bims-plasge 2020-05-10 papers

Plants (Basel). 2020 May 01. pii: E573. [Epub ahead of print]9(5):

The Consequences of a Disruption in Cyto-Nuclear Coadaptation on the Molecular Response to a Nitrate Starvation in Arabidopsis.

Fabien Chardon, Gwendal Cueff, Etienne Delannoy, Fabien Aubé, Aurélia Lornac, Magali Bedu, Françoise Gilard, Stéphanie Pateyron, Hélène Rogniaux, Audrey Gargaros, Hakim Mireau, Loïc Rajjou, Marie-Laure Martin-Magniette, Françoise Budar.

Mitochondria and chloroplasts are important actors in the plant nutritional efficiency. So, it could be expected that a disruption of the coadaptation between nuclear and organellar genomes impact plant response to nutrient stresses. We addressed this issue using two Arabidopsis accessions, namely Ct1 and Jea, and their reciprocal cytolines possessing the nuclear genome from one parent and the organellar genomes of the other one. We measured gene expression, and quantified proteins and metabolites under N starvation and non-limiting conditions. We observed a typical response to N starvation at the phenotype and molecular levels. The phenotypical response to N starvation was similar in the cytolines compared to the parents. However, we observed an effect of the disruption of genomic coadaptation at the molecular levels, distinct from the previously described responses to organellar stresses. Strikingly, genes differentially expressed in cytolines compared to parents were mainly repressed in the cytolines. These genes encoded more mitochondrial and nuclear proteins than randomly expected, while N starvation responsive ones were enriched in genes for chloroplast and nuclear proteins. In cytolines, the non-coadapted cytonuclear genomic combination tends to modulate the response to N starvation observed in the parental lines on various biological processes.

Keywords: Arabidopsis thaliana; cytonuclear co adaptation; metabolome; natural variation; nutrient stress; proteome; transcriptome

DOI: https://doi.org/10.3390/plants9050573

Philos Trans R Soc Lond B Biol Sci. 2020 Jun 22. 375(1801): 20190396

Retrograde signals from endosymbiotic organelles: a common control principle in eukaryotic cells.

Thomas Pfannschmidt, Matthew J Terry, Olivier Van Aken, Pedro M Quiros.

Endosymbiotic organelles of eukaryotic cells, the plastids, including chloroplasts and mitochondria, are highly integrated into cellular signalling networks. In both heterotrophic and autotrophic organisms, plastids and/or mitochondria require extensive organelle-to-nucleus communication in order to establish a coordinated expression of their own genomes with the nuclear genome, which encodes the majority of the components of these organelles. This goal is achieved by the use of a variety of signals that inform the cell nucleus about the number and developmental status of the organelles and their reaction to changing external environments. Such signals have been identified in both photosynthetic and non-photosynthetic eukaryotes (known as retrograde signalling and retrograde response, respectively) and, therefore, appear to be universal mechanisms acting in eukaryotes of all kingdoms. In particular, chloroplasts and mitochondria both harbour crucial redox reactions that are the basis of eukaryotic life and are, therefore, especially susceptible to stress from the environment, which they signal to the rest of the cell. These signals are crucial for cell survival, lifespan and environmental adjustment, and regulate quality control and targeted degradation of dysfunctional organelles, metabolic adjustments, and developmental signalling, as well as induction of apoptosis. The functional similarities between retrograde signalling pathways in autotrophic and non-autotrophic organisms are striking, suggesting the existence of common principles in signalling mechanisms or similarities in their evolution. Here, we provide a survey for the newcomers to this field of research and discuss the importance of retrograde signalling in the context of eukaryotic evolution. Furthermore, we discuss commonalities and differences in retrograde signalling mechanisms and propose retrograde signalling as a general signalling mechanism in eukaryotic cells that will be also of interest for the specialist. This article is part of the theme issue 'Retrograde signalling from endosymbiotic organelles'.

Keywords: chloroplasts; intracellular communication; metabolites; mitochondria; plastids; signalling

DOI: https://doi.org/10.1098/rstb.2019.0396

Philos Trans R Soc Lond B Biol Sci. 2020 Jun 22. 375(1801): 20190397

Genome communication in plants mediated by organelle-n-ucleus-located proteins.

Karin Krupinska, Nicolás E Blanco, Svenja Oetke, Michela Zottini.

An increasing number of eukaryotic proteins have been shown to have a dual localization in the DNA-containing organelles, mitochondria and plastids, and/or the nucleus. Regulation of dual targeting and relocation of proteins from organelles to the nucleus offer the most direct means for communication between organelles as well as organelles and nucleus. Most of the mitochondrial proteins of animals have functions in DNA repair and gene expression by modelling of nucleoid architecture and/or chromatin. In plants, such proteins can affect replication and early development. Most plastid proteins with a confirmed or predicted second location in the nucleus are associated with the prokaryotic core RNA polymerase and are required for chloroplast development and light responses. Few plastid-nucleus-located proteins are involved in pathogen defence and cell cycle control. For three proteins, it has been clearly shown that they are first targeted to the organelle and then relocated to the nucleus, i.e. the nucleoid-associated proteins HEMERA and Whirly1 and the stroma-located defence protein NRIP1. Relocation to the nucleus can be experimentally demonstrated by plastid transformation leading to the synthesis of proteins with a tag that enables their detection in the nucleus or by fusions with fluoroproteins in different experimental set-ups. This article is part of the theme issue 'Retrograde signalling from endosymbiotic organelles'.

Keywords: dual localization; genome communication; mitochondria; nucleus; organelles; plastids

DOI: https://doi.org/10.1098/rstb.2019.0397