Impacts of long-term plant biomass management on soil phosphorus under temperate grassland

Aims

We assessed and quantified the cumulative impact of 20 years of biomass management on the nature and bioavailability of soil phosphorus (P) accumulated from antecedent fertiliser inputs.

Methods

Soil (0–2.5, 2.5–5, 5–10 cm) and plant samples were taken from replicate plots in a grassland field experiment maintained for 20 years under contrasting plant biomass regimen- biomass retained or removed after mowing. Analyses included dry matter production and P uptake, root biomass, total soil carbon (C), total nitrogen (N), total P, soil P fractionation, and ³¹P NMR spectroscopy.

Results

Contemporary plant production and P uptake were over 2-fold higher for the biomass retained compared with the biomass removed regimes. Soil C, total P, soluble and labile forms of inorganic and organic soil P were significantly higher under biomass retention than removal.

Conclusions

Reserves of soluble and labile inorganic P in soil were significantly depleted in response to continued long-term removal of P in plant biomass compared to retention. However, this was only sufficient to sustain plant production at half the level observed for the biomass retention after 20 years, which was partly attributed to limited mobilisation of organic P in response to P removal.

     

Calcium carbonate-methylene blue nanohybrids for photodynamic therapy and ultrasound imaging

Photodynamic therapy plays an important role in cancer treatment. In this work, methylene blue (MB)-embedded calcium carbonate nanorods (CaCO₃-MB NRs) have been synthesized for pH-responsive photodynamic therapy and ultrasound imaging. The morphology of CaCO₃-MB NRs can be controlled by modulating the concentration of Na₂CO₃ aqueous solution. The generation of effective reactive oxygen species (ROS) were confirmed by 1,3-diphenylisobenzofuran (DPBF) probe. Both photodynamic therapy performance and echogenic performance of CaCO₃-MB NRs were investigated to confirm the feasibility of CaCO₃-MB nanohybrids for ultrasound image-guided photodynamic therapy.     

Structure for energy cycle: a unique status of the second law of thermodynamics for living systems

Distinguishing things from beings, or matters from lives, is a fundamental question. Extending E. Schr?dinger's neg-entropy and I. Prigogine's dissipative structure, we propose a chemical kinetic view that the earliest "live" process is embedded essentially in a special interaction between a pair of specific components under a particular, corresponding environmental conditions. The interaction exists as an inter-molecular-force-bond complex(IMFBC) that couples two separate chemical processes: one is the spontaneous formation of the IMFBC driven by a decrease of Gibbs free energy as a dissipative process; while the other is the disassembly of the IMFBC driven thermodynamically by free energy input from the environment. The two chemical processes coupled by the IMFBC originated independently and were considered non-living on Earth, but the IMFBC coupling of the two can be considered as the earliest form of metabolism: the first landmark on the path from things to a being. The dynamic formation and disassembly of the IMFBC, as a composite individual, follows a principle designated as "… structure for energy for structure for energy…", the cycle continues; and for short it will be referred to as "structure for energy cycle". With additional features derived from this starting point, the IMFBC-centered "live" process spontaneously evolved into more complex living organisms with the characteristics currently known.     

Optimal Mating Strategies for Preferentially Outcrossing Simultaneous Hermaphrodites in the Presence of Predators

The optimal timing for initiating reproduction (i.e., the age at first reproduction) is a critical life history trait describing aspects of an individual’s resource-allocation strategy. Recent theoretical and empirical work has demonstrated that this trait is also tied to mating system expression when individuals have the opportunity to reproduce via both self-fertilization and cross-fertilization. A strategy of “delayed selfing” has emerged as a “best of both worlds” arrangement where, in the absence of a mate, an individual will delay reproduction (selfing) to “wait” for a mate. Herein, we extend previously developed predictive optimization models for the timing of reproduction to a situation where organisms can allocate their resources to size-dependent and size-independent defensive strategies to counter the threat of predation. By incorporating inducible defenses into a predictive framework for analyzing life history expression and evolution, we can more accurately evaluate the role that allocation strategy plays in altering the optimal waiting time. We compare our model to previous models and empirical results highlighting that incorporation of inducible defenses into the model broadens the parameter space in which a waiting time is expected and often leads to a predicted waiting time that is longer than in the situation without inducible defenses. In particular, a waiting time is predicted to exist regardless of the strength of inbreeding depression in the population.     

