Fluorescence lifetime of plant leaves with sub-nanosecond resolution

Abstract

Abstract The study aimed to develop a measurement apparatus for in vivo chlorophyll-a (Chl-a) fluorescence decay measurements of plants by means of time correlated single photon counting. In this approach, sub-nanosecond laser pulses with a repetition rate of 10 MHz are applied to excite the sample, followed by the analysis of arrival times of the emitted fluorescence photons. Photon statistics are generated by iteratively fitting the sum of two exponential functions. The tool was tested on both plastid and in vivo leaf samples of Savoy cabbage ( Brassica oleracea var. sabauda) with 3–4 subsequent leaves giving a complete sample coverage starting from the outermost. The Chl-a fluorescence lifetime exhibited a gradual increase in both the isolated plastid suspensions and the in vivo leaf samples towards the innermost leaf layers explained by an increase of natural absence of light (etiolation syndrome). Furthermore, cadmium stress and iron deficiency were investigated on treated sugar beet ( Beta vulgaris ) samples in vivo using TCSPS measurements. The reduced fluorescence quenching resulted in an increased fluorescence lifetime. Finally, a long-term (10 week) testing of the setup was carried out on Chl-retaining resurrection Haberlea rhodopensis plants protecting themselves by an elevated non-photochemical quenching yielding a decrease of fluorescence lifetime during their desiccation.

Plant phenotyping relevance

植物の生体クロロフィル蛍光寿命を測定する装置を開発し、複数の植物試料・ストレス条件・長期試験で検証しており、植物生理状態の取得法が研究の中心である。

Code and data availability

The paper reports TCSPC fluorescence lifetime measurements on Savoy cabbage, sugar beet, and Haberlea rhodopensis, but no public phenotype datasets, images, code, or models are deposited. The data availability statement states all data are included within the article (and any supplementary files), with no external URL.

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