Heat stress in plants: sensing, signalling and ferroptosis.

In the current context of global warming, high temperature events are becoming more frequent and intense in many places around the world. In this context, understanding how plants sense and respond to heat is essential to develop new tools to prevent plant damage and address global food security, as high temperature events are threatening agricultural sustainability. This review summarizes and integrates our current understanding underlying the cellular, physiological, biochemical and molecular regulatory pathways triggered in plants under moderately high and extremely high temperature conditions.

Cell death in bryophytes: emerging models to study core regulatory modules and conserved pathways.

This review summarizes recent progress in our current understanding of the mechanisms underlying the cell death pathways in bryophytes, focusing on conserved pathways and particularities in comparison to angiosperms. Regulated cell death (RCD) plays key roles during essential processes along the plant life cycle. It is part of specific developmental programmes and maintains homeostasis of the organism in response to unfavourable environments.

Measuring and Perturbing Ferroptosis in Plants.

Ferroptosis is an oxidative iron-dependent cell death that was recently described in vertebrates, invertebrates, fungi, plants, and bacteria. In plants, ferroptosis has been reported in response to heat shock in roots of 6-day-old Arabidopsis thaliana seedlings. Generally, all biochemical and morphological ferroptosis hallmarks are conserved between animals and plants.

Ferroptosis in plants: regulation of lipid peroxidation and redox status.

Regulated cell death (RCD) is an essential process that plays key roles along the plant life cycle. Unlike accidental cell death, which is an uncontrolled biological process, RCD involves integrated signaling cascades and precise molecular-mediated mechanisms that are triggered in response to specific exogenous or endogenous stimuli. Ferroptosis is a cell death pathway characterized by the iron-dependent accumulation of lipid reactive oxygen species.

A mitochondrial ADXR-ADX-P450 electron transport chain is essential for maternal gametophytic control of embryogenesis in .

Mitochondrial adrenodoxins (ADXs) are small iron-sulfur proteins with electron transfer properties. In animals, ADXs transfer electrons between an adrenodoxin reductase (ADXR) and mitochondrial P450s, which is crucial for steroidogenesis. Here we show that a plant mitochondrial steroidogenic pathway, dependent on an ADXR-ADX-P450 shuttle, is essential for female gametogenesis and early embryogenesis through a maternal effect.

Gamma carbonic anhydrases are subunits of the mitochondrial complex I of diatoms.

Diatoms are unicellular organisms containing red algal-derived plastids that probably originated as result of serial endosymbioses between an ancestral heterotrophic organism and a red alga or cryptophyta algae from which has only the chloroplast left. Diatom mitochondria are thus believed to derive from the exosymbiont. Unlike animals and fungi, diatoms seem to contain ancestral respiratory chains.

A Complex Journey: Cell Wall Remodeling, Interactions, and Integrity During Pollen Tube Growth.

In flowering plants, pollen tubes undergo a journey that starts in the stigma and ends in the ovule with the delivery of the sperm cells to achieve double fertilization. The pollen cell wall plays an essential role to accomplish all the steps required for the successful delivery of the male gametes. This extended path involves female tissue recognition, rapid hydration and germination, polar growth, and a tight regulation of cell wall synthesis and modification, as its properties change not only along the pollen tube but also in response to guidance cues inside the pistil.

Heat stress in Marchantia polymorpha: Sensing and mechanisms underlying a dynamic response.

Sensing and response to high temperatures are crucial to prevent heat-related damage and to preserve cellular and metabolic functions. The response to heat stress is a complex and coordinated process that involves several subcellular compartments and multi-level regulatory networks that are synchronized to avoid cell damage while maintaining cellular homeostasis. In this review, we provide an insight into the most recent advances in elucidating the molecular mechanisms involved in heat stress sensing and response in Marchantia polymorpha.

Roles of cytochromes P450 in plant reproductive development.

The cytochrome P450 superfamily is a large enzymatic protein family that is widely distributed along diverse kingdoms. In plants, cytochrome P450 monooxygenases (CYPs) participate in a vast array of pathways leading to the synthesis and modification of multiple metabolites with variable and important functions during different stages of plant development. This includes the biosynthesis and degradation of a great assortment of compounds implicated in a variety of physiological responses, such as signaling and defense, organ patterning and the biosynthesis of structural polymers, among others.

Ferroptosis in plants: triggers, proposed mechanisms, and the role of iron in modulating cell death.

Regulated cell death plays key roles during essential processes throughout the plant life cycle. It takes part in specific developmental programs and maintains homeostasis of the organism in response to unfavorable environments. Ferroptosis is a recently discovered iron-dependent cell death pathway characterized by the accumulation of lipid reactive oxygen species.

Mitochondrial Pentatricopeptide Repeat Protein, EMB2794, Plays a Pivotal Role in NADH Dehydrogenase Subunit nad2 mRNA Maturation in Arabidopsis thaliana.

The Arabidopsis genome encodes >450 proteins containing the pentatricopeptide repeat (PPR) motif. The PPR proteins are classified into two groups, termed as P and P Long-Short (PLS) classes. Typically, the PLS subclass proteins are mainly involved in the RNA editing of mitochondrial and chloroplast transcripts, whereas most of the analyzed P subclass proteins have been mainly implicated in RNA metabolism, such as 5' or 3' transcript stabilization and processing, splicing and translation.

Different Types Domains are Present in Complex I from Immature Seeds and of CA Adult Plants in Arabidopsis thaliana.

