Unravelling the different components of nonphotochemical quenching using a novel analytical pipeline.

Abstract

Photoprotection in plants includes processes collectively known as nonphotochemical quenching (NPQ), which quench excess excitation-energy in photosystem II. NPQ is triggered by acidification of the thylakoid lumen, which leads to PsbS-protein protonation and violaxanthin de-epoxidase activation, resulting in zeaxanthin accumulation. Despite extensive study, questions persist about the mechanisms of NPQ. We have set up a novel analytical pipeline to disentangle NPQ induction curves measured at many light intensities into a limited number of different kinetic components. To validate the method, we applied it to Chl-fluorescence measurements, which utilised the saturating-pulse methodology, on wild-type (wt) and zeaxanthin-lacking (npq1) Arabidopsis thaliana plants. NPQ induction curves in wt and npq1 can be explained by four components ( α , β , γ and δ ). The fastest two ( β and γ ) correlate with pH difference formed across the thylakoid membrane in wt and npq1. In wt, the slower component ( α ) appears to be due to the formation of zeaxanthin-related quenching whilst for npq1, this component is 'replaced' by a slower component ( δ ), which reflects a photoinhibition-like process that appears in the absence of zeaxanthin-induced quenching. Expanding this approach will allow the effects of mutations and other abiotic-stress factors to be directly probed by changes in these underlying components.

Plant phenotyping relevance

植物のクロロフィル蛍光によるNPQ誘導曲線から生理状態を抽出する新規解析パイプラインを開発し、植物試料で検証しているため、表現型取得・解析手法が中心です。

Code and data availability

The article describes a custom Python 3.9 multivariate analysis pipeline (PCA, FH-PhA, NMF) and NPQ induction datasets for wt and npq1 Arabidopsis, but no public deposit, availability statement, or authors' URL for the data or code is provided. The only URLs present (Hettich, Walz, Espressif, CC-BY license) are vendor/

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