Biology subjects

Kanazawa, A.

Publications and source records attributed to Kanazawa, A..

3 recordsLinked to original sources

bioRxiv2024

From Quantitative Trait Loci towards Mechanisms: Linkage Integration Hypothesis Testing (LIgHT) Sheds Light on the Mechanisms of Genetically Modulated Stress Tolerance

The goal of this work is to assess the mechanistic bases of natural genetic variations in plant responses of photosynthesis to stress. To achieve this goal, we devised the Linkage Integration Hypothesis Testing (LIgHT) approach, comparing chromosomal locations of quantitative trait loci (QTL) for multiple phenotypes to distinguish between hypothetical mechanisms. As a use case, we explored genetic variations in photosynthesis-related processes under chilling stress in recombinant inbred lines of cowpea (Vigna unguiculata L. Walp.). We focused on photosynthesis-related parameters measurable in high throughput and indicative of proposed chilling responses, including the states of photosystems I (PSI) and II (PSII), photoprotective nonphotochemical quenching, PSII photodamage, and nyctinastic leaf movements (NLM). The patterns of QTL linkages indicated chilling stress tolerance is genetically controlled by avoiding PSII photodamage rather than PSI damage or NLM. This model was validated in a separate experiment measuring the rates of PSII photodamage and repair. Additional linkages suggest that chilling-induced damage to PSII is controlled by the thylakoid proton motive force and redox state of PSII. This regulation is modulated by thylakoid fatty acid composition, as suggested in Hoh et al., 2022. We propose the LIgHT approach can be broadly applied to test mechanisms underlying genetic variations. HighlightThis work Introduces the Linkage Integration Hypothesis Testing (LIgHT) approach for mechanistic studies of natural variations, identifying photosynthetic regulatory mechanisms underlying natural variations to abiotic stresses by applying this approach.

plant biology↗

bioRxiv2021

Light Potentials of Photosynthetic Energy Storage in the Field: What limits the ability to use or dissipate rapidly increased light energy?

The responses of plant photosynthesis to rapid fluctuations in environmental conditions are thought to be critical for efficient capture of light energy. Such responses are not well represented under laboratory conditions, but have also been difficult to probe in complex field environments. We demonstrate an open science approach to this problem that combines multifaceted measurements of photosynthesis and environmental conditions, and an unsupervised statistical clustering approach. In a selected set of data on mint (Mentha sp.), we show that the "light potential" for increasing linear electron flow (LEF) and nonphotochemical quenching (NPQ) upon rapid light increases are strongly suppressed in leaves previously exposed to low ambient PAR or low leaf temperatures, factors that can act both independently and cooperatively. Further analyses allowed us to test specific mechanisms. With decreasing leaf temperature or PAR, limitations to photosynthesis during high light fluctuations shifted from rapidly-induced NPQ to photosynthetic control (PCON) of electron flow at the cytochrome b6f complex. At low temperatures, high light induced lumen acidification, but did not induce NPQ, leading to accumulation of reduced electron transfer intermediates, a situation likely to induce photodamage, and represents a potential target for improving the efficiency and robustness of photosynthesis. Finally, we discuss the implications of the approach for open science efforts to understand and improve crop productivity.

plant biology↗

bioRxiv2019

Charting the native architecture of thylakoid membranes with single-molecule precision

Thylakoid membranes scaffold an assortment of large protein complexes that work together to harness the energy of light to produce oxygen, NADPH, and ATP. It has been a longstanding challenge to visualize how the intricate thylakoid network organizes these protein complexes to finely tune the photosynthetic reactions. Using cryo-electron tomography to analyze membrane surface topology, we have mapped the native molecular landscape of thylakoid membranes within green algae cells. Our tomograms provide insights into the molecular forces that drive thylakoid stacking and reveal that photosystems I and II are strictly segregated at the borders between appressed and non-appressed membrane domains. This new approach to charting thylakoid topology lays the foundation for dissecting photosynthetic regulation at the level of single protein complexes within the cell.

plant biology↗