Use of NaCN to increase the growth of N2-fixing bacteria in a model spermosphere mimicked by sucrose and amino acids leached by seeds

In order to study the establishment of a spermosphere, the C₂H₂ reduction activity of N₂-fixing bacteria isolated from river sand was examined in a simulated spermosphere in the river sand which contained sucrose, an amino acid mixture, and CN^- released from plant seeds. The sand incubated with 10^-10 to 10^-9 mol CN^- 30 g sand^-1 exhibited higher C₂H₂ reduction activity than that without CN^-. The change in the most probable number of N₂ fixers with increasing quantities of CN^- roughly corresponded to that in C₂H₂ reduction activity. However, the most probable number of non-N₂-fixing bacteria decreased except for CN^--tolerant ones. Both C₂H₂ reduction activity and proliferation of the N₂ fixers isolated on a modified Burk's medium were almost similar to those in the bacteria in the sand. In contrast, the proliferation of some nonfixers decreased with an increasing CN^- concentration. C₂H₂ reduction activity of N₂ fixers cultured in combination with non-fixers exhibited a clear peak at 10^-7 M CN^- as for C₂H₂ reduction activity in the sand. We therefore speculate that cyanide evolved from seeds during a pregermination period may suppress the growth of general bacteria, but may promote the proliferation of N₂ fixers, thus contributing to the establishment of a spermosphere.     

Chemical kinetics of Japanese cedar,cypress, fir,and spruce and characterization of charcoal

 Thermogravimetric and differential thermal analyses techniques have been applied to investigate the thermal degradation characteristics and chemical kinetics of Japanese cedar, cypress, fir, and spruce. The decomposition of the components could be modeled by an Arrhenius kinetic expression. The kinetic parameters were extracted from the thermogravimetric data using least-squares techniques. The heating rates used for the analyses were 10°, 5°, and 0.33°C/min; and the activation energy and reaction order of the above woods were 7.54, 8.39, 2.87, and 7.88 kJ/mol and 0.71, 0.64, 0.44, and 0.63, respectively. Finally, carbonization was done to produce charcoal from these woods under various operating conditions, and the charcoal was characterized in respect to yield, heating value, electrical conductivity, and X-ray diffraction. The quality of the charcoal from fir was the best among the four types of wood. The charcoal produced is inferior to binchotan (white charcoal) in respect to electrical conductivity and crystalline structure. Received: February 13, 2002 / Accepted: July 12, 2002 Acknowledgment The authors express their gratitude to Professor Yoshida of Applied Chemistry in Tokyo Metropolitan University for performing the TG/DTA in his laboratory and for his valuable suggestions about the analyses.     

Multilocus phylogenetic analysis revealed a new cryptic lineage of Serpula himantioides in Japan

Serpula himantioides is a widely distributed saprotrophic fungus that causes root and butt rot in various tree species. In Japan, butt rot associated with S. himantioides is observed in Chamaecyparis pisifera and Abies sachalinensis. Previous studies have shown that S. himantioides includes five phylogenetically defined cryptic lineages, but the placement of Japanese isolates remains unclear. To clarify the phylogenetic relationship between Japanese S. himantioides and the five known lineages, we conducted a phylogenetic analysis using three newly collected Japanese isolates along with 74 S. himantioides isolates, based on the internal transcribed spacer (ITS) region, the 28 S large subunit (LSU) rDNA, the beta-tubulin (tub) gene, and the heat stress protein (hsp) gene. The concatenated phylogenetic tree showed that Japanese isolates composed a clade with a high bootstrap value distinct from the known lineages, indicating the Japanese isolates present a new cryptic lineage of S. himantioides.     

Considering biology when inferring range-limiting stress mechanisms for agricultural pests: a case study of the beet armyworm

Reliable niche models are a cornerstone of pest risk analyses, informing biosecurity policies and the management of biological invasions. Because species can invade and establish in areas with climates that are different from those that are found in their native range, it is important to accurately capture the range-limiting mechanisms in models that project climate suitability. We examined a published niche model for the beet armyworm, Spodoptera exigua, to assess its suitability for bioeconomic analyses of its pest threat, and identified issues with the model that rendered it unreliable for this purpose. Consequently, we refitted the CLIMEX model, paying close attention to the biology underpinning the stress mechanisms. This highlighted the necessity of carefully considering how the different stress mechanisms operate, and to select mechanisms which align with knowledge on the species’ biology. We also identified the important role of irrigation in modifying habitat suitability. The refitted model accords with both distribution data and our understanding of the biology of this species, including its seasonal range dynamics. The new model identifies establishment risks to South America, Africa, the Middle East and Asia, and highlights that under current climate, Europe is only climatically suitable during warm seasons when crops are available. The modelling exercise reinforced the importance of understanding the meaning of a location record (e.g. persistent versus ephemeral populations) and of carefully exploring the role of habitat-modifying factors, such as irrigation, in allowing species to persist in otherwise inclement localities.     

