Analysis of the changes of electron transfer and heterogeneity of photosystem II in Deg1-reduced Arabidopsis plants

Xiaogang Wen; Zhipan Yang; Shunhua Ding; Huixia Yang; Lixin Zhang; Congming Lu; Qingtao Lu

doi:10.1007/s11120-021-00842-2

Analysis of the changes of electron transfer and heterogeneity of photosystem II in Deg1-reduced Arabidopsis plants

Photosynth Res. 2021 Dec;150(1-3):159-177. doi: 10.1007/s11120-021-00842-2. Epub 2021 May 16.

Authors

Xiaogang Wen^{1

2}, Zhipan Yang¹, Shunhua Ding¹, Huixia Yang¹, Lixin Zhang³, Congming Lu⁴, Qingtao Lu⁵

Affiliations

¹ Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
² Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100093, China.
³ State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, 85 Minglun Street, Kaifeng, 475001, China.
⁴ State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China. cmlu@sdau.edu.cn.
⁵ Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China. lu_qingtao@ibcas.ac.cn.

PMID: 33993381
DOI: 10.1007/s11120-021-00842-2

Abstract

Deg1 protease functions in protease and chaperone of PSII complex components, but few works were performed to study the effects of Deg1 on electron transport activities on the donor and acceptor side of PSII and its correlation with the photoprotection of PSII during photoinhibition. Therefore, we performed systematic and comprehensive investigations of electron transfers on the donor and acceptor sides of photosystem II (PSII) in the Deg1-reduced transgenic lines deg1-2 and deg1-4. Both the maximal quantum efficiency of PSII photochemistry (F_v/F_m) and the actual PSII efficiency (Φ_PSII) decreased significantly in the transgenic plants. Increases in nonphotochemical quenching (NPQ) and the dissipated energy flux per reaction center (DI₀/RC) were also shown in the transgenic plants. Along with the decreased D1, CP47, and CP43 content, these results suggested photoinhibition under growth light conditions in transgenic plants. Decreased Deg1 caused inhibition of electron transfer on the PSII reducing side, leading to a decline in the number of Q_B-reducing centers and accumulation of Q_B-nonreducing centers. The Tm of the Q band shifted from 5.7 °C in the wild-type plant to 10.4 °C and 14.2 °C in the deg1-2 and deg1-4 plants, respectively, indicating an increase in the stability of S₂Q_A^¯ in transgenic plants. PSIIα in the transgenic plants largely reduced, while PSIIβ and PSIIγ increased with the decline in the Deg1 levels in transgenic plants suggesting PSIIα centers gradually converted into PSIIβ and PSIIγ centers in the transgenic plants. Besides, the connectivity of PSIIα and PSIIβ was downregulated in transgenic plants. Our results reveal that downregulation of Deg1 protein levels induced photoinhibition in transgenic plants, leading to loss of PSII activities on both the donor and acceptor sides in transgenic plants. These results give a new insight into the regulation role of Deg1 in PSII electron transport.

Keywords: Chlorophyll Fluorescence; Deg1; Electron transfer; PSII heterogeneity; Photosystem II; Thermoluminescence.

MeSH terms

Arabidopsis* / genetics
Arabidopsis* / metabolism
Chlorophyll
Electron Transport
Electrons
Light
Photosystem II Protein Complex* / genetics
Photosystem II Protein Complex* / metabolism

Substances

Photosystem II Protein Complex
Chlorophyll

Abstract

MeSH terms

Substances

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