Mitochondrial Nicotinamide adenine dinucleotide (NADH) dehydrogenase complex is the first complex of the mitochondrial electron transfer chain. In plants and in a variety of eukaryotes except Opisthokonta, complex I (CI) contains an extra spherical domain called carbonic anhydrase (CA) domain. This domain is thought to be composed of trimers of gamma type CA and CA-like subunits.

Heat stress induces ferroptosis-like cell death in plants.

In plants, regulated cell death (RCD) plays critical roles during development and is essential for plant-specific responses to abiotic and biotic stresses. Ferroptosis is an iron-dependent, oxidative, nonapoptotic form of cell death recently described in animal cells. In animal cells, this process can be triggered by depletion of glutathione (GSH) and accumulation of lipid reactive oxygen species (ROS).

The carbonic anhydrase domain of plant mitochondrial complex I.

The mitochondrial NADH dehydrogenase complex (complex I) consists of several functional domains which independently arose during evolution. In higher plants, it contains an additional domain which includes proteins resembling gamma-type carbonic anhydrases. The Arabidopsis genome codes for five complex I-integrated gamma-type carbonic anhydrases (γCA1, γCA2, γCA3, γCAL1, γCAL2), but only three copies of this group of proteins form an individual extra domain.

The CA domain of the respiratory complex I is required for normal embryogenesis in Arabidopsis thaliana.

The NADH-ubiquinone oxidoreductase [complex I (CI), EC 1.6.5.

Functional characterization of mutants affected in the carbonic anhydrase domain of the respiratory complex I in Arabidopsis thaliana.

The NADH-ubiquinone oxidoreductase complex (complex I) (EC 1.6.5.

Role of mitochondria during female gametophyte development and fertilization in A. thaliana.

Plants alternate between two generations during their life cycle: the diploid sporophyte and the haploid male and female gametophytes, in which gametes are generated. In higher plants, the female gametophyte or embryo sac is a highly polarized seven-celled structure that develops within the sporophytic tissues of the ovule. It has been proposed that mitochondria are crucial in many cell signaling pathways controlling mitosis, cell specification, cell death and fertilization within the embryo sac.

New insights into the functional roles of reactive oxygen species during embryo sac development and fertilization in Arabidopsis thaliana.

Previously considered as toxic by-products of aerobic metabolism, reactive oxygen species (ROS) are emerging as essential signaling molecules in eukaryotes. Recent evidence showed that maintenance of ROS homeostasis during female gametophyte development is crucial for embryo sac patterning and fertilization. Although ROS are exclusively detected in the central cell of mature embryo sacs, the study of mutants deficient in ROS homeostasis suggests that controlled oxidative bursts might take place earlier during gametophyte development.

oiwa, a female gametophytic mutant impaired in a mitochondrial manganese-superoxide dismutase, reveals crucial roles for reactive oxygen species during embryo sac development and fertilization in Arabidopsis.

Reactive oxygen species (ROS) can function as signaling molecules, regulating key aspects of plant development, or as toxic compounds leading to oxidative damage. In this article, we show that the regulation of ROS production during megagametogenesis is largely dependent on MSD1, a mitochondrial Mn-superoxide dismutase. Wild-type mature embryo sacs show ROS exclusively in the central cell, which appears to be the main source of ROS before pollination.

A mitochondrial alkaline/neutral invertase isoform (A/N-InvC) functions in developmental energy-demanding processes in Arabidopsis.

Recent findings demonstrate that alkaline/neutral invertases (A/N-Invs), enzymes that catalyze the breakdown of sucrose into glucose and fructose, are essential proteins in plant life. The fact that different isoforms are present in multiple locations makes them candidates for the coordination of metabolic processes. In the present study, we functionally characterized the encoding gene of a novel A/N-Inv (named A/N-InvC) from Arabidopsis, which localizes in mitochondria.

A basal carbon concentrating mechanism in plants?

Many photosynthetic organisms have developed inorganic carbon (Ci) concentrating mechanisms (CCMs) that increase the CO₂ concentration within the vicinity of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). Several CCMs, such as four carbon (C4) and crassulacean acid metabolism (CAM), bicarbonate accumulation systems and capsular structures around RubisCO have been described in great detail. These systems are believed to have evolved several times as mechanisms that acclimate organisms to unfavourable growth conditions.

Nitric oxide, nitrosyl iron complexes, ferritin and frataxin: a well equipped team to preserve plant iron homeostasis.

Iron is a key element in plant nutrition. Iron deficiency as well as iron overload results in serious metabolic disorders that affect photosynthesis, respiration and general plant fitness with direct consequences on crop production. More than 25% of the cultivable land possesses low iron availability due to high pH (calcareous soils).

Effect of mitochondrial dysfunction on carbon metabolism and gene expression in flower tissues of Arabidopsis thaliana.

We characterized the transcriptomic response of transgenic plants carrying a mitochondrial dysfunction induced by the expression of the unedited form of the ATP synthase subunit 9. The u-ATP9 transgene driven by A9 and APETALA3 promoters induce mitochondrial dysfunction revealed by a decrease in both oxygen uptake and adenine nucleotides (ATP, ADP) levels without changes in the ATP/ADP ratio. Furthermore, we measured an increase in ROS accumulation and a decrease in glutathione and ascorbate levels with a concomitant oxidative stress response.

Recombinant plant gamma carbonic anhydrase homotrimers bind inorganic carbon.

Gamma carbonic anhydrases (gammaCA) are widespread in Prokaryotes. In Eukaryotes, homologous genes were found only in plant genomes. In Arabidopsis and maize, the corresponding gene products are subunits of mitochondrial Complex I.