Asymbiotic Seed Germination and In Vitro Seedling Development of the Endangered Orchid Species Cypripedium guttatum.

Cypripedium guttatum is a highly restricted terrestrial orchid that faces increasing endangerment owing to its habitat destruction and illegal collection. Compared to epiphytic orchids, terrestrial orchids such as C. guttatum have harder seed coats and more demanding in vitro germination conditions. This study aimed to develop an effective in vitro propagation system for C. guttatum to aid in its conservation. Seeds from mature capsules were subjected to various conditions, including sterilization using 1% sodium hypochlorite (NaOCl) and different light conditions, culture media, hormones, and organic supplements, to assess germination and early seedling development in vitro. Sterilization with 1% NaOCl significantly improved the germination rate, especially under dark conditions. Germination initiation occurred at 2 and 3 months in orchid seed sowing medium (OSM) and Murashige and Skoog (MS) medium, respectively. The addition of 1 mg/L naphthaleneacetic acid (NAA) further enhanced germination. However, the inclusion of organic supplements, such as apple and banana homogenates, in the culture medium led to substantial growth inhibition after 12 months. Notably, orchid maintenance medium (OMM) without organic additives proved to be the most suitable for seedling growth. The results of this study show that sterilization, appropriate light, and optimal NAA concentrations are beneficial for seed germination.

Analyte-mediated formation and growth of nanoparticles for the development of chemical sensors and biosensors.

The cornerstone of nanomaterial-based sensing systems is the synthesis of nanoparticles with appropriate surface functionalization that ensures their stability and determines their reactivity with organic or inorganic analytes. To accomplish these requirements, various compounds are used as additives or growth factors to regulate the properties of the synthesized nanoparticles and their reactivity with the target analytes. A different rationale is to use the target analytes as additives or growth agents to control the formation and properties of nanoparticles. The main difference is that the analyte recognition event occurs before or during the formation of nanoparticles and it is based on the reactivity of the analytes with the precursor materials of the nanoparticles (e.g., metal ions, reducing agents, and coatings). The transition from the ionic (or molecular) state of the precursor materials to ordered nanostructured assemblies is used for sensing and signal transduction for the qualitative detection and the quantitative determination of the target analytes, respectively. This review focuses on assays that are based on analyte-mediated regulation of nanoparticles' formation and differentiate them from standard nanoparticle-based assays which rely on pre-synthesized nanoparticles. Firstly, the principles of analyte-mediated nanomaterial sensors are described and then they are discussed with emphasis on the sensing strategies, the signal transduction mechanisms, and their applications. Finally, the main advantages, as well as the limitations of this approach, are discussed and compared with assays that rely on pre-synthesized nanoparticles in order to highlight the major advances accomplished with this type of nano-sensors and elucidate challenges and opportunities for further evolving new nano-sensing strategies.

Fine mapping and characterization of two novel quantitative trait loci for early seedling growth in rice.

MAIN CONCLUSION: Two novel QTLs for early seedling growth in rice were fine mapped, with one of which to a 4-kb identical to the known GW6a gene, and another one to a 43-kb region that contains six candidate genes. Leaves are extremely important for plant photosynthesis: the size and shape of which determine the rate of transpiration, carbon fixation and light interception, and their robust growth at seedling stage endow crops with the ability to compete with weeds. So far, many genes for the traits have been cloned with mutants; however, identification of those quantitative trait loci (QTLs) that control early seedling growth has seldom been reported. In this study, we report the identification of two QTLs, qLBL1 and qLBL2 on the rice chromosome 6 for leaf blade length at early seedling stage. Fine mapping revealed that qLBL1 was placed into a 4-kb, and qLBL2 was delimited to a 43-kb genomic interval. We further found that LBL1 was equivalent to the known grain-size gene GW6a and the qLBL2 region contains 6 candidate genes. Genetic analysis using nearly isogenic lines and transgenic rice plants revealed that both genetic factors were positive regulators. The genetic effects were mainly due to alterations of cell division by cytological observations. RT-qPCR results showed that LBL1 was preferentially expressed in leaf blades, and consistently, histochemical staining of pGW6a::GUS plants showed that GUS signal was strong in the vascular tissues of leaf blade of seedlings. Thus, we fine mapped and characterized two QTLs for early seedling growth and provided useful information to improve crop breeding.

