEM) indicate that the morphology of nickel oxalate microspheres is a core-shell structure with solid core and radiate shell. The diameter of nickel oxalate microspheres is about 3 μm, and the shell consists of a large number of thin nanorods. The images of SEM also indicate that the morphology of nickel microspheres is a core-shell structure with solid core and porous shell. The diameter of nickel microspheres is about 2 μm, and the shell consists of a large number of nickel grains, surface holes and through holes. The diameter of nickel grains is about 50–100 nm, and the diameter of holes is about 50–200 nm.

Euryodendron excelsum H. T. Chang is a single-type, rare and endangered woody plant unique to China. In this study, young stems were used as explants and cultured on Woody Plant Medium (WPM) supplemented with 5.0 μM 6-benzyladenine (BA), were subcultured for more than 15 times over a total of more than 3 years and finally an efficient axillary shoot proliferation and plantlet regeneration system was established in which one shoot could proliferate an average of 5.1 axillary shoots every 2 months on the medium supplemented with 5.0 μM BA and 0.5 μM α-naphthaleneacetic acid (NAA). Shoots rooted at a moderate frequencies (50.1%) on agarized WPM supplemented with 0.5 μM NAA but 100% of shoots rooted in agar-free vermiculite-based WPM after culture for 2 months. Plantlets, when transplanted to peat soil: vermiculite (1:1), showed the highest 95.1% survival within 1 month.

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.

The inducible accumulation of desired products via in vitro cultures provides an experimental system for researching secondary metabolism in woody plants. This system is convenient, because environmental conditions can be strictly controlled. This is particularly important for East Indian sandalwood (Santalum album L.), a tree with desired sandal oil products that are restricted to the heartwood. In this study, we established a method to induce and proliferate callus from sandalwood shoot explants. Thidiazuron (TDZ) (0.2–1.5 mg/l) could induce the formation of callus, which proliferated rapidly within a month following three successive subcultures in liquid shake culture on Murashige and Skoog (MS) basal medium supplemented with 0.8–1.0-mg/l TDZ. Callus cultured in this liquid medium for 7 days was co-cultured with fungi, either Colletotrichum gloeosporioides or Penidiella kurandae. Gas chromatography–mass spectrometry (GC–MS) analysis of the solvent extract by chemical anhydrous diethyl ether of callus co-cultured with C. gloeosporioides showed the presence of santalenes and bisabolene, which are the precursors of santalol. However, another fungus, P. kurandae, could not induce santalenes or bisabolene. This study provides an opportunity to further studies on the santalene and bisabolene biosynthetic signaling pathway and the fungal endophyte–plant interaction in sandalwood.

Sandalwood essential oil or terpenoids are highly valued. This review summarizes several methods for increasing yields of sandalwood essential oil or terpenoids and the molecular mechanisms of sandalwood terpene biosynthesis. Sandalwood is highly valued for its aromatic heartwood and essential oil, which is not only broadly applied in the fragrance industry, but also has various biological activities: anti-cancer, anti-tumor, anti-viral, anti-diarrhoeal, etc. The main contributors of sandalwood essential oil fragrance are (Z)-α-santalol and (Z)-β-santalol. Global sandalwood resources are often in short supply because of slow growth, habitat destruction, illegal use of natural stocks, over exploitation, plant disease and insect pests. Thus, various methods are used to overcome these shortcomings to obtain more sandalwood essential oil or terpenoids. At first, an understanding of the molecular mechanism of sandalwood terpenoid biosynthesis is urgently required. Here, we review the mechanism of sandalwood terpenoid biosynthesis and multiple strategies for increasing the yield of essential oil and obtaining sandalwood terpenoids by biotechnological methods. Three major topics are discussed: (1) the metabolic pathway of sandalwood terpenoid biosynthesis, (2) how to obtain sandalwood terpenoids or essential oil by chemical synthesis, the application of elicitors and the plant cell culture, and (3) heterologous synthesis of sandalwood terpenoids.

A highly efficient protocol for the induction of adventitious shoots from young internode and root explants of a semiparasitic medicinal herb Monochasma savatieri Franch ex Maxim was developed. MS basal medium supplemented with 5 µM thidiazuron (TDZ) induced 32 adventitious shoots/explant, which was double the number obtained using the same concentration of 6-benzyladenine (BA). Hyperhydric shoots were observed when 10 µM of any cytokinin was added to MS media. Use of any cytokinin at 2.5 µM produced an average of 14–21 adventitious shoots/root explant. Shoots formed roots in vitro more effectively than α-naphthaleneacetic acid when indole-3-butyric acid and indole-3-acetic acid were used at 1.0 µM. Two-month-old rooted plantlets were transplanted to vermiculite and 70% survived after 4 months.

