Márcia Margis-Pinheiro

Universidade Federal do Rio Grande do Sul | UFRGS · Departamento de Genética

We review the newly classified ascorbate peroxidase–related (APX-R) proteins, which do not use ascorbate as electron donor to scavenge H2O2. We summarize recent discoveries on the function and the characterization of the APX-R protein of the green unicellular alga Chlamydomonas reinhardtii and the land plant Arabidopsis thaliana. Additionally, we c...

Understanding the evolution and the effect of plasticity in plant responses to environmental changes is crucial to combat global climate change. It is particularly interesting in species that survive in distinct environments, such as Eugenia uniflora, which thrives in contrasting ecosystems within the Atlantic Forest (AF). In this study, we combine...

Anther development is a complex process essential for plant reproduction and crop yields. In recent years, significant progress has been made in the identification and characterization of the bHLH transcription factor family involved in anther regulation in rice and Arabidopsis, two extensively studied model plants. Research on bHLH transcription f...

We have previously shown that rice plants silenced for peroxisomal ascorbate peroxidase (OsAPX4-RNAi) display higher resilience to photosynthesis under oxidative stress and photorespiratory conditions. However, the redox mechanisms underlying that intriguing response remain unknown. Here, we tested the hypothesis that favorable effects triggered by...

Chloroplast ascorbate peroxidases exert an important role in the maintenance of hydrogen peroxide levels in chloroplasts by using ascorbate as the specific electron donor. In this work, we performed a functional study of the stromal APX in rice (OsAPX7) and demonstrated that silencing of OsAPX7 did not impact plant growth, redox state, or photosynt...

Abstract The diversity of diacylglycerol acyltransferases (DGATs) indicates alternative roles for these enzymes in plant metabolism besides triacylglycerol (TAG) biosynthesis. In this work, we functionally characterized castor bean (Ricinus communis L.) DGATs assessing their subcellular localization, expression in seeds, capacity to restore triacyl...

Abstract Ascorbate peroxidases (APXs) are heme peroxidases involved in the control of hydrogen peroxide levels and signal transduction pathways related to development and stress responses. Here, a total of 238 APX, 30 APX-related (APX-R), and 34 APX-like (APX-L) genes were identified from 24 species from the Poaceae family. Phylogenetic analysis of...

Ascorbate peroxidase (APX), Monodehydroascorbate Reductase (MDAR), Dehydroascorbate Reductase (DHAR) and Glutathione Reductase (GR) enzymes participate in the ascorbate-glutathione cycle, which exerts a central role in the antioxidant metabolism in plants. Despite the importance of this antioxidant system in different signal transduction networks r...

Ascorbate peroxidases (APXs) are heme peroxidases that remove hydrogen peroxide in different subcellular compartments with concomitant ascorbate cycling. Here, we analyzed and discussed phylogenetic and molecular features of the APX family. Ancient APX originated as a soluble stromal enzyme and, early during plant evolution, acquired both chloropla...

Although mitochondria have a central role in energy transduction and reactive oxygen species (ROS) production, the regulatory mechanisms and their involvement in plant stress signaling are not fully established. The phytohormone salicylic acid (SA) is an important regulator of mitochondria-mediated ROS production and defense signaling. The role of...

There is large diversity among glutathione peroxidase (GPx) enzymes regarding their function, structure, presence of the highly reactive selenocysteine (SeCys) residue, substrate usage, and reducing agent preference. Moreover, most vertebrate GPxs are very distinct from non-animal GPxs, and it is still unclear if they came from a common GPx ancesto...

Background Salt stress negatively affects rice growth and yield in many parts of the world. Cultivated rice (Oryza sativa L.) is very sensitive to salt stress. Breeding attempts to develop salinity-adapted rice varieties have been hampered by the quantitative nature of adaptation and limited genetic variability in cultivated rice. Aims We aimed to...

Ascorbate peroxidases (APX) are class I members of the Peroxidase-Catalase superfamily, a large group of evolutionarily related but rather divergent enzymes. Through mining in public databases, unusual subsets of APX homologs were identified, disclosing the existence of two yet uncharacterized families of peroxidases named ascorbate peroxidase-rela...