Biotin plays an important role in Arabidopsis thaliana seedlings under carbonate stress.

Globally, many saline-alkali soils are rich in NaHCO3 and Na2CO3, which are characterized by a high pH Carbonate stress caused by this kind of soil severely damages plant cells and inhibits plant growth. Biotin and HCO3- participate in the first and rate-limiting reaction of the fatty acid biosynthesis pathway, but whether biotin contributes to plant responses to carbonate stress is unclear. In this study, we revealed that high carbonate and biotin concentrations inhibited Arabidopsis (Arabidopsis thaliana) seedling growth. However, specific concentrations of carbonate and biotin decreased the inhibitory effects of the other compound at the germination and seedling stages. Additionally, a carbonate treatment increased the endogenous biotin content and expression of AtBIO2, which encodes a biotin synthase. Moreover, phenotypic analyses indicated that the overexpression of AtBIO2 in Arabidopsis enhanced the tolerance to carbonate stress, whereas mutations to AtBIO2 had the opposite effect. Furthermore, the carbonate stress-induced accumulation of reactive oxygen species was lower in plants overexpressing AtBIO2 than in the wild-type and bio2 mutants. Accordingly, biotin, which is an essential vitamin for plants, can enhance the resistance to carbonate stress.

A New Strategy in Observer Modeling for Greenhouse Cucumber Seedling Growth.

State observer is an essential component in computerized control loops for greenhouse-crop systems. However, the current accomplishments of observer modeling for greenhouse-crop systems mainly focus on mass/energy balance, ignoring physiological responses of crops. As a result, state observers for crop physiological responses are rarely developed, and control operations are typically made based on experience rather than actual crop requirements. In addition, existing observer models require a large number of parameters, leading to heavy computational load and poor application feasibility. To address these problems, we present a new state observer modeling strategy that takes both environmental information and crop physiological responses into consideration during the observer modeling process. Using greenhouse cucumber seedlings as an instance, we sample 10 physiological parameters of cucumber seedlings at different time point during the exponential growth stage, and employ them to build growth state observers together with 8 environmental parameters. Support vector machine (SVM) acts as the mathematical tool for observer modeling. Canonical correlation analysis (CCA) is used to select the dominant environmental and physiological parameters in the modeling process. With the dominant parameters, simplified observer models are built and tested. We conduct contrast experiments with different input parameter combinations on simplified and un-simplified observers. Experimental results indicate that physiological information can improve the prediction accuracies of the growth state observers. Furthermore, the simplified observer models can give equivalent or even better performance than the un-simplified ones, which verifies the feasibility of CCA. The current study can enable state observers to reflect crop requirements and make them feasible for applications with simplified shapes, which is significant for developing intelligent greenhouse control systems for modern greenhouse production.

Mitigating biochar phytotoxicity via lanthanum (La) participation in pyrolysis.

Biochar (BC) produced from oak sawdust by slow pyrolysis was investigated to check the potential inhibition to early growth of tomato for phytotoxicity assessment. An inverted-U-shaped dose-response relationship between BC dosage and seed germination/seedling growth can be observed. Half maximal effective concentration (EC50), based on the inhibition rate of root and stem length, was 65.7 and 74.0 g kg-1, respectively. At the highest BC dosage of 80.0 g kg-1, germination rate, root, and shoot length were notably inhibited by 34.9, 62.3, and 62.2% compared with their corresponding controls (without BC). Fluorescence intensity, indicating reactive oxygen species (ROS) generation in leaf and root, was 177.7 and 344.5% higher than the control. Similar results on H2O2 content in leaf and root were observed as well. Besides, membrane leakage from the leaf and root cells was 2.1- and 1.3-fold higher than the corresponding controls. These results proved that BC exhibited significant phytotoxicity in the early growth stage of tomato. Unlike BC, the inhibitions on seed germination and seedling growth, the ROS accumulation, and the plasma membrane damage were not obvious with increasing La-BC dosage. These results indicated that BC phytotoxicity can be greatly mitigated by La involvement in pyrolysis, which was potentially associated with the reduced organic compounds and free radicals in La-BC. Besides, bio-available La in La-BC was partially involved in mitigating the phytotoxicity.

