Biology subjects

Shiojiri, K.

Publications and source records attributed to Shiojiri, K..

4 recordsLinked to original sources

bioRxiv2026

Recurring daytime and nighttime modes of VOC emissions in a cool-temperate oak forest

Plants emit substantial amounts of biogenic volatile organic compounds (VOCs) that link plant physiological activity to ecological interactions and atmospheric chemistry. However, the processes regulating VOC emissions within the forest air and at the interface directly above the canopy remain poorly characterized. In this study, we investigated forest-scale VOC dynamics in a cool-temperate deciduous forest dominated by Quercus crispula using high-time- and high-mass-resolution proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) integrated with positive matrix factorization (PMF). This non-targeted, process-oriented framework was applied to forest-interior and canopy-top atmospheres during rain-free summer days in 2024 and 2025 to extract dominant modes of VOC emissions. The PMF consistently resolved two recurring modes characterized by the daytime and nighttime enhancement patterns. The daytime mode was dominated by isoprene and its oxidation products and demonstrated strong light- and temperature-dependence, whereas the nighttime mode was enriched in mono- and sesquiterpenes. The daytime contribution exhibited a pronounced morning-afternoon asymmetry, indicating non-linear physiological and canopy-scale controls. These patterns were reproducible across the years. This study demonstrates that combining PTR-ToF-MS with PMF enables robust, top-down identification of recurring modes of forest VOC variability within and above forest canopies, linking leaf-level physiology and ecosystem-scale atmospheric exchange. HighlightForest-scale VOC emissions were resolved into recurring daytime and nighttime modes using a non-targeted PTR-ToF-MS and PMF framework.

physiology↗

bioRxiv2025

Contrasting ecological communities in rice paddy fields under conventional and no-fertilizer farming practices

Global crop production is essential for providing energy and nutrients to humans, but agricultural systems contribute substantially to environmental issues, making it crucial to find sustainable methods for crop production. In this study, we conducted extensive field monitoring of two rice paddy fields in Kyoto Prefecture, Japan, where a rice variety, Hinohikari, was cultivated to investigate how ecological communities influence rice growth and yields under two contrasting farming practices: conventional farming and no-fertilizer farming. We had three objectives: (1) to monitor rice growth and ecological dynamics to create a comprehensive ecological time series using quantitative environmental DNA metabarcoding and complementary monitoring methods, (2) to identify ecological variables that causally affect rice performance using nonlinear time series analysis, and (3) to examine the effects of the two farming practices on ecological variables and rice performance. As expected, the no-fertilizer paddy field showed lower rice growth and yields but still produced 40-50% of the yields of the conventional field. Ecological monitoring revealed contrasting ecological communities between the two fields, particularly among plant species on the paddy ridges and microbial taxa. Twenty-five taxa had statistically clear causal influences on rice performance. While the per-abundance influences of the causal taxa were largely similar in both paddy fields, their abundances were different, contributing to the differences in the overall effects of these taxa on the rice performance. These findings suggest that the abundance of causal taxa, along with nutrient conditions, may have driven differences in rice growth between the two paddy fields.

ecology↗

bioRxiv2022

Evolutionary relations between mycorrhizal symbiosis and plant-plant communication in trees

Ecological factors that drive the evolution of plant-plant communication via volatile organic compounds (VOCs) have not been elucidated. Here, we examined the relationship between type of mycorrhizal symbiosis (arbuscular mycorrhiza, AM; ectomycorrhizal mycorrhiza, ECM) and plant-plant communication within tree species. We hypothesized that ECM promotes plant-plant communication among conspecific individuals in trees, because it promotes their cooccurrence through positive plant-soil feedback. We tested communication using saplings of nine tree species with either AM or ECM, either exposed for 10 days to volatiles from an injured conspecific or not exposed. We evaluated the number of insect-damaged leaves and the area of leaf damage after 1 and 2 months in the field. Most exposed ECM-associated trees had less leaf damage than controls. However, AM-associated trees did not differ in leaf damage between treatments. We combined our results with those of previous studies and analysed the evolutionary relation between mycorrhizal type and the presence or absence of plant-plant communication within tree species. ECM symbiosis is associated with the evolution of plant-plant communication within species. These results suggest that the evolution of types of mycorrhizal symbiosis associates with the evolution of plant-plant communications within tree species.

ecology↗

bioRxiv2018

Occurrence of diamondback moths Plutella xylostella and their parasitoid wasps Cotesia vestalis in mizuna greenhouses and their surrounding areas

We observed the seasonal occurrence of diamondback moth (DBM) larvae, Plutella xylostella (Lepidoptera: Plutellidae), and their native parasitoid wasps, Cotesia vestalis (Hymenoptera: Braconidae), on mizuna plants, Brassica rapa var. laciniifolia (Brassicales: Brassicaceae), in three commercial greenhouses and on wild cruciferous weeds, Rorippa indica (Brassicales: Brassicaceae), in the surrounding area in the Miyama countryside in Kyoto, Japan. The occurrences of DBM larvae in greenhouses followed their occurrence in the surrounding area: however, some occurrences of DBM in greenhouses took place when the DBM population in the surrounding was rather low. This suggests that the occurrence of DBM in greenhouses cannot always be explained by its seasonal occurrence in the surrounding areas. The occurrence of C. vestalis followed that of DBM larvae in mizuna greenhouses and in the surrounding areas. No C. vestalis were recorded in greenhouses when DBM was not present. Cotesia vestalis females preferred volatiles emitted from DBM-infested mizuna plants to those from uninfested conspecifics under laboratory conditions. Natural HIPVs (herbivory-induced plant volatiles) emitted from DBM-infested mizuna plants in greenhouses probably attracted C. vestalis from the surrounding area to cause their co-occurrence.

ecology↗