Seven-year changes in growth and crown shape of Thujopsis dolabrata var. hondai saplings after release from suppression

We investigated changes in sapling growth and morphology of Thujopsis dolabrata var. hondai (hiba) for 7 years after release from suppressed lighting by selection cutting. We examined changes in aboveground biomass, elongation of stems and lateral branches, and annual diameter increment at the stem base. Vertical distributions of leaves per branch and per individual were also measured for morphological analysis. Under the suppressed condition before cutting, the crown consisted of orthotropic lateral branches, elongating up to the top of the stem or farther, and no branch was aborted. This crown type with large crown depth and concavity of the upper part had a bowl-like appearance. After the selection cutting, relative light intensity on the saplings increased from 4% to 26%. The increment enhanced aboveground biomass and stem elongation 7 years after the cutting. Diameter growth at the stem base was particularly accelerated 2 years after the cutting. While crown shape transformation of the saplings was not conspicuous at 7 years after the cutting, some released saplings showed a superior stem elongation ratio to that of the lateral branches. Thus, the upper part of the crown of these saplings changed from a bowl-like shape to a convex shape like that of a dome. Our study suggested that suppressed hiba saplings with the unique bowl-shaped crown enhanced their growth rates rapidly in response to improved light conditions, but required much more than 7 years for the full process of crown transformation for us to identify future trees in this stand. An erratum to this article is available at.     

Brown root rot of trees caused by Phellinus noxius in the Ryukyu Islands,subtropical areas of Japan

The fungus Phellinus noxius has a broad host range and causes brown root rot in a variety of tree species of various ages, irrespective of their original health. The fungus is widely distributed in tropical countries of Southeast Asia, the Pacific Islands and Australia, Central America and Caribbean, and Africa. Since 1988, when brown root rot was first found on Ishigaki Island, Okinawa Prefecture, the disease has been reported on several islands in Okinawa and Kagoshima Prefectures, and it has been causing serious problems to shade, windbreak, ornamental and landscape trees in the Ryukyu Islands, located in the subtropical region of southern Japan. Here, we report on the current status of P. noxius‐caused brown root rot in the Ryukyu Islands, Japan, including symptoms, occurrence, dispersal, distribution and host tree species of the disease, pathogenicity and/or virulence of the pathogen, and disease management based on our surveys and previously published reports from Japan. Brown root rot has been confirmed in 53 tree species from 32 plant families at different sites on 10 of the 12 islands surveyed. Among the 53 tree species, 34 were first recorded in Japan as host plants of P. noxius. The disease occurs mainly in shade, ornamental and windbreak trees at sightseeing places, parks, roadsides, agricultural land such as sugar cane fields, and around residences or other places associated with human activities.     

Spatial analysis of genetic diversity in a comprehensive collection of the native grass Bromus auleticus Trinius (ex Nees) in Uruguay

Bromus auleticus Trinius (ex Nees) is a perennial allogamous C3 grass native to the Campos grasslands. It has potential to play a key role in restoration of both abandoned agricultural and overgrazed lands. We aim to reveal the existence of local adaptation and to assess whether phenotypes could be differentiated in relation to their ecogeographic region of origin. Previous reports estimated significant levels of variability among and within populations, but as yet there is no evidence of local adaptation and phenotypic relations with ecogeographic regions for this species. Indeed, there is a lack of knowledge about the spatial distribution of diversity, which limits the possibilities of using B. auleticus in ecological restoration and plant breeding. A comprehensive collection of 82 accessions of B. auleticus from eight ecogeographic regions within Uruguay was used to characterize diversity by measuring phenologic, morphologic, productive and reproductive traits. We found high diversity among B. auleticus accessions, and the spatial distribution of this diversity follows a pattern accounted by ecogeographic regions to a large extent. Our results also indicate large genotype × environment interaction, confirming local adaptation. Phenotypic values permitted, with a 3.7% error rate, discrimination of accessions according to their ecogeographic region of origin, suggesting the existence of differentiated ecotypes. We consider that the diversity observed should be conserved and used for breeding cultivars of this species and for the restoration of degraded grasslands by considering ecogeographic regions when selecting seed sources.     