[Study on influence factors of seed germination and seeding growth of Lonicera macranthoides].

In order to improve reproductive efficiency and quality standard, the influence factors of seed germination and seeding growth of Lonicera macranthoides werew studied. The fruit and seed morphological characteristics of L. macranthoides were observed, the seed water absorbing capacity was determined, and different wet sand stratification time, temperature and germination bed treatment were set up. The effects of the parameters on seed germination and seedling growth were analysed. There was no obstacles of water absorption on L. macranthoides seed, quantity for 22 h water absorption was close to saturation. In the first 80 d, with the increase of the stratification time, seed initial germination time was shortened, germination rate and germination potential was improved. Stratification for 100 d, germination rate decreased. At 15 ℃, seed germination and seedling growth indicators were the best. The seedling cotyledon width in light was significantly higher than that in dark. Seeds on the top of paper and top of sand germination rate, germination potential, and germination index was significantly higher than that of other germination bed and mildew rate is low. The optimal conditions of seeds germination test was stratified in 4 ℃ wet sand for 80 d, 15 ℃ illuminate culture on the top of paper or top of sand. The first seeding counting time was the 4th day after beginning the test, the final time was the 23th day. The germination potential statistical time was the 13th day after beginning the test.

Study on influence factors of seed germination and seeding growth of Lonicera macranthoides / 中国中药杂志

In order to improve reproductive efficiency and quality standard, the influence factors of seed germination and seeding growth of Lonicera macranthoides werew studied. The fruit and seed morphological characteristics of L. macranthoides were observed, the seed water absorbing capacity was determined, and different wet sand stratification time, temperature and germination bed treatment were set up. The effects of the parameters on seed germination and seedling growth were analysed. There was no obstacles of water absorption on L. macranthoides seed, quantity for 22 h water absorption was close to saturation. In the first 80 d, with the increase of the stratification time, seed initial germination time was shortened, germination rate and germination potential was improved. Stratification for 100 d, germination rate decreased. At 15 ℃, seed germination and seedling growth indicators were the best. The seedling cotyledon width in light was significantly higher than that in dark. Seeds on the top of paper and top of sand germination rate, germination potential, and germination index was significantly higher than that of other germination bed and mildew rate is low. The optimal conditions of seeds germination test was stratified in 4 ℃ wet sand for 80 d, 15 ℃ illuminate culture on the top of paper or top of sand. The first seeding counting time was the 4th day after beginning the test, the final time was the 23th day. The germination potential statistical time was the 13th day after beginning the test.

Ordered gold nanoparticle arrays on glass and their characterization.

Using self-assembly of block copolymer micelle loaded metal precursors, combined with a seeding growth route, we have developed a novel approach to create ordered metal nanoparticle (NP) arrays of controllable size over large areas (~80 mm(2)) on solid substrates. Atomic force microscopy (AFM), UV-Vis extinction spectrophotometry, and theoretical simulations were systematically carried out to determine the size and pattern of NP arrays, and locate the localized surface plasmon resonance (LSPR) peak. By tuning the molar ratios of precursors, hexagonal arrays of AuNPs of mean heights of 5.2±0.6 nm, 8.3±1.7 nm, and 10.0±2.1 nm were obtained by self-assembly of poly(styrene-b-2-vinyl pyridine) micelle-loaded gold salt on glass. Further seeding growth was then used to enlarge the AuNPs to heights of 25.7 and 33 nm and decrease the edge-to-edge inter-particle spacing. The optical response of AuNP arrays was determined by measuring and computing their absorbance spectra as a function of the cover medium refractive index over the range from 1 to 1.55; the measured spectra agree very well with the computations. The resonance wavelength red-shifts as the medium refractive index increases and the bulk sensitivity of the arrays increases with increasing AuNP size. When the edge-to-edge inter-particle spacing decreased to ~50 nm, coupling of adjacent AuNPs became apparent, as a shoulder which developed in the spectra. Also, the AuNPs were found to be embedded in the substrate glass by about ~20-30%, as determined by comparing the experimental and computed bulk sensitivities. The fabrication technique devised is suitable for low-cost mass-manufacturing of large area arrays of ordered high-quality AuNPs on a substrate for biosensor or other applications.