Daisuke Takata

Identification and characterization of two novel genomic RNA segments of fig mosaic virus, RNA5 and RNA6

Fig mosaic virus (FMV), a negative-strand RNA virus, is recognized as a causal agent of fig mosaic disease. We performed RT-PCR for 14 FMV isolates collected from symptomatic fig plants in Japan and Serbia using primers corresponding to the conserved 13 nt stretches found at the termini of FMV genomic segments. The resulting simultaneous amplification of all FMV genomic segments yielded four previously identified segments of FMV and two novel segments. These novel FMV genomic RNA segments were found in each of the 14 FMV isolates analysed. In Northern blot studies, both the sense and antisense strands of these novel RNA molecules accumulated in FMV-infected fig leaves but not in uninfected fig leaves, confirming that they replicate as FMV genomic segments. Sequence analysis showed that the novel RNA segments are similar, in their structural organization and molecular evolutionary patterns, to those of known FMV genomic RNA segments. Our findings thus indicate that these newly discovered RNA segments are previously unidentified FMV genomic segments, which we have designated RNA5 and RNA6.

Distribution of Radiocesium from the Radioactive Fallout in Fruit Trees

We report the impact of radiocesium released by the Fukushima Daiichi nuclear power plant accident on fruit trees in the vicinity. Specifically, we discuss our findings related to the absorption and translocation of radiocesium in peach (Prunus persica L. Batsch) trees because peaches are a major crop in Fukushima Prefecture.

Radiocesium transfer into the fruit of deciduous fruit trees contaminated during dormancy

Abstract Following the accident at the Tokyo Electric Power Company, Fukushima Daiichi Nuclear Power Plant (FDNPP), radiocesium (134Cs + 137Cs) concentrations in deciduous mature fruits were determined in orchards in the northern area of Fukushima Prefecture. At the time of the nuclear accident, most deciduous fruit trees were in the dormant stage prior to bud burst. To evaluate the relationship between radiocesium deposition in the soil and fruit contamination, radiocesium concentrations were measured from the 5-cm topsoil and from six fruit species across 17 orchards in 2011. The vertical distribution of radiocesium in the topsoil (0–30 cm in depth) and its spatial distribution in the 5-cm topsoil underlying the tree canopy of a peach, Prunus persica (L.) Batsh, orchard (“Akatsuki” cultivar) were also investigated. Significant correlations between the radiocesium concentration in the mature fruit and that in the 5-cm topsoil layer were observed for the 17 orchards as well as for the trees of the peach orchard. However, 93% of the 137Cs found in the 30-cm soil core was retained within the top 3 cm of the soil in the peach orchard. Considering the profile of the root of this deciduous fruit tree, we assumed a negligible level of radiocesium uptake via the roots. However, the possibility of inward migration via the bark was undeniable, because some radiocesium adhered to the tree canopy before bud burst while depositing on the soil surface. Additionally, transfer factors for peach and grape, hybrid of Vitis labrusca L. and Vitis vinifera L., from young, uncontaminated trees cultivated with contaminated soil were lower than those previously reported.

Online Monitoring System on Controlled Irrigation Experiment for Export Quality Mango in Thailand

Export quality fresh mango fruit requires a careful management from production to distribution in order to meet a high standard specifically for a long supply chain. In this paper, we describe our online monitoring system to observe responses of mango trees to different levels of irrigation intensities, based on which an optimal irrigation regime can be established. The system consists of different sensors for soil moisture content, sap-flow, photographs, and so on. To fully control the amount of water irrigated, rain-out shelter was installed for every tree for the experiment. Field observation data are used to compute water consumption and water stress of target trees. Preliminary results supported the practicality of this system that can further be used for quantitative assessment and numerical simulation for optimizing a production system aiming at a long supply chain.

Translocation of Radiocesium in Fruit Trees

We report our findings on the translocation and distribution of radiocesium inside fruit trees after radiocesium (Cs) was released by the accident at the Fukushima Daiichi Nuclear Power Plant.