Maximum fluorescence and electron transport kinetics determined by light-induced fluorescence transients (LIFT) for photosynthesis phenotyping.

Abstract

Photosynthetic phenotyping requires quick characterization of dynamic traits when measuring large plant numbers in a fluctuating environment. Here, we evaluated the light-induced fluorescence transient (LIFT) method for its capacity to yield rapidly fluorometric parameters from 0.6 m distance. The close approximation of LIFT to conventional chlorophyll fluorescence (ChlF) parameters is shown under controlled conditions in spinach leaves and isolated thylakoids when electron transport was impaired by anoxic conditions or chemical inhibitors. The ChlF rise from minimum fluorescence (F o ) to maximum fluorescence induced by fast repetition rate (F m-FRR ) flashes was dominated by reduction of the primary electron acceptor in photosystem II (Q A ). The subsequent reoxidation of Q A - was quantified using the relaxation of ChlF in 0.65 ms (F r1 ) and 120 ms (F r2 ) phases. Reoxidation efficiency of Q A - (F r1 /F v , where F v = F m-FRR - F o ) decreased when electron transport was impaired, while quantum efficiency of photosystem II (F v /F m ) showed often no significant effect. ChlF relaxations of the LIFT were similar to an independent other method. Under increasing light intensities, F r2 '/F q ' (where F r2 ' and F q ' represent F r2 and F v in the light-adapted state, respectively) was hardly affected, whereas the operating efficiency of photosystem II (F q '/F m ') decreased due to non-photochemical quenching. F m-FRR was significantly lower than the ChlF maximum induced by multiple turnover (F m-MT ) flashes. However, the resulting F v /F m and F q '/F m ' from both flashes were highly correlated. The LIFT method complements F v /F m with information about efficiency of electron transport. Measurements in situ and from a distance facilitate application in high-throughput and automated phenotyping.

Plant phenotyping relevance

LIFT法を植物の光合成生理形質測定に適用し、従来のクロロフィル蛍光法との一致性を評価・検証しているため、植物フェノタイピング手法が中心です。

Code and data availability

The article describes LIFT/FL3000 chlorophyll fluorescence measurements on spinach leaves and thylakoids, but no public phenotype dataset, image/sensor data deposit, author analysis code, or trained model is mentioned. The only supplementary item is a 232 KB DOCX (likely figures/tables), with no stated data or code URL

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