An in vitro culture protocol through somatic embryogenesis has been established for the F1 hybrid, Santalum yasi × S. album, S. album , and S. yasi. The spontaneous F1 hybrid, Santalum yasi × S. album and its maternal S. yasi and paternal S. album are economically important plant species due to their highly valued perfume oils. In vitro plant regeneration from nodal segments of these species and hybrid was studied. The optimal basal medium for shoot multiplication was Murashige and Skoog (MS) supplemented with 2.22–4.44 µM 6-benzyladenine (BA) and 1.07–2.69 µM α-naphthaleneacetic acid (NAA) in S. album × S. yasi and S. album or the same concentration range of BA and 2.85–5.71 µM indole-3-acetic acid for S. yasi. Lower concentrations of BA and NAA induced adventitious roots in S. yasi × S. album and S. album. Embryogenic callus was induced when S. album × S. yasi and S. album nodal segments were cultured on MS medium supplemented with 4.52–9.05 µM 2,4-dichlorophenoxy acetic acid (2,4-D). Friable embryogenic callus of S. yasi × S. album was subcultured onto MS medium containing 0.89 µM BA, 0–0.27 µM NAA or 1.44–5.77 µM gibberellic acid (GA3) for somatic embryo induction, maturation and germination. A low concentration of indole-3-butyric acid (0.98–2.46 µM) effectively lengthened stunted roots of germinated S. yasi × S. album somatic embryos. In S. album, embryogenic callus produced many globular somatic embryos when cultured on half-strength MS medium containing only 0.44–0.89 µM BA. These globular somatic embryos were germinated and matured on half-strength MS medium supplemented with 0.44 µM BA and 1.44 µM GA3. On MS medium free of plant growth regulators, S. album plantlets regenerated within 20–30 days. This study provides new opportunities for the exploitation and utilization of high-yielding Santalum species and hybrid.

Plant regeneration via direct shoot organogenesis and callus-mediated organogenesis from leaf explants of Chirita swinglei (Merr.) W. T. Wang was studied. Cytokinins played a crucial role in the direct formation of adventitious shoots, which originally appeared as small nodular protuberances and developed into adventitious shoots as culture period increased. These protuberances were similar to somatic embryos in external morphology, but their anatomical structure confirmed that these were shoots and not somatic embryos. The highest frequency of shoot buds was induced by 2.0 μM thidiazuron (TDZ) and 2.5 μM 6-benzyladenine (BA). Leaf explants produced the highest frequency of shoot buds (100%) on MS medium supplemented with both 2.0 μM TDZ and 2.5 μM BA. In the presence of 2.0 μM TDZ, leaf explants became swollen after culture for 15 d. Some shoot buds were observed after 20 d of culture. Shoot buds were clearly visible as culture period was extended from 35 to 45 d. Histological analysis revealed the presence of meristematic tissues coincident with shoot tips. Callus could also be induced from leaves when α-naphthaleneacetic acid (NAA) was used alone or in combination with TDZ and BA. Three types of callus, pink and friable, white and compact, and green-yellow and compact, formed, but only the latter two could differentiate into plantlets. Over 90% of plantlets survived after transplanting into sand or a mixture of sand, loessal clay, and vermiculite (1:1:1, v/v). This protocol provides an efficient method via two organogenic pathways, to mass produce and conserve C. swinglei, an attractive ornamental plant and important medicinal herb.

Lithium-sulfur batteries with a high theoretical specific capacity of 1672 mAh g−1 have been paid tremendous attention to serving as energy storage system. However, the dissolution of polysulfide intermediates could result in poor cycling stability of lithium-sulfur batteries and hinder its practical application. In this work, a novel neodymium oxide (Nd2O3) nanoparticle doped the oxidized-acetylene black/sulfur (H-AB/S@Nd2O3) composite has been synthesized through in situ chemical deposition and solvent dispersion. The as-oxidized acetylene black is served as the conductive carbon scaffold and the as-prepared Nd2O3 nanoparticles, acting as the additive of the H-AB/S composite, can effectively alleviate the loss of polysulfides. As a result, the sulfur-based composite with 5 wt% Nd2O3 nanoparticles exhibits the high specific capacity and excellent cycling stability. The initial discharge capacity is 1171 mAh g−1 at 0.1 C and remains at 748 mAh g−1 after 200 cycles with a capacity retention of 63.9%. Even at a high current density of 1 C, the electrode delivers a maximum discharge capacity of 700 mAh g−1after activation and the capacity retention is approximately 68% after 200 cycles.

Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) is a widely used technique to investigate gene expression levels due to its high throughput, specificity, and sensitivity. An appropriate reference gene is essential for RT-qPCR analysis to obtain accurate and reliable results. To date, no reliable reference gene has been validated for the economically tropical tree, sandalwood (Santalum album L.). In this study, 13 candidate reference genes, including 12 novel putative reference genes selected from a large set of S. album transcriptome data, as well as the currently used β-actin gene (ACT), were validated in different tissues (stem, leaf, root and callus), as well as callus tissue under salicylic acid (SA), jasmonic acid methyl ester (MeJA), and gibberellin (GA) treatments using geNorm, NormFinder, BestKeeper, Delta Ct and comprehensive RefFinder algorithms. Several novel candidate reference genes were much more stable than the currently used traditional gene ACT. ODD paired with Fbp1 for SA treatment, CSA and Fbp3 for MeJA treatment, PP2C and Fbp2 for GA treatment, as well as Fbp1 combined with Fbp2 for the total of three hormone treatments were the most accurate reference genes, respectively. FAB1A, when combined with PP2C, was identified as the most suitable reference gene combination for the four tissues tested, while the combination of HLMt, PPR and FAB1A were the most optimal reference genes for all of the experimental samples. In addition, to verify our results, the relative expression level of the SaSSy gene was evaluated by the validated reference genes and their combinations in the three S. album tissues and under MeJA treatment. The evaluated reference genes in this study will improve the accuracy of RT-qPCR analysis and will benefit S. album functional genomics studies in different tissues and under hormone stimuli in the future.

$$\hbox {LaCoO}_{3}$$ epitaxial films grown on (100) $$\hbox {SrTiO}_{3}$$ substrates were prepared by the simple polymer-assisted deposition successfully. Based on the characteristics by X-ray diffractometer, infrared spectroscopy and thermal analyzer, the influence of molecular weight of polyethyleneimine, heat-treatment condition, spin-coating speed on the crystallinity and epitaxial quality of $$\hbox {LaCoO}_{3}$$ films were discussed. It is found that the number of –NH groups plays a key role in the cation-chelation of polyethyleneimine. Comparatively, more –NH groups existing in polyethyleneimine with larger molecular weight contribute to the improvement of epitaxial quality of $$\hbox {LaCoO}_{3}$$ epitaxial film. When polyethyleneimine begins to release the bound metal ions, higher heat-treatment temperature and a relatively rapid rate of heating can effectively prevent nucleus from growing in other orientations, thereby improving the epitaxial quality of film. Besides, the choice of spin speed will directly affect the thickness and surface roughness of the film, and may even affect the structure and performance of the film. The results will help to understand the cation-chelation mechanism of polyethyleneimine in the polymer-assisted deposition and extend this simple method for preparation of epitaxial films.

Photosynthetic and morphological differences between suitable ( Dalbergia sissoo, Lonicera japonica ) and unsuitable ( Aquilaria sinensis ) hosts in their semiparasitic associations with Santalum album were assessed. Santalum album L. is an important semiparasitic tree whose roots join to host roots, through haustoria, to acquire water and nutrients. Yet little is known how different hosts affect S. album growth, photosynthetic performance and haustorial development. In this study, Dalbergia sissoo Roxb., a leguminous tree, and Lonicera japonica Thunb., a non-leguminous vine, were suitable hosts while Aquilaria sinensis (Lour.) Gilg, a non-leguminous tree, was not. The three host plants were cultivated with sandalwood seedlings for 1 year, inducing significant differences in net photosynthetic rate, stomatal conductance and transpiration rate, plant height, haustorial size and number of haustoria. S. album growth was strongly related to net photosynthetic rate, stomatal conductance and transpiration rate. Well-formed and frequently replaced haustoria in the good host D. sissoo likely enhanced metabolism and nutrient transport. Ultrastructural observations showed differences in the interfacial region and internal structure between finger parenchymal cells and host root cells, vascular tissue, the reaction of host root cells and penetration modes. Among them, the finger parenchymal cells in the haustoria that connected with hosts D. sissoo and L. japonica roots were rich in organelles, including mitochondria, endoplasmic reticulum and lysosomes. Numerous small vacuoles accumulated inside membranes of the host root cells and finger parenchymal cells. Many lysosomes were present at the interfacial region where large-scale digestion of the host root cells in D. sissoo and L. japonica occurred. In contrast, in the finger parenchymal cells of the haustoria that joined to A. sinensis roots, organelles were not that obvious and black-stained material at the interfacial regions was indistinct. The modes of invasion were also different. The finger parenchymal cells penetrated into the roots of hosts D. sissoo and L. japonica by cell membrane fusion, pressure and degrading enzymes while in A. sinensis, host root cells were surrounded by the finger parenchymal cells and were self-digested. Even though mature haustoria could penetrate into the root xylem of hosts D. sissoo and A. sinensis, the haustoria that connected with D. sissoo had a mature xylem while A. sinensis had not yet formed any vessel elements. In all S. album haustoria connected to the three host roots, the vascular system developed some xylem but no phloem was observed.

