基于农艺性状指标的山西高粱地方品种核心种质构建

利用1285份山西省高粱地方品种18个农艺性状的历史数据,通过比较不同取样方法、取样比例和聚类方法组合的构建方法,确定了“多次聚类偏离度取样法+15%取样比例+欧氏距离+最长距离法”为山西省高粱地方核心种质构建的方法。192份初选核心种质和所有样本的均值差异百分率、方差差异百分率、极差符合率和变异系数变化率分别为0、83.33%、97.45%和119.63%。同时,在此基础上补充选择6个具有特殊性状但未选入的种质资源,最终确定198份高粱资源组成山西省高粱地方品种核心种质,取样量为15.4%。经核心种质和所有样本不同性状的均值t测验、极值和标准差比较、遗传多样性指数的t值检验以及主成分分析,最终得出核心种质的198份高粱资源能够代表山西省高粱地方品种的遗传多样性,为山西省高粱地方品种评价和利用提供了优先样本。     

Highly luminescent hybrid SiO2‐coated CdTe quantum dots: synthesis and properties

Novel hybrid SiO₂‐coated CdTe quantum dots (QDs) were created using CdTe QDs coated with a hybrid SiO₂ shell containing Cd²⁺ ions and a sulfur source via a sol–gel process in aqueous solution. Aqueous CdTe QDs with tunable emitting color created through a reaction between cadmium chloride and sodium hydrogen telluride was used as cores for the preparation of hybrid SiO₂‐coated CdTe QDs. In our experiments we found that the surface state of the cores and preparation conditions that affect the formation of the hybrid SiO₂ shell also greatly affect photoluminescence of the hybrid SiO₂‐coated CdTe QDs. The generation of CdS‐like clusters in the vicinity of the CdTe QDs, caused the quantum size effect of the QDs to be greatly reduced, which changes photoluminescence properties of the hybrid QDs fundamentally. Namely, the novel hybrid SiO₂ shell played an important role in generating a series of specific optical properties. In addition, the novel hybrid SiO₂ shell can be created if no CdTe QD is added. In order to gain an insight into the inter structure of the hybrid shell, we characterized the hybrid SiO₂‐coated CdTe QDs using X‐ray diffraction analysis and discuss the formation mechanism of such a hybrid structure. This work is significant because the novel hybrid SiO₂‐coated CdTe QDs with its excellent properties can be used in many applications, such as biolabeling and optoelectronic devices. Copyright © 2013 John Wiley & Sons, Ltd.     

Response of millet and sorghum to a varying water supply around the primary and nodal roots

Background and Aims

Cereals have two root systems. The primary system originates from the embryo when the seed germinates and can support the plant until it produces grain. The nodal system can emerge from stem nodes throughout the plant''s life; its value for yield is unclear and depends on the environment. The aim of this study was to test the role of nodal roots of sorghum and millet in plant growth in response to variation in soil moisture. Sorghum and millet were chosen as both are adapted to dry conditions.

Methods

Sorghum and millet were grown in a split-pot system that allowed the primary and nodal roots to be watered separately.

Key Results

When primary and nodal roots were watered (12 % soil water content; SWC), millet nodal roots were seven times longer than those of sorghum and six times longer than millet plants in dry treatments, mainly from an 8-fold increase in branch root length. When soil was allowed to dry in both compartments, millet nodal roots responded and grew 20 % longer branch roots than in the well-watered control. Sorghum nodal roots were unchanged. When only primary roots received water, nodal roots of both species emerged and elongated into extremely dry soil (0·6–1·5 % SWC), possibly with phloem-delivered water from the primary roots in the moist inner pot. Nodal roots were thick, short, branchless and vertical, indicating a tropism that was more pronounced in millet. Total nodal root length increased in both species when the dry soil was covered with plastic, suggesting that stubble retention or leaf mulching could facilitate nodal roots reaching deeper moist layers in dry climates. Greater nodal root length in millet than in sorghum was associated with increased shoot biomass, water uptake and water use efficiency (shoot mass per water). Millet had a more plastic response than sorghum to moisture around the nodal roots due to (1) faster growth and progression through ontogeny for earlier nodal root branch length and (2) partitioning to nodal root length from primary roots, independent of shoot size.

Conclusions

Nodal and primary roots have distinct responses to soil moisture that depend on species. They can be selected independently in a breeding programme to shape root architecture. A rapid rate of plant development and enhanced responsiveness to local moisture may be traits that favour nodal roots and water use efficiency at no cost to shoot growth.     

Evaluation of improved and local/landrace/sorghum varieties for covered kernel smut

Twelve varieties of improved and local (landrace) sorghum were tested under artificial inoculation conditions. Out of 12 sorghum varieties evaluated with covered kernel smut, notably local cultivar ‘Tetron’ was found to be highly resistant. Disease incidence and severity on the rest of the cultivars varied from 21 to 47% and 40 to 53% respectively. Differences among cultivars in yield loss were also observed. The highest yield loss (40%) was recorded on 97 MW 6129 (NVT-11 4) and for Tetron yield loss was nil. The effect of disease on germination was noticed but cannot be considered as conclusive due to moisture stress at the time of germination.     

Development and assessment of fusarium oxysporum-based mycoherbicide for control of Striga Hermonthica in sorghum

Abstract

Experiments were carried out from 2002 to 2003 to determine the most suitable form of fungal delivery for possible use by farmers in biological control of Striga hermonthica. Six mycoherbicides were developed, based on Fusarium oxysporum isolated from wilted S. hermonthica. In mycoherbicide formulation, rock phosphate powder, sorghum bran and gum arabic powder were used as carriers. Besides its role as a carrier, gum arabic powder was used as a sticker. There were three carriers with two formulations each, making six treatments altogether. Living propagule studies were based on colony, mycelium and conidium number of F. oxysporum. In greenhouse evaluation of mycoherbicides, each kg sorghum seed was coated with 10 g mycoherbicide before sowing. Carrier rock phosphate powder with gum arabic powder as a sticking agent was the most suitable form of its delivery for use by peasant farmers.     

