Recent progress in genomics has promoted understanding of genetic mechanisms controlling complex crop production traits.In rice, yield is one of the most complex traits and generally determined by relationship between sink and source ability. While several quantitative trait locus (QTL) genes have been identified for sink-size traits, there has been little progress in genetic analysis for source ability. One of the reasons is that the source ability such as photosynthesis is a dynamic trait, hampering efforts to make precise measurements due to the technical difficulty involved in handling so many plants simultaneously. To facilitate genetic studies for source ability, we developed rapid and precise methods to evaluate leaf photosynthesis, one of the important factors for source ability in rice. QTL analysis using such methods successfully detected several promising QTLs and verified the potential utility of the evaluation methods. Our work reflects the importance of steady observation of rice plants in paddy fields and includes the application of the latest technology used in various areas of science to develop improved criteria for each trait toward advanced genetic studies.

抄録全体を表示

The chrysanthemum stunt viroid (CSVd) is a small, single-stranded, infectious RNA forming a circular secondary structure, which belongs to the Pospiviroidae family and mainly infects certain species and cultivars of Compositae and Solanaceae. The effects on cultivated chrysanthemum are severe, including stunting of plant height, reduced flower size, and flower color bleaching. However, the expression of the symptoms depends on the chrysanthemum cultivars. CSVd is known to be readily transmitted by sap, but the infection rate and incubation period were observed to differ according to the varieties. Some CSVd-resistant cultivars have also been reported and the resistance is heritable in crosses between a CSVd-resistant chrysanthemum cultivar and CSVd-susceptible cultivars.

抄録全体を表示

A torque-measuring device for measuring the engine output shaft on head-feeding combine harvesters was developed to investigate engine working load, an essential element in studies of fuel consumption and exhaust gas emissions. On most head-feeding combine harvesters, a pulley is fastened to an engine flywheel without a shaft. The power loss caused by the belt means engine torque should be measured between the flywheel and pulley. However, there is insufficient space to install conventional torque-measuring equipment. The torque-measuring device we developed was designed to be mounted between the flywheel and pulley. To make the device more compact, it was designed as a double-cylinder structure, with the deformation of the two torque-transmitting beams translated into a torque value. This device does not require irreversible alterations to be made to combines, and is designed to measure torque without any power loss. In static torque measurements, the margin of error of this device proved less than 6%, while the data measured during harvesting operations correlated with that of prior studies. Our results indicate that this device has good potential for use in further studies.

抄録全体を表示

Strains of Lactococcus lactis are present in various natural environment or fermented products, and have been used as starters. In this review, we firstly discuss the immunomodulatory effects of Lactococcus strains from the perspective of their strain-specificity. Forty-six different Lactococcus strains were investigated for their ability to induce cytokine production in the murine macrophage-like cell line, J774.1. Strain-specificity and heat stability related to the ability of Lactococcus cells to induce interleukin (IL)-6, IL-12 and TNF-α, and induce cell necrosis or apoptosis were discussed. Secondly, to examine the immunomodulatory effects of Lactococcus cells in vivo, the effects of oral administration of four strains were investigated for their ability to regulate IgE production in ovalbumin-sensitized mice. Among the four strains, only L. lactis strain C59 showed a significant reduction in the total IgE antibody levels in serum. This suppressive effect on IgE antibody production was lost when strain C59 was heat-killed. Experiments using splenocytes of mice administered with live strain C59 indicated that the suppression of IgE antibody production by live strain C59 was due to the suppression of IL-4 production. The strain-specific immunomodulatory effects of Lactococcus strains are discussed.