Monochasma savatieri Franch. ex Maxim is a perennial herb used in traditional Chinese medicine. In this study, we report on the semi-parasitism of M. savatieri for the first time and identify mosses (Hypnum plumaeforme and Funaria bygrometrica) as the primary host as well as 25 secondary host species. This species is well-suited to a subtropical hill and mountainous moist monsoon climate and grows well in hilly and sunny terrains. The anatomy of its semi-parasitic haustoria was also studied. A single strand of straight vessels branches out, and curved vessels are connected to the stele of the parent plant root rather than to the parent root directly. This might assist with the absorption of nutrients and can prevent backflow of nutrients. M. savatieri is becoming rare or even extinct in many areas. An understanding of the basic biology of this species, in particular the functioning of its haustoria, would enable further studies on its conventional as well as in vitro propagation.

Nickel tartrate precursor particles were synthesized by the liquid phase precipitation method in an ethanol-water-ammonia mixed solution, with tartaric acid and using nickel chlorate as raw materials, with the pH value controlled at 4.0, and the temperature controlled at 50 °C. Nickel particles with complicated morphology were prepared by the decomposition of nickel taratrate precursor particles at temperatures of 360, 380 and 400 °C, respectively. The study of infrared spectroscopy (IR) indicated that the product was pure nickel tartrate. The studies of the atomic absorption spectrometry (AAS) and organic elemental analysis (OEA) indicated that the molar ratio of Ni2+ to (C4H4O6)2− is close to 1:1. The studies of the differential scanning calorimeter and thermo-gravimetric analysis (DSC-TG) indicated that the chemical formula Ni2(C4H4O6)2·5H2O was confirmed. The studies of X-ray diffractions (XRD) indicated that the silvery white metal powders were pure Ni, with a face-centered cubic crystal structure. The images of scanning electron microscopy (SEM) showed that the morphology of metal Ni particles was obvious spherical and radiate. The diameter of nickel tartrate particles was about 60 μm, which consisted of many nanolathes; and the diameter of metal Ni particles was about 30 μm, which consisted of many lathes about 0.5 μm in thickness.

Curcuma attenuata is a highly valued ornamental. This study provides the first report on C. attenuata shoot organogenesis and plant regeneration. Immature anthers derived from 5 to 7 cm long inflorescences were isolated and cultured on different variations of Murashige and Skoog (MS) media to induce callus and then shoot organogenesis. When the 2-mm long anthers in which microspores were at the uninucleate developmental stage were cultured in the dark on MS medium containing 13.6 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 2.3 μM kinetin (KT) for 15 days and then transferred to 40 μmol m−2 s−1 fluorescent light for 30 days, the percentage callus induction reached 33.3 %. After callus was transferred to various differentiation media and cultured in the light, 33.1 % of all callus cultures could differentiate into adventitious shoots on MS medium supplemented with 22.0 μM 6-benzyladenine (BA), 0.53 μM α-naphthaleneacetic acid (NAA) and 1.4 μM thidiazuron (TDZ) after culturing for 60 days. Over 95 % of plantlets survived after transplanting plantlets into trays with a mixture of sand and perlite (2: 1) for 20 days. Chromosome number, determined from the root tips of young plantlets, indicated that all plantlets were diploid (2n = 84).