Iron (Fe) toxicity is one of the most common mineral disorders affecting rice (Oryza sativa) production in flooded low-land fields. Oryza meridionalis is indigenous to northern Australia and grows in regions with Fe-rich soils, making it a candidate for use in adaptive breeding. With the aim of understanding tolerance mechanisms in rice, we screene...

Peroxidases are enzymes that catalyze the reduction of hydrogen peroxide, thus minimizing cell injury and modulating signaling pathways as response to this reactive oxygen species. Using a phylogenetic approach, we previously identified a new peroxidase family composed of a small subset of ascorbate peroxidase (APx) homologs with distinguished feat...

Anther development is a complex process regulated by a myriad of transcription factors belonging to distinct protein families. In this study, we focus on the functional characterization of OsbHLH35, a basic Helix-Loop-Helix (bHLH) TF that regulates anther development in rice. Plants overexpressing OsbHLH35 presented small and curved anthers, leadin...

Different environmental conditions can lead plants to a condition termed oxidative stress, which is characterized by a disruption in the equilibrium between the production of reactive oxygen species (ROS) and antioxidant defenses. Glutathione peroxidase (GPX), an enzyme that acts as a peroxide scavenger in different organisms, has been identified a...

Iron (Fe) toxicity is one of the most common mineral disorders affecting rice (Oryza sativa) production in flooded lowland fields. Oryza meridionalis is endemic from Northern Australia and grows in regions with Fe rich soils, making it a candidate for use in adaptive breeding. Aiming to understand tolerance mechanisms in rice, we screened a populat...

- Growth Regulating Factors (GRFs) comprise a transcription factor family with important functions in plant growth and development. They are characterized by the presence of QLQ and WRC domains, responsible for interaction with proteins and DNA, respectively. The QLQ domain is named due to the similarity to a protein interaction domain found in the...

Programmed cell death (PCD) is a genetically controlled process that leads to cell suicide in both eukaryotic and prokaryotic organisms. In plants PCD occurs during development, defence response and when exposed to adverse conditions. PCD acts controlling the number of cells by eliminating damaged, old, or unnecessary cells to maintain cellular hom...

Phosphorus (P) is a major essential macronutrient for plants, and its availability in the soil is scarce and not renewable. Molecular responses to low concentrations of inorganic phosphate (Pi) are better understood in Arabidopsis, whereas several information gaps still exist in crops. In addition, rice has invaluable socio-economic importance and...

Key message MdoDHN11 acts in the nucellus layer to protect the embryo and the endosperm from limited water availability during apple seed development. Abstract Dehydrins (DHNs) are protective proteins related to several plant developmental responses that involve dehydration such as seed desiccation and abiotic stresses. In apple (Malus × domestica...

Environmental factors can trigger the accumulation of reactive oxygen species (ROS) in plant cells. These molecules at a basal level are associated with essential cellular functions such as signaling for both developmental and defense responses in plants. On the other hand, ROS at high concentrations are significantly detrimental, leading to oxidat...

Alkaloids are important compounds found in Nicotiana plants, essential in plant defense against herbivores. The main alkaloid of Nicotiana tabacum, nicotine, is produced in roots and translocated to the leaves. Nicotine is formed by a pyrrolidine and a pyridine ring in a process involving several enzymes. The pyridine ring of nicotine is derived fr...

Triacylglycerols (TAG) are the major form of energy storage in plants. TAG are primarily stored in seeds and fruits, but vegetative tissues also possess a high capacity for their synthesis and storage. These storage lipids are essential to plant development, being used in seedling growth during germination, pollen development, and sexual reproducti...

PLAC8 is a cysteine-rich protein described as a central mediator of tumor evolution in mammals; as such, it represents a promising candidate for diagnostic and therapeutic targeting. The human PLAC8 gene is also involved in contact hypersensitivity response and presents a role in psoriatic skin. In plants, PLAC8 motif-containing proteins are involv...