Towards the partial resumption of agriculture with buckwheat cultivation in fields physically decontaminated of radioactive cesium after the nuclear power plant accident in 2011: a case study in Yamakiya District,Fukushima

ABSTRACT

Yamakiya District in the town of Kawamata, Fukushima Prefecture, was evacuated after the nuclear accident at the Tokyo Electric Power Company’s Fukushima Dai-ichi nuclear power plant in 2011. Since then, nuclear decontamination procedures have been applied to the surrounding environment, including agricultural fields. The decontamination procedure for agricultural fields consists of the removal of radiation-contaminated surface soil, followed by soil dressing and plowing. However, radioactive cesium (RCs) remains in the soil even after decontamination. In this study, we investigated the effect of applying nitrogen, potassium fertilizers, and cattle manure compost on buckwheat growth and the concentration of RCs in the grain of buckwheat cultivated in a decontaminated field from 2014 to 2016. Applications of potassium fertilizer and cattle manure compost increased the soil exchangeable potassium content and decreased the RCs concentration in the grain of buckwheat cultivated in the decontaminated field. Before the cultivation of the first buckwheat crop, the RCs concentration in soil varied widely and there were ‘hot spots’ with high RCs concentrations because of insufficient mixing of the original and the dressed soils. Therefore, soil had to be adequately mixed to avoid producing grain with a high RCs concentration. Buckwheat grew better when supplied with more nitrogen fertilizer than the conventional amount at the first cultivation, indicating that the dressed soil had low fertility. We also monitored buckwheat cultivation by local farmers in decontaminated fields from 2015 to 2017. By using potassium fertilizer, the farmers produced buckwheat grain with low RCs concentrations from 2015 to 2017.     

Confirming a major QTL and finding additional loci responsible for field resistance to brown spot (Bipolaris oryzae) in rice

Brown spot is a devastating rice disease. Quantitative resistance has been observed in local varieties (e.g., ‘Tadukan’), but no economically useful resistant variety has been bred. Using quantitative trait locus (QTL) analysis of recombinant inbred lines (RILs) from ‘Tadukan’ (resistant) × ‘Hinohikari’ (susceptible), we previously found three QTLs (qBS2, qBS9, and qBS11) that conferred resistance in seedlings in a greenhouse. To confirm their effect, the parents and later generations of RILs were transplanted into paddy fields where brown spot severely occurred. Three new resistance QTLs (qBSfR1, qBSfR4, and qBSfR11) were detected on chromosomes 1, 4, and 11, respectively. The ‘Tadukan’ alleles at qBSfR1 and qBSfR11 and the ‘Hinohikari’ allele at qBSfR4 increased resistance. The major QTL qBSfR11 coincided with qBS11 from the previous study, whereas qBSfR1 and qBSfR4 were new but neither qBS2 nor qBS9 were detected. To verify the qBSfR1 and qBSfR11 ‘Tadukan’ resistance alleles, near-isogenic lines (NILs) with one or both QTLs in a susceptible background (‘Koshihikari’) were evaluated under field conditions. NILs with qBSfR11 acquired significant field resistance; those with qBSfR1 did not. This confirms the effectiveness of qBSfR11. Genetic markers flanking qBSfR11 will be powerful tools for marker-assisted selection to improve brown spot resistance.     

Field trial of salad oil application for the induction of male flower browning ofCryptomeria japonica

A field trial of salad oil application for the induction of male flower browning ofCryptomeria japonica was conducted. The browning effect of salad oil applied from a helicopter was found to vary from clone to clone depending on the earliness of male flower development. When applied at the flower initiation stage, salad oil turned male flowers to a brown color; when applied later, the browning effect of salad oil was not clear. The effectiveness of the application depended on how close to the time of flower initiation it occurred. The harmful changes caused by salad oil solution were only observed on the leaves of Japanese plume-grass (Miscanthus sinensis), and no other effects on other plants were observed. Todd Davies for his warm hearted advice on English composition.