Comparing methods for metabolic network analysis and an application to metabolic engineering

Bioinformatics tools have facilitated the reconstruction and analysis of cellular metabolism of various organisms based on information encoded in their genomes. Characterization of cellular metabolism is useful to understand the phenotypic capabilities of these organisms. It has been done quantitatively through the analysis of pathway operations. There are several in silico approaches for analyzing metabolic networks, including structural and stoichiometric analysis, metabolic flux analysis, metabolic control analysis, and several kinetic modeling based analyses. They can serve as a virtual laboratory to give insights into basic principles of cellular functions. This article summarizes the progress and advances in software and algorithm development for metabolic network analysis, along with their applications relevant to cellular physiology, and metabolic engineering with an emphasis on microbial strain optimization. Moreover, it provides a detailed comparative analysis of existing approaches under different categories.     

The calculation of structural,elastic and phase stability properties of minerals using first principles techniques: A comparison of HF,DFT and Hybrid functional treatments of exchange and correlation

We benchmark the performance of four treatments of electron exchange and correlation in the prediction of structural and elastic properties of a range of minerals. The treatments used are the Hartree-Fock (HF) theory, the local density approximation (LDA) and the generalised gradient approximation (GGA) to the density functional theory (DFT) and Becke's three parameter hybrid functional (B3LYP). We find that the hybrid functional, B3LYP method yields computed elastic properties in significantly better agreement to experiment than HF or DFT-LDA and performs at least as well, if not better than the most successful DFT-GGA functionals. We suggest that B3LYP is a simple, reliable and computationally efficient tool for the ab initio simulation of mineral systems.     

International Society of Chronobiology: Membership Information

Most variables of interest in laboratory medicine show predictable changes with several frequencies in the span of time investigated. The waveform of such nonsinusoidal rhythms can be well described by the use of multiple components rhythmometry, a method that allows fitting a linear model with several cosine functions. The method, originally described for analysis of longitudinal time series, is here extended to allow analysis of hybrid data (time series sampled from a group of subjects, each represented by an individual series). Given k individual series, we can fit the same linear model with m different frequencies (harmonics or not from one fundamental period) to each series. This fit will provide estimations for 2m + 1 parameters, namely, the amplitude and acrophase of each component, as well as the rhythm-adjusted mean. Assuming that the set of parameters obtained for each individual is a random sample from a multivariate normal population, the corresponding population parameter estimates can be based on the means of estimates obtained from individuals in the sample. Their confidence intervals depend on the variability among individual parameter estimates. The vari-ance-covariance matrix can then be estimated on the basis of the sample covariances. Confidence intervals for the rhythm-adjusted mean, as well as for the amplitude-acrophase pair, of each component can then be computed using the estimated covariance matrix. The p-values for testing the zero-amplitude assumption for each component, as well as for the global model, can finally be derived using those confidence intervals and the t and F distributions. The method, validated by a simulation study and illustrated by an example of modeling the circadian variation of heart rate, represents a new step in the development of statistical procedures in chronobiology.     

Towards a hybrid anaerobic digester-microbial fuel cell integrated energy recovery system: An overview of the development of an electrogenic biofilm

An electrogenic biofilm was developed on a macroporous chitosan-carbon nanotube (CHIT-CNT) electrode under constant poised potential (?0.25 V versus Ag/AgCl reference electrode) and flow through conditions utilizing the effluent of an anaerobic digester as both the inoculant and substrate for the electrogenic biofilm. After 125 days of inoculation the bioelectrode demonstrated an open circuit potential of ?0.62 V and a current density of 9.43 μA cm^?3 (at ?0.25 V). Scanning electron microscopy images indicate thorough surface coverage of the biofilm with a high density of bacterial nanowires physically connecting bacteria to bacteria and bacteria to carbon nanotube (electrode surface) suggesting the nanowires are electrically conductive. DGGE was used to identify the major bacterial and archaeal populations.     

CHROMOSOMAL REARRANGEMENTS AND THE GENETICS OF REPRODUCTIVE BARRIERS IN MIMULUS (MONKEY FLOWERS)

Chromosomal rearrangements may directly cause hybrid sterility and can facilitate speciation by preserving local adaptation in the face of gene flow. We used comparative linkage mapping with shared gene‐based markers to identify potential chromosomal rearrangements between the sister monkeyflowers Mimulus lewisii and Mimulus cardinalis, which are textbook examples of ecological speciation. We then remapped quantitative trait loci (QTLs) for floral traits and flowering time (premating isolation) and hybrid sterility (postzygotic isolation). We identified three major regions of recombination suppression in the M. lewisii × M. cardinalis hybrid map compared to a relatively collinear Mimulus parishii × M. lewisii map, consistent with a reciprocal translocation and two inversions specific to M. cardinalis. These inferences were supported by targeted intraspecific mapping, which also implied a M. lewisii‐specific reciprocal translocation causing chromosomal pseudo‐linkage in both hybrid mapping populations. Floral QTLs mapped in this study, along with previously mapped adaptive QTLs, were clustered in putatively rearranged regions. All QTLs for male sterility, including two underdominant loci, mapped to regions of recombination suppression. We argue that chromosomal rearrangements may have played an important role in generating and consolidating barriers to gene flow as natural selection drove the dramatic ecological and morphological divergence of these species.