Primulina tabacum is a rare and endangered species that is endemic to China. Establishing an efficient regeneration system is necessary for its conservation and reintroduction. In this study, when leaf explants collected from plants grown in four ecotypes in China are incubated on Murashige and Skoog (MS) medium containing 5.0 μM thidiazuron (TDZ) for 30 days, then transferred to medium containing 5.0 μM 6-benzyladenine (BA), adventitious shoots are then observed. Conversely, when leaf explants are incubated on medium containing 5.0 μM BA for 30 days, then transferred to medium containing 5.0 μM TDZ, somatic embryogenesis is induced. This indicates that somatic embryogenesis and shoot organogenesis could be switched simply by changing the order of two cytokinins supplemented in the culture medium. Histological investigation has revealed that embryogenic cells are induced within 30 days following incubation of explants in medium containing TDZ. Only if embryogenic cells were induced, TDZ could enhance somatic embryogenesis and BA could stimulate shoot organogenesis. When comparing explants from different ecotypes, leaf explants from Zixiadong in Hunan Province could induce low numbers (1–2) of either somatic embryos or adventitious shoots on medium containing either 5.0 μM TDZ or 5.0 μM BA, respectively. Whereas, leaf explants from plants collected from the other three ecological habitats could induce 50–70 somatic embryos/adventitious shoots per explant. Moreover, somatic embryos could induce secondary somatic embryogenesis and adventitious shoots on different media. All regenerated shoots developed adventitious roots when these are transferred to rooting medium, and over 95% of plantlets have survived following acclimatization and transfer to a potting mixture (1:1, sand:vermiculite).

An efficient propagation and regeneration system via direct shoot organogenesis for an endangered species, Metabriggsia ovalifolia, was established. High activity cytokinins [6-benzyladeneine (BA) and thidiazuron (TDZ)] and low activity auxins [α-naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA)] could directly induce adventitious shoots from leaf or petiole explants within 5 weeks. Cytokinins (TDZ or BA) combined with auxin (NAA) in the induction media induced more adventitious shoots than when auxins or cytokinins were used alone. Adventitious shoots could be induced and also mass-propagated on media containing 2.5–5.0 μM TDZ (or BA) and 0.25–0.5 μM NAA. Adventitious roots differentiated at the proximal end of shoots on rooting media containing half-strength MS salts and 0.5 μM IBA, 0.5 μM NAA, 0.1% activated charcoal or no plant growth regulators. Over 90% of plantlets survived following acclimatization and transfer to a potting mixture (1:1, sand:vermiculite) in basins.

Ochna integerrima is a medicinal and ornamental plant in Southeastern Asia. It has been listed as a rare and endangered species in China. Here we studied the effects of plant growth regulators and their concentrations on the induction of somatic embryogenesis and shoot organogenesis from leaf and shoot explants of O. integerrima for the first time. Cytokinins played a crucial role in somatic embryogenesis and shoot organogenesis. Among them, a higher concentration of thidiazuron (10.0–15.0 μM TDZ) could induce both somatic embryogenesis and adventitious shoot formation whereas low concentrations of TDZ (5.0 μM) could only induce adventitious shoots. However, 6-benzyladenine (BA at 5–15 μM) could only induce adventitious shoots. Shoot explants induced more adventitious shoots and somatic embryos than leaf explants when cultured on medium with the same concentration (5–15 μM) of TDZ or 15 μM BA. Medium containing 0.5 μM α-naphthaleneacetic acid and 8 μM indole-3-butyric acid and 0.1% activated charcoal could induce adventitious roots within 1 month. An efficient mass propagation and regeneration system has been established.

The rare and endangered plant Primulina tabacum is a calciphilous perennial herb found only at the entrances of a small number of karst cave drainages in southern China. In a conservation effort, we identified potentially suitable habitats and reintroduced P. tabacum plantlets (propagated in vitro) to one historical and two new cave entrances. The transplanted seedlings survived (10%) at only one new location where a moss, Gymnostomiella longinervis Broth, existed. Our field observations indicate that it is probably impossible for this rare plant to naturally recolonize the places where it went extinct because the habitats have changed. Transplanted P. tabacum grew slower than wild P. tabacum. The transplanted P. tabacum performed especially well under the cover of the nursing moss. Positive interactions between species, i.e., nurse plant effects, are important for reintroduction of success. Although light and soil conditions also appeared to be critical for transplantation success, the presence of moss should be considered as a useful and convenient indicator of suitable habitat for P. tabacum. This study case suggests that the use of new propagation methods and nurse plants can facilitate the reintroduction of rare and endangered herbs.