Mapping and validation of a new QTL for adult-plant resistance to powdery mildew in Chinese elite bread wheat line Zhou8425B

Key message

Four QTLs for adult-plant resistance to powdery mildew were mapped in the Zhou8425B/Chinese Spring population, and a new QTL on chromosome 3B was validated in 103 wheat cultivars derived from Zhou8425B.

Abstract

Zhou8425B is an elite wheat (Triticum aestivum L.) line widely used as a parent in Chinese wheat breeding programs. Identification of genes for adult-plant resistance (APR) to powdery mildew in Zhou8425B is of high importance for continued controlling the disease. In the current study, the high-density Illumina iSelect 90K single-nucleotide polymorphism (SNP) array was used to map quantitative trait loci (QTL) for APR to powdery mildew in 244 recombinant inbred lines derived from the cross Zhou8425B/Chinese Spring. Inclusive composite interval mapping identified QTL on chromosomes 1B, 3B, 4B, and 7D, designated as QPm.caas-1BL.1, QPm.caas-3BS, QPm.caas-4BL.2, and QPm.caas-7DS, respectively. Resistance alleles at the QPm.caas-1BL.1, QPm.caas-3BS, and QPm.caas-4BL.2 loci were contributed by Zhou8425B, whereas that at QPm.caas-7DS was from Chinese Spring. QPm.caas-3BS, likely to be a new APR gene for powdery mildew resistance, was detected in all four environments. One SNP marker closely linked to QPm.caas-3BS was transferred into a semi-thermal asymmetric reverse PCR (STARP) marker and tested on 103 commercial wheat cultivars derived from Zhou8425B. Cultivars with the resistance allele at the QPm.caas-3BS locus had averaged maximum disease severity reduced by 5.3%. This STARP marker can be used for marker-assisted selection in improvement of the level of powdery mildew resistance in wheat breeding.

     

N-Terminal Myristoylated VP5 is Required for Penetrating Cell Membrane and Promoting Infectivity in Aquareoviruses

正Dear Editor,Myristoylation is a naturally occurring post-translational modification for targeting cytoplasmic proteins to intracellular membranes.Unlike enveloped animal viruses,which enter host cells by membrane fusion,nonenveloped animal viruses must disrupt the cell membrane to initiate infection.Some animal viruses and several nonenveloped viruses such     

<Emphasis Type="Italic">Brevibacterium anseongense</Emphasis> sp. nov., isolated from soil of ginseng field

Gram-positive, aerobic, non-motile, pale-yellow, and rodshaped bacterium, designated as Gsoil 188^T, was isolated from the soil of a ginseng field in Pocheon, South Korea. A phylogenetic analysis based on 16S rRNA gene sequence comparison revealed that the strain formed a distinct lineage within the genus Brevibacterium and was most closely related to B. epidermidis NBRC 14811^T (98.4%), B. sediminis FXJ8.269^T (98.2%), B. avium NCFB 3055^T (98.1%), and B. oceani BBH7^T (98.1%), while it shared less than 98.1% identity with the other species of this genus. The DNA G + C content was 68.1 mol%. The predominant quinone was MK-8(H₂). The major fatty acids were anteiso-C_15:0 and anteiso-C_17:0. The cell wall peptidoglycan of strain Gsoil 188^T contained meso-diaminopimelic acid. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, and an unidentified aminolipid. The physiological and biochemical characteristics, low DNA-DNA relatedness values, and taxonomic analysis allowed the differentiation of strain Gsoil 188^T from the other recognized species of the genus Brevibacterium. Therefore, strain Gsoil 188^T represents a novel species of the genus Brevibacterium, for which the name Brevibacterium anseongense sp. nov. is proposed, with the type strain Gsoil 188^T (= KACC 19439^T = LMG 30331^T).