Practical phytoextraction in cadmium-polluted paddy fields using a high cadmium accumulating rice plant cultured by early drainage of irrigation water

Some indica rice varieties are potential phytoextractors for paddy fields polluted with Cd because of their high biomass and because they can accumulate Cd to moderate levels in their shoots. To establish a practical phytoextraction system, phytoextraction using two indica rice cultivars (MORETSU and IR-8) was carried out in a paddy field polluted with moderate Cd levels (2.91 and 2.52 mg kg⁻¹, respectively). The Cd concentration and Cd uptake of MORETSU increased when irrigation water was drained at the maximum tillering stage, and the paddy soil was under oxidative conditions until harvesting. The Cd uptake of MORETSU and IR-8 increased and reached 516 and 657 g ha⁻¹, respectively, at the beginning of October. After phytoextraction using these high Cd accumulating rice varieties for 2 years, the Cd concentration in the paddy field decreased by 18% compared with the initial Cd concentration. The Cd concentration in the rice grains of a japonica ordinary rice variety (HINOHIKARI) subsequently grown on the field after the phytoextraction was lower than the concentration in rice grown on a non-phytoextracted field. These results suggest that phytoextraction using high Cd accumulating rice varieties with early drainage of irrigation water is a practical remediation system for moderate Cd polluted paddy fields in southwest Japan.     

The first occurrence of leaf mold of tomato caused by races 4.9 and 4.9.11 of <Emphasis Type="Italic">Passalora fulva</Emphasis> (syn. <Emphasis Type="Italic">Fulvia fulva</Emphasis>) in Japan

Tomato leaf mold caused by Passalora fulva was found on two tomato varieties carrying the Cf-9 gene in Japan, in 2007. The isolates obtained from Chiba and Fukushima were identified as race 4.9.11, and those from Gunma were races 4.9 or 4.9.11. This is the first report in Japan of tomato leaf mold caused by P. fulva strains that can overcome the Cf-9 gene.     

Effect of temperature on survival,growth and malformation of cultured larvae and juveniles of the seven-band grouper Epinephelus septemfasciatus

The effects of rearing temperature (23–29 °C) during the larval and juvenile stage on survival, growth and skeletal malformations in the seven-band grouper Epinephelus septemfasciatus were investigated. The survival rate of juveniles 30–40 mm in total length emerging from eggs was higher at 25 and 26 °C (0.1–1.3 %) than at 23 °C or 27–29 °C (0.004–1.5 %). Growth (increase in total length) was accelerated at higher temperatures. The frequency of malformed individuals was lower at 25–27 °C (36.0–61.5 %) than at 23, 28 or 29 °C (65.3–76.9 %). Specific incidences of spinal curvature and centrum fusion or defects in juveniles were not related to rearing temperature. However, incidences of twisted or compressed vertebrae (6.5–64.0 %) were higher at higher temperatures, while the incidence of bifurcated neural spine was significantly higher at 23 °C (43.6–54.4 %) than at other temperatures (3.3–22.7 %). The incidence rate of spinal curvature (23.3 %) was significantly higher in juveniles with a deflated swim bladder, regardless of rearing temperature. The results of this study suggest that the optimum culture temperature for seven-band grouper is 25–26 °C, collectively considering the survival, growth and incidences of abnormalities. Our results also demonstrate the significance of identifying the conditions for swim bladder inflation to prevent spinal curvature in seven-band grouper.     

Development of an on-site plum pox virus detection kit based on immunochromatography

Sharka disease, caused by plum pox virus (PPV), is the most serious viral disease of stone fruit trees. Among the eight known strains of the virus, PPV-D is the most important due to its recent global spread. Although enzyme-linked immunosorbent assay (ELISA) is the most common approach for diagnosing sharka, it involves time-consuming steps and requires expensive equipment and trained technicians. In this study, an on-site PPV detection kit based on immunochromatography was developed using polyclonal antibodies against the coat protein (CP) of a PPV-D isolate. The immunochromatographic (IC) assay kit was as sensitive as a commercial ELISA system for detecting Japanese PPV-D isolates. Moreover, it was easy to use (a one-step procedure), and results could be obtained on-site within 15 min without special laboratory equipment. The IC assay kit detected the virus from every aerial part of symptomatic Japanese apricot trees. In a detailed study of viral localization in leaves, the most suitable plant parts for use in the IC assay were symptomatic mesophyll tissues and the region from the petiole to the main vein. A positive reaction was also observed using the CP of other major (PPV-M and PPV-Rec) and minor (PPV-EA, PPV-W, and PPV-T) strains.     