Cytological and embryological studies on apomictic species Bothriochloa ischaemum L. were carried out. Our studies revealed that the chromosome number of its root apical cells was 40, indicating that it was a tetraploid cytotype. During the stage of microsporogenesis, meiosis seemed irregular, as the pairing chromosome number of microspore mother cell was more than 20. It was often found that some chromosomes did not assemble in the equatorial plane or moved to the two poles of the cell, a few laggards were seen. Multiporate pollens (22.3%) were often observed. The studies showed that a high frequency (87.8%) of 1-3 or more aposporous embryo sacs developed in one ovule of the species. The mature aposporous sac was usually characterized by an egg cell and one polar nucleus. The egg cell could develop spontaneously into a large proembryo (100-200 microm) mass prior to anthesis. When several aposporous sacs occurred in the same ovule, usually 2 aposporous sacs were involved in pseudogamy and developed into separate endosperm masses in the same ovary. In the low frequency of mature seed, 13.5% twin-embryo seedlings could be obtained after mature seeds germinated.

Burma reed (Neyraudia arundinacea Henr.) is a C4 grass native to Southeast Asia and Indomalaya that grows quickly, exhibits strong resistance to environmental stresses, and is extremely adaptable. It can be widely utilized as a bioenergy crop for biomass conversion. In vitro multiple shoots were first established from axillary buds and then subcultured on propagation medium containing 10 μM 6-benzylaminopurine (BA) and 2.0 μM naphthaleneacetic acid (NAA). Multishoot clumps were used as explants to induce somatic embryogenesis and adventitious shoot formation. The results showed that auxin 2,4-dichlorophenoxyacetic acid or NAA play a key role for the induction of somatic embryogenesis and adventitious shoot formation, whereas cytokinin BA or kineatin enhance shoot proliferation and plant regeneration from callus and somatic embryos. Efficient somatic embryogenesis, mass propagation, and plant regeneration systems in Burma reed were established.

A butenolide (3-methyl-2H-furo[2,3-c]pyran-2-one, the phyto-active compound isolated from smoke) was tested for its effect on somatic embryogenesis with an important species for commercial horticulture, Baloskion tetraphyllum. When somatic embryos of B. tetraphyllum were transferred to basal medium supplemented with butenolide, enhanced development of growth-competent somatic embryos was observed. This study demonstrates that butenolide exhibits promotive effects on both germination of seed (stimulation of zygotic embryos), and stimulation of development and maturation of somatic embryos with B. tetraphyllum, providing a potential new class of phyto-active compounds for in vitro culture.

Direct somatic embryogenesis was successfully achieved from immature leaves of cassava (Manihot esculenta Crantz) cultured on induction medium containing 2,4-dichlorophenoxyacetic acid or naphthaleneacetic acid. Changing the duration of induction or changing plant growth regulators resulted in differences in regeneration of somatic embryos or adventitious shoots. The results showed that auxin was a key factor for inducing embryogenic cells. The embryogenic cells were mainly induced within 4–12 days. Only if the embryogenic cells were induced, the auxin enhanced formation of somatic embryo whereas 6-benzylaminopurine stimulated development of adventitious shoots. Histological examinations supported the conclusion.

Via a mild thermal precipitation and aging process, polycrystalline hydrated nickel oxalate nanofibers were synthesized using nickel chloride and ammonium oxalate as raw materials, with pH 8.0 and temperature 60 °C. Atomic absorption spectrometer (AAS), organic elemental analyzer (OEA), fourier transform infrared spectroscopy (FT-IR), thermogravimetry-derivative thermogravimetry (TG-DTG), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to characterize the products properties. The results demonstrated that the product was hydrated nickel oxalate. The sizes of hydrated nickel oxalate nanofibers were 100–150 nm in diameter, and 0.5–5.0 μm in length. A rational mechanism based on coordination self-assembly was discussed for the selective formation of the polycrystalline hydrated nickel oxalate nanofibers.

The induction of adventitious buds from apical shoot explants of Euphorbia tirucalli was studied. On average, 10.5 adventitious buds were efficiently induced in a ring on the segment from one apical explant on MS (Murashige and Skoog) medium supplemented with 0.5 mg l−1 thidiazuron and 0.5 mg l−1 benzylaminopurine. The adventitious buds could develop into adventitious shoots during subsequent cultures on hormone-free MS medium. For rooting, shoot clumps were cultured on half-strength MS medium containing 0.2 mg l−1 α-naphthaleneacetic acid or indole-3-butyric acid. All the rooted plants survived establishment in soil within 2 months.