抄録全体を表示

The authors have been conducting research with the aim of developing methods to preserve and effectively use groundwater resources. This research has been ongoing since 2008 with the focus on Laura Island, Majuro Atoll, Republic of the Marshall Islands. Examination of the groundwater level potentials in pre-existing observation wells at Site No. 6, named by the United States Geological Survey (USGS), showed no difference in the groundwater level potential along the depth. Accordingly, observation well No. 6-N was established by boring to accurately observe the profiles of electric conductivity (EC) of groundwater. However, salt water intrusion occurred, contrary to the observed results for the groundwater level potential. Accordingly, the depth of the salt water intrusion was identified by developing a double packer, observation well No. 6-N was partially sealed and the sealing effect on the observation well was confirmed. This paper will discuss 1) the measures against salt water intrusion which occurred in the observation well, 2) the groundwater flow in an observation well, which was established to measure electric conductivity (EC) profiles of the groundwater, and 3) the depth of the groundwater path estimated by measuring EC profiles with a double packer in the observation well.

抄録全体を表示

We evaluated the effects of soil washing with ferric chloride (FeCl₃) on cadmium (Cd) concentrations in soil solutions and Cd absorption by two spinach cultivars in pot experiments. Soil samples were collected from washed and unwashed plots of rice paddy fields in Fukuoka and Toyama, Japan. Spinach pot cultivation was performed with the above mentioned soil under oxidative conditions. Before and after spinach cultivation, the Cd content in washed soils was always lower than that in unwashed soils.Soil washing with FeCl₃ affected the exchangeable cations (i.e. calcium increased and magnesium decreased). The Cd concentration in the soil solution from washed plot was lower than that in the solution from the unwashed plot throughout the spinach growth period, which was attributed to the exchangeable Cd content in both soils, because the fraction equilibrated with the Cd concentration in the soil solution. The exchangeable cation composition was affected by soil washing, but no significant difference in spinach yield was observed between the washed and unwashed plots. The leaf Cd concentration in the two spinach cultivars was up to 70% lower in the washed soils. This study suggested that soil washing in rice paddy fields with FeCl₃ was effective for controlling the Cd absorption risk of upland crops such as spinach. However, some risks remain to clear the CODEX standard (0.2 mg kg⁻¹) in the Cd content of leaf such as spinach, which has a high Cd absorptive capacity.

抄録全体を表示

The genetic diversity of Ralstonia solanacearum strains isolated from Zingiberaceae plants in the Asia-Pacific region was assessed by examining their biochemical properties, discriminating the phylogeny by polymerase chain reaction (PCR), and analyzing the egl and mutS gene sequences.These data were compared with those of reference strains covering the known diversity within the R. solanacearum species complex. Fifty-two of the Zingiberaceae plant isolates belong to either biovar 3 or biovar 4. Multiplex PCR analyses indicated that these strains belong to phylotype I. Phylogenetic analyses revealed that the investigated strains could be further divided into five or more groups and three major groups, based on the egl and mutS gene sequences, respectively. These groups were closely correlated with the host species and/or geographical origin. Our findings suggest that R. solanacearum strains affecting Zingiberaceae plants have multiple origins from within the Asia-Pacific region, and may have been disseminated with seed rhizomes.

抄録全体を表示

Recently, nine phylogenetic groups were proposed for a plurivorous fungus, Colletotrichum acutatum by some researchers. Some of them were named as C. simmondsii, C. fioriniae, C. acutatumsensu stricto and C. carthami based on morphology and phylogenetic analyses of β-tubulin-2 gene partial sequences. We re-identified 170 strains deposited as C. acutatum in the NIAS Genebank, Japan based on phylogenetic analysis with the β-tubulin-2 gene sequences. Eighty strains with reddish colony colors and relatively uniform conidia belonged to C. fioriniae, 37 with a grayish to yellowish color and short conidia to C. simmondsii, 25 with a blackish to cream color and short conidia to C. carthami, 12 with a cream to pale orange color and narrow conidia to ‘C. acutatum group A2-P’ newly designated in this paper, 5 with a brownish to orange color and larger conidia to C. acutatum group A4, and 11 to other species of Colletotrichum. No strain of C. acutatum s. str. was found. A dichotomous key to the member species and groups was designated based on reverse colony color and conidial morphology. Because pathogenic strains of 18 host plants were re-identified, updating of pathogen names was proposed. Ten of them should be changed to C. fioriniae, and the pathogens of each five host plants such as strawberry and apple should be replaced with 2 to 3 species or the group. Sweet pepper pathogen was tentatively classified into C. acutatum group A2-P.