Antiangiogenic activity of brown algae fucoxanthin and its deacetylated product, fucoxanthinol

The antiangiogenic effects of fucoxanthin and a deacetylated product, fucoxanthinol, were examined. Fucoxanthin significantly suppressed HUVEC proliferation and tube formation at more than 10 microM, but it had no significant effect on HUVEC chemotaxis. The formation of blood vessel-like structures from CD31-positive cells was evaluated using embryonic stem cell-derived embryoid bodies. Fucoxanthin effectively suppressed the development of these structures at 10-20 microM, suggesting that it could suppress differentiation of endothelial progenitor cells into endothelial cells involving new blood vessel formation. Fucoxanthin and fucoxanthinol suppressed microvessel outgrowth in an ex vivo angiogenesis assay using a rat aortic ring, in a dose-dependent manner. These results imply that fucoxanthin having antiangiogenic activity might be useful in preventing angiogenesis-related diseases.     

Infection by Magnaporthe oryzae chrysovirus 1 strain A triggers reduced virulence and pathogenic race conversion of its host fungus, <Emphasis Type="Italic">Magnaporthe oryzae</Emphasis>

Magnaporthe oryzae chrysovirus 1 strain A (MoCV1-A) is associated with an impaired growth phenotype of its host fungus, Magnaporthe oryzae. In this report, we assayed the virulence and pathogenicity of MoCV1-A-infected and MoCV1-A-free M. oryzae on rice plants. MoCV1-A infection did not affect virulence-associated fungal traits, such as conidial germination and appressorium formation. However, after punch inoculation of leaves on rice plants, MoCV1-A-infected strain formed smaller lesions than the MoCV1-A-free strain did on all rice varieties tested, showing that MoCV1-A infection resulted in reduced virulence of host fungi in rice plants. In contrast, after spray inoculation of rice seedlings, in some cases, MoCV1-A-infected and MoCV1-A-free strains caused different lesion types (resistance to susceptible, or vice versa) on individual international differential rice varieties. However, we did not find any gain/loss of the fungal avirulence genes by PCR, suggesting that MoCV1-A infection can convert the pathogenicity of the host M. oryzae from avirulence to virulence, or from virulence to avirulence, depending on the rice variety. We also confirmed the correlation of these race conversion events and invasive hyphae growth of the fungi in a leaf sheath inoculation assay. These data suggested that MoCV1-A infection generally confers hypovirulence to the fungal host and could be a driving force to generate physiological diversity, including pathogenic races.     

Recent races of spinach downy mildew pathogen <Emphasis Type="Italic">Peronospora farinosa</Emphasis> f. sp. <Emphasis Type="Italic">spinaciae</Emphasis> in Japan

Isolates of spinach downy mildew fungus, Peronospora farinosa f. sp. spinaciae, collected at seven sites in Japan from December 2013 to March 2016, were identified as belonging to races 8, 10, 12 and 13, and one was unauthorized. Races 10, 12, 13 and the unauthorized were first found in Japan.     

Stand-scale transpiration estimates in a Moso bamboo forest: (I) Applicability of sap flux measurements

The applicability of sap flux (F_d) measurements to bamboo forests has not been studied. This study was undertaken to establish an optimal and effective design for stand-scale transpiration (E) estimates in a Moso bamboo forest. To this aim, we validated F_d measurements in Moso bamboos in a cut bamboo experiment. In addition, we analyzed how sample sizes affect the reliability of E estimates calculated from F_d and conducting culm area (A_{S_b}). In the cut bamboo experiments, we found that F_d measurement using a 10 mm probe was a valid means of determining the water-use behavior of a Moso bamboo, although a specific correction was needed. Furthermore, we calculated E from stand A_{S_b} (A_{S_stand}) and mean stand F_d (J_S). Employing Monte Carlo analysis, we examined potential errors associated with sample size in E, A_{S_stand}, and J_S using an original dataset with A_{S_b} and F_d measured for 40 and 16 individuals, respectively. Consequently, we determined the optimal sample size for both A_{S_stand} and J_S estimates as 11. The optimal sample sizes for J_S were almost the same under different vapor pressure deficit and soil moisture conditions. The optimal sample size for J_S at the study site was less than that of a coniferous plantation in the same region probably owing to small individual-to-individual variations in sap flux in the Moso bamboo forest. Our study concludes that sap flux measurements are an applicable technique for assessing water use in Moso bamboo forests.