Retrograde signalling pathways, triggered by changes in cellular redox homeostasis, remain poorly understood. Transformed rice plants that are deficient in peroxisomal APX4 (RNAiOsAPX4) exhibit more effective protection of photosynthesis than controls when catalase (CAT) is inhibited, but the mechanisms involved have not been characterised. An in-d...

Rice is one of the world's most important crops and an excellent model system for understanding the interaction between genes and environmental changes. However, its productivity is often challenged by abiotic stresses, which results in the accumulation of reactive oxygen species. Glutathione peroxidases are part of the mechanism by which plants fa...

Chloroplast APX isoforms display controversial roles as H2O2 scavengers and signaling players in response to abiotic stress and conclusive results are lacking. We tested the hypothesis that thylakoidal APX displays an important role for drought tolerance, especially by regulating abundance of essential protein species. For this, OsApx8 RNAi-silence...

sn-Glycerol-3-phosphate 1-O-acyltransferase (GPAT) is an important enzyme that catalyzes the transfer of an acyl group from acyl-CoA or acyl-ACP to the sn-1 or sn-2 position of sn-glycerol-3-phosphate (G3P) to generate lysophosphatidic acids (LPAs). The functional studies of GPAT in plants demonstrated its importance in controlling storage and memb...

In rice (Oryza sativa L.) there are two chloroplast ascorbate peroxidases isoforms, OsAPX7 (stromal) and OsAPX8 (thylakoidal). Previous works demonstrated that double silencing of OsAPX7 and OsAPX8 led to differences in photosynthetic parameters in stress conditions. Nevertheless, both APX encoding genes present contrasting expression patterns in r...

Toxicity caused by high concentrations of ascorbic acid (AA) has been widely reported in animal cells but is scarcely described in plants. In this study, rice plants deficient (knockdown) in two chloroplast ascorbate peroxidases (APX7/8) and non-transformed (NT) were exposed to wide exogenous AA concentrations in the presence of low light and high...

Seedlessness in grapes is a desirable trait, especially for in natura consumption. Previously, we showed that VviAGL11 is the main responsible gene for seed morphogenesis in grapevine. Here we tested the function of this gene in grapevine with the use of plant plasmids. VviAGL11 was cloned into silencing and overexpression versions of p28iIR plasmi...

Drought is a major environmental threat to agriculture sustainability. We have characterised the role of OsICE1, a basic helix-loop-helix (bHLH) transcription factor from rice (Oryza sativa L.), in response to drought. OsICE1 gene is constitutively expressed in roots and shoots of rice seedlings grown under control conditions, as well as in respons...

Galactinol synthase (GolS) is a key enzyme in the biosynthetic pathway of raffinose family oligosaccharides (RFOs), which play roles in carbon storage, signal transduction, and osmoprotection. The present work assessed the evolutionary history of GolS genes across the Rosaceae using several bioinformatic tools. Apple (Malus × domestica) GolS genes...

Lipopolysaccharide-induced tumor necrosis factor-α (LITAF) is a membrane protein that is highly dependent on correct location to exert transcription factor activity and protein quality control. In humans, LITAF, PIG7 (p53-inducible gene 7), and SIMPLE (small integral membrane protein of the lysosome/late endosome) refer to the same gene, which acts...

- Information on the GPAT sequences retrieved in this study.

- Microarray data analysis of GPATs in developmental stages of Arabidopsis thaliana.

- Information about similarity with the respective Arabidopsis gene

- Microarray data analysis GPATs in anatomical parts of Glycine max.

- Microarray data analysis of GPATs in developmental stages of Zea mays.

- Predictions of transmembrane domains of plant GPAT proteins.

- Properties of GPAT protein sequences of representative species.

- Microarray data analysis of GPATs in anatomical parts of Arabidopsis thaliana.

- Microarray data analysis from of GPATs in developmental stages of Glycine max.

- Microarray data analysis of GPATs in anatomical parts of Oryza sativa.

- Microarray data analysis of GPATs in developmental stages of Oryza sativa.

- Microarray data analysis of GPATs in anatomical parts of Zea mays.

Seedlessness is one of the most appreciated traits for table grapes. Previous data confirmed that the MADS-box VvAGL11 grapevine gene is essential for seed morphogenesis by complementation analysis in Arabidopsis agl11 mutants. Plant plasmids turn out to be a useful approach for functional gene studies without the traditional laborious somatic embr...

H2O2, which is continually produced by aerobic metabolism, is a cytotoxic molecule when in high levels. However, low levels can act as a signaling molecule able to regulate the expression of stress responses, senescence, programmed cell death, plant growth, and development. Ascorbate peroxidase (APX) enzyme plays an essential role in the control of...

Heavy metals are natural non-biodegradable constituents of the Earth's crust that accumulate and persist indefinitely in the ecosystem as a result of human activities. Since the industrial revolution, the concentration of cadmium, arsenic, lead, mercury and zinc, amongst others, have increasingly contaminated soil and water resources, leading to si...

Despite the wide appreciation of seedless grapes, little is known about the molecular mechanisms that drive the stenospermocarpic seedless-type phenotype in grapevine. In order to address the molecular mechanisms that control seedlessness in grapevine, our study aimed to characterize VviAGL11, a class D MADS-box transcription factor gene that has b...

Fumarate and succinate are known to be present in prebiotic systems essential for the origin of life. The fumarate and succinate interconversion reactions have been conserved throughout evolution and are found in all living organisms. The fumarate and succinate interconversion is catalyzed by the enzymes succinate dehydrogenase (SDH) and fumarate r...

Since the first diacylglycerol acyltransferase (DGAT) gene was characterized in plants, a number of studies have focused on understanding the role of DGAT activity in plant triacylglycerol (TAG) biosynthesis. DGAT enzyme is essential in controlling TAGs synthesis and is encoded by different genes. DGAT1 and DGAT2 are the two major types of DGATs an...

Drought limits wheat production in the Brazilian Cerrado biome. In order to search for candidate genes associated to the response to water deficit, we analyzed the gene expression profiles, under severe drought stress, in roots and leaves of the cultivar MGS1 Aliança, a well-adapted cultivar to the Cerrado. A set of 4,422 candidate genes was found...

Phytocystatins are well-known inhibitors of C1A cysteine proteinases. However, previous research has revealed legumain (C13) protease inhibition via a carboxy-extended phytocystatin. Among the 12 phytocystatins genes in rice, OcXII is the only gene possessing this carboxy-terminal extension. The specific legumain inhibition activity was confirmed,...

Salinity and osmotic stress trigger distinct signals in roots, which might induce differences in antioxidant responses. To clarify these relationships, transgenic rice plants silenced in both cytosolic ascorbate peroxidases (apx1/2) and non-transformed (NT) were exposed to iso-osmotic concentrations of NaCl and mannitol. Under both stress condition...

The E2 promoter binding factor (E2F) proteins are present in almost all eukaryotic organisms and are essential to control several processes, such as the cell cycle progression, cell division, DNA replication, and apoptosis. The E2F family comprises two different types of proteins: the typical E2Fs and atypical E2Fs, which differ structurally and ha...

The physiological role of plant mitochondrial glutathione peroxidases is scarcely known. This study attempted to elucidate the role of a rice mitochondrial isoform (GPX1) in photosynthesis under normal growth and salinity conditions. GPX1 knockdown rice lines (GPX1s) were tested in absence and presence of 100 mM NaCl for six days. Growth reduction...

- Biological pathways activated in wheat under drought (Blast2GO and KEGG analysis)

Species, gene name, accession numbers and protein length of DGAT sequences retrieved in this study.

Soybean seed development stages (R-stages) used in this study.

Multiple sequence alignment of predicted amino acid sequences of WS/DGAT proteins.

- Correlation of transcript levels between RNA-seq and RT-qPCR data.

- Transcription factor distribution by family.

- Set of 4,422 candidate genes identified in root and leaf tissues of the wheat cultivar MGS1 Aliança under drought.

List of selected diacylglycerol acyltranferase (DGAT) genes used in the GENEVESTIGATOR expression analysis.