Search Results (90)

Reactive oxygen species (ROS) are among the most effective tools of the innate immune response against pathogenic microbes. The respiratory burst (RB) of polymorphonuclear leukocytes (PMNs) generates an electron current that reduces molecular oxygen to superoxide. Superoxide reacts to form hydrogen peroxide as a precursor to the highly bactericidal hypochlorous acid. Here, we investigated whether alterations in extracellular potassium concentration impact H₂O₂ production. Such changes may occur, for example, during massive cell death due to necrosis or due to trauma injuries when potassium diffuses out of the cells. We recorded H₂O₂ release over a 2 h period of RB under varying potassium concentrations. Except for 100 mM potassium chloride, which increased the time delay before detectable H₂O₂ production, none of the potassium concentrations had a substantial effect on RB. We further examined whether this effect depended on the specific monovalent ion species. When sodium or methanesulfonate was used instead of potassium or chloride, respectively, no changes in H₂O₂ production were observed. Cell volume measurements under different potassium concentrations showed that only 100 mM potassium chloride significantly shrank the cells. We propose that hypertonic stress is crucial for delaying RB in human granulocytes, whereas the RB itself is independent of the tested ionic species. Additionally, the conducted hypertonic stress experiments revealed an unexpected time-dependence during the course of the RB, showing that the first 6 min were almost inert to hyperosmotic stress. Full article

Plant respiratory burst oxidase homolog (Rboh) genes are integral to the production of reactive oxygen species (ROS) and the regulation of stress responses. Here, bioinformatic techniques were employed to identify eight PgRboh genes (PgRbohA–H) in the genome of pomegranate (Punica granatum L.) and conduct a systematic analysis of this family. The findings showed that all PgRbohs proteins possess characteristic NADPH oxidase domains and are predicted to be localized on the cell membrane. Experimental verification confirmed the membrane localization of PgRbohD and PgRbohE proteins. Phylogenetic analysis categorized the PgRbohs proteins into six distinct groups, suggesting potential functional divergence among these groups. Promoter analysis revealed a significant presence of cis-acting elements responsive to low-temperature and methyl jasmonate (MeJA). The expression of PgRboh genes was found to be tissue-specific. Additionally, real-time PCR (RT-qPCR) was used to analyze expression patterns in response to low-temperature stress that involves multiple PgRboh genes in the cold response process. Overall, our results lay an important foundation for subsequent studies on the cold resistance function of pomegranate Rboh genes and provides new ideas for the breeding of new cold-resistant pomegranate varieties. Full article

The application of an environmentally friendly plant growth regulator to regulate plant growth and development represents a promising strategy for sustainable agriculture. Thymol is a kind of plant-derived natural compound. We have found that thymol is a potential biostimulant with the capability to trigger plant defense against abiotic stresses. Little is known about whether and how thymol modulates plant root system architecture. In this study, physiological, histochemical, and molecular approaches were applied to identify the role of thymol in promoting lateral root development in watermelon seedlings. Thymol significantly promoted LRP (lateral root primordia) initiation and lateral root formation. Rboh (respiratory burst oxidase homolog)-dependent reactive oxygen species (ROS) generation was involved in thymol-promoted lateral root development from LRP. Then, the Rboh gene family with nine members (ClRboh1–ClRboh9) was identified from watermelon genome. Thymol significantly induced the expression of a set of ClRbohs in roots. These results suggested that thymol was able to stimulate lateral root formation by triggering Rboh-dependent ROS production. These findings may help understand the biological function of thymol as an elicitor of lateral root in both applied and fundamental study. Full article

The plant respiratory burst oxidase homologs (RBOHs) are crucial enzymes responsible for the production of reactive oxygen species (ROS) in plants, playing a pivotal role in regulating various aspects of plant growth, development, and stress responses. While RBOH family members have been identified across a wide range of plant species, the functions and characteristics of the RBOH gene family in oats remain poorly understood. In this study, 35 members of the RBOH gene family in the oat genome were identified using bioinformatics approaches. Conserved motif and gene structure analyses revealed that most AsRBOH genes contain Motif4 and Motif5. Phylogenetic tree analysis demonstrated that the AsRBOHs can be classified into five distinct subfamilies. Synteny analysis indicated that AsRBOHs share the highest number of syntenic gene pairs with wheat. Additionally, cis-regulatory element analysis identified several elements associated with drought and hypoxia-specific responses in AsRBOHs. Expression analysis using qRT-PCR showed that 28 AsRBOH genes were upregulated under drought stress, while 18 were downregulated under salt stress. Notably, the genes 7DG1382190 and 7AG1225850 were found to be involved in both drought and salt stress responses. In conclusion, these findings provide a valuable foundation for future functional studies of the AsRBOH gene family in oats, offering insights that could contribute to the improvement and innovation of oat varieties and germplasm. Full article