抄録全体を表示

Bioethanol has great potential to reduce greenhouse gas emissions, improve energy security, and help revitalize agriculture. Accordingly, an E10 policy that substitutes bioethanol for 10% of all gasoline consumed will be globally popular. The present study aims to analyze the economic effects of bioethanol production for an E10 policy in nine ASEAN countries (except Brunei), with efforts to minimize CO₂ emissions. We consider two self-sufficient bioethanol production policies, i.e. self-sufficiency within each country and that within the ASEAN region under the scheme of a production quota. The optimization model, based on Takahashi et al.²⁰, and the inter-regional Input-Output Table, as estimated from the GTAP-7 (Global Trade Analysis Project, ver. 7) database, are used for consistent policy evaluation. The results demonstrated initially that the E10 policy under the scheme of a regional production quota elicited about 20% more environmental and economic effects than self-sufficient production within each country. Second, Singapore, Japan, China and the USA increased their production through bioethanol plant construction and annual production, even though this study assumed they did not increase bioethanol production. Approximately half the total induced production emerged in these countries. Third, induced production in agriculture accounted for half the total induced production. Based on these merits, several policy implications relating to the E10 policy with policy coordination are discussed.

抄録全体を表示

Although information about the hydrologic and ecological features of lowland evergreen forests in central Cambodia has been collected since the beginning of the 21st century, measurements of the transpiration process remain very limited. This paper describes the differences detected in transpiration (q) and crown-level stomatal conductance (G_S) between Calophyllum inophyllum (which undergoes successive leaf exchange) and Drypetes sp. (which performs irregular leaf exchange) (hereafter referred to as Calophyllum and Drypetes, respectively), and the analysis of these differences in consideration of their contrasting leaf phenologies. We evaluated q using sap flow measurements and obtained daily G_S values. Calophyllum and Drypetes had high and low periods between which q and G_S differed significantly. Within high/low periods, smaller scatter in the plot of G_S versus vapour pressure deficit (D) was found in Calophyllum compared to Drypetes. For a given value of D, q in high periods was 1.3 and 1.9 times larger than in low periods for Calophyllum and Drypetes, respectively. The smaller scatter for Calophyllum was the result of relatively constant physiological activity that was maintained by successive leaf fall.For both species, high periods were recorded after remarkable leaf-fall events; thus, our current data implied that leaf phenology is one of the most important factors affecting transpiration.

抄録全体を表示

In autumn 2009, the first outbreak of the shellfish-killing dinoflagellate Heterocapsa circularisquama bloom was recorded in a small lagoon, Lake Kamo, located on Sado Isl., Niigata Prefecture, Japan. At the time, the fisheries damage on the oyster culture due to the bloom was estimated at about JPY 190 million. Also in summer 2010, H. circularisquama formed a bloom in Lake Kamo, but in this case, no oyster kill was recorded. In the present study, we measured the temporal change in the abundance of viruses causing lysis of H. circularisquama and compared it with the host dynamics. We checked the host specificity and virus sensitivity of the isolated virus clones and host clones, respectively. Different types of host and virus clone dominantly coexisted in this lake, and the intraspecies host specificity of each HcRNAV clone isolated in Lake Kamo, 2010, agreed well with the host range predicted based on the deduced amino acid sequence of the major capsid protein (MCP). Considering the contemporary appearance of the host and virus, viral infection was assumed to be one of the factors affecting the dynamics of H. circularisquama population in this lake.

抄録全体を表示