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Plant Cell Environ. 2018 Aug;41(8):1727-1738. doi: 10.1111/pce.13332. Epub 2018 Jun 8.

Singlet oxygen-triggered chloroplast-to-nucleus retrograde signalling pathways: An emerging perspective.

Author information

1
Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
2
Department of Molecular Biology and Plant Biology, University of Geneva, 1205, Geneva, Switzerland.

Abstract

Singlet oxygen (1 O2 ) is a prime cause of photo-damage of the photosynthetic apparatus. The chlorophyll molecules in the photosystem II reaction center and in the light-harvesting antenna complex are major sources of 1 O2 generation. It has been thought that the generation of 1 O2 mainly takes place in the appressed regions of the thylakoid membranes, namely, the grana core, where most of the active photosystem II complexes are localized. Apart from being a toxic molecule, new evidence suggests that 1 O2 significantly contributes to chloroplast-to-nucleus retrograde signalling that primes acclimation and cell death responses. Interestingly, recent studies reveal that chloroplasts operate two distinct 1 O2 -triggered retrograde signalling pathways in which β-carotene and a nuclear-encoded chloroplast protein EXECUTER1 play essential roles as signalling mediators. The coexistence of these mediators raises several questions: their crosstalk, source(s) of 1 O2 , downstream signalling components, and the perception and reaction mechanism of these mediators towards 1 O2 . In this review, we mainly discuss the molecular genetic basis of the mode of action of these two putative 1 O2 sensors and their corresponding retrograde signalling pathways. In addition, we also propose the possible existence of an alternative source of 1 O2 , which is spatially and functionally separated from the grana core.

KEYWORDS:

EXECUTER1; acclimation; photoinhibition; programmed cell death; retrograde signalling; singlet oxygen; β-carotene

PMID:
29749057
DOI:
10.1111/pce.13332

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