Living organisms are constantly exposed to various DNA damaging agents. While the mechanisms of DNA damage and DNA repair are well understood, the impact of these agents on RNA secondary structure and subsequent function remains elusive. In this study, we explore the effects of DNA damaging reagent methyl methanesulfonate (MMS) on arabidopsis gene expression and RNA secondary structure using the dimethyl sulfate (DMS) mutational profiling with sequencing (DMS-MaPseq) method. Our analyses reveal that changes in transcriptional levels and mRNA structure are key factors in response to DNA damaging agents. MMS treatment leads to the up-regulation of arabidopsis RBOHs (respiratory burst oxidase homologues) and alteration in the RNA secondary structure of GSTF9 and GSTF10, thereby enhancing mRNA translation efficiency. Redox homeostasis manipulated by RBOHs and GSTFs plays a crucial role in MMS-induced primary root growth inhibition. In conclusion, our findings shed light on the effects of DNA damaging agents on RNA structure and potential mRNA translation, which provide a new insight to understand the mechanism of DNA damage. Full article

Flooding causes severe yield losses worldwide, making it urgent to enhance crop tolerance to this stress. Since natural flooding often involves physical flow, we hypothesized that the effects of submergence on plants could change when combined with physical flow. In this study, we analyzed the growth and transcriptome of Arabidopsis thaliana exposed to submergence or flooding with physical flow. Plants exposed to flooding with physical flow had smaller rosette diameters, especially at faster flow rates. Transcriptome analysis revealed that “defense response” transcripts were highly up-regulated in response to flooding with physical flow. In addition, up-regulation of transcripts encoding ROS-producing enzymes, SA synthesis, JA synthesis, and ethylene signaling was more pronounced under flooding with physical flow when compared to submergence. Although H₂O₂ accumulation changed in response to submergence or flooding with physical flow, it did not lead to lipid peroxidation, suggesting a role for ROS as signaling molecules under these conditions. Multiple regression analysis indicated possible links between rosette diameter under flooding with physical flow and the expression of Rbohs and SA synthesis transcripts. These findings suggest that pathogen defense responses, regulated by SA and ROS signaling, play crucial roles in plant responses to flooding with physical flow. Full article

Plant respiratory burst oxidase homologs (Rbohs) are key enzymes that produce reactive oxygen species (ROS), which serve as signaling molecules regulating plant growth and stress responses. In this study, 39 TaRboh genes (TaRboh01–TaRboh39) were identified. These genes were distributed unevenly among the wheat genome’s fourteen chromosomes, with the exception of homoeologous group 2 and 7 and chromosomes 4A, as well as one unidentified linkage group (Un). TaRbohs were classified into ten distinct clades, each sharing similar motif compositions and gene structures. The promoter regions of TaRbohs contained cis-elements related to hormones, growth and development, and stresses. Furthermore, five TaRboh genes (TaRboh26, TaRboh27, TaRboh31, TaRboh32, and TaRboh34) exhibited strong evolutionary conservation. Additionally, a Ka/Ks analysis confirmed that purifying selection was the predominant force driving the evolution of these genes. Expression profiling and qPCR results further indicated differential expression patterns of TaRboh genes between heat and drought stresses. TaRboh11, TaRboh20, TaRboh22, TaRboh24, TaRboh29, and TaRboh34 were significantly upregulated under multiple stress conditions, whereas TaRboh30 was only elevated in response to drought stress. Collectively, our findings provide a systematic analysis of the wheat Rboh gene family and establish a theoretical framework for our future research on the role of Rboh genes in response to heat and drought stress. Full article

Flowering plants require normal pollen germination and growth to be fertilized, but studies on the mechanism regulating pollen tube growth in Fraxinus mandshurica are limited. Here, we used transcriptomic data to study the oxidative phosphorylation pathway during pollen tube growth in Fraxinus mandshurica. Our study identified 8,734 differentially expressed genes during the stages S1 to S3 of pollen tube growth. Significant enrichment of the oxidative phosphorylation pathway, amino acid synthesis, protein processing in the ER, carbon metabolism, pyruvate metabolism, citrate cycle (TCA cycle), and glycolysis/gluconeogenesis were examined using the Kyoto Encyclopedia of Genes and Genomes, and 58 genes linked to ROS synthesis and scavenging during the S1–S3 stages were identified. Also, H₂DCFDA staining confirmed ROS formation in the pollen and the pollen tubes, and treatment with copper (II) chloride (CuCl₂) and diphenyleneiodonium (DPI) was shown to reduce ROS in the pollen tube. Reduction in ROS content caused decreased pollen germination and pollen tube length. Furthermore, FmRbohH (respiratory burst oxidase homolog H) expression was detected in the pollen and pollen tube, and an antisense oligodeoxynucleotide assay demonstrated reduced ROS and pollen tube growth in Fraxinus mandshurica. This study shed more light on the RbohH gene functions during pollen tube growth. Full article

Chinese cabbage (Brassica rapa L. ssp. pekinensis) is an important food crop. However, its growth and development are commonly impacted by black spot disease. To examine the response mechanisms of Chinese cabbage to black spot disease, transcriptome and metabolome sequencing were performed on the leaves of Chinese cabbage genotypes J405 (resistant) and B214 (susceptible), 48 h post-infection (hpi) with Alternaria brassicicola. Expression of essential genes in the jasmonic acid, cytokinin, and auxin signaling pathways of both Chinese cabbage genotypes was inhibited. The expression of the pathogenesis-related protein 1 (PR1) gene mediated by the salicylic acid pathway is inhibited in the Chinese cabbage genotype B214. The basic endochitase B (CHIB) gene in the ethylene pathway of both Chinese cabbage genotypes was upregulated. The accumulation of reactive oxygen species in the disease spots of Chinese cabbage genotype J405 was greater than in genotype B214. The respiratory burst oxidase (RBOH) gene in the reactive oxygen species metabolic pathway was significantly upregulated in genotype J405, while no change was observed in genotype B214. We found that oxidation-reduction-related genes such as type-2 peroxiredoxin genes, NADPH-dependent thioredoxin reductase genes, glutathione peroxidase genes, and glutathione S-transfer genes were differentially expressed across both Chinese cabbage genotypes at 48 hpi. Metabolomics demonstrated that delta-tocopherol and S-hexyl glutathione were all downregulated in genotype J405, while they were upregulated in genotype B214. This approach also identified differential expression of genes in the carotenoid biosynthesis pathway, the glycinebetaine biosynthesis pathway, as well as in the specific sulfur glycoside metabolism pathway. These findings indicate that ethylene signaling is important in the hormone signaling regulatory network-mediated disease resistance and defense in Chinese cabbage. When facing pathogen infection, hormone transduction pathways associated with growth and development in Chinese cabbage are inhibited. The accumulation of reactive oxygen species and the outbreak of various secondary metabolites may endow the Chinese cabbage genotype J405 with increased resistance to black spot disease. Full article

Respiratory burst oxidase homologs (Rbohs) are the primary producers of reactive oxygen species (ROS), which have been demonstrated to play critical roles in plant responses to abiotic stress. Here, we explored the function of OsRbohH in heat and drought stress tolerance by generating overexpression lines (OsRbohH-OE). OsRbohH was highly induced by various abiotic stress and hormone treatments. Compared to wild-type (WT) controls, OsRbohH-OE plants exhibited enhanced tolerance to heat and drought, as determined by survival rate analyses and total chlorophyll content. Histochemical staining revealed that OsRbohH-OE accumulated less ROS. This is consistent with the observed increase in catalase (CAT) and peroxidase (POD) activities, as well as a reduced electrolyte leakage rate and malondialdehyde (MDA) content. Moreover, OsRbohH-OE exhibited enhanced sensitivity to exogenous abscisic acid (ABA), accompanied by altered expression levels of ABA synthesis and catabolic genes. Further analysis indicated that transgenic lines had lower transcripts of ABA signaling-related genes (OsDREB2A, OsLEA3, OsbZIP66, and OsbZIP72) under heat but higher levels under drought than WT. In conclusion, these results suggest that OsRbohH is a positive regulator of heat and drought tolerance in rice, which is probably performed through OsRbohH-mediated ROS homeostasis and ABA signaling. Full article

Normal root growth is essential for the plant uptake of soil nutrients and water. However, exogenous H₂O₂ inhibits the gravitropic growth of pea primary roots. It has been shown that CaCl₂ application can alleviate H₂O₂ inhibition, but the exact alleviation mechanism is not clear. Therefore, the present study was carried out by combining the transcriptome and metabolome with a view to investigate in depth the mechanism of action of exogenous CaCl₂ to alleviate the inhibition of pea primordial root gravitropism by H₂O₂. The results showed that the addition of CaCl₂ (10 mmol·L⁻¹) under H₂O₂ stress (150 mmol·L⁻¹) significantly increased the H₂O₂ and starch content, decreased peroxidase (POD) activity, and reduced the accumulation of sugar metabolites and lignin in pea primary roots. Down-regulated genes regulating peroxidase, respiratory burst oxidase, and lignin synthesis up-regulated PGM1, a key gene for starch synthesis, and activated the calcium and phytohormone signaling pathways. In summary, 10 mmol·L⁻¹ CaCl₂ could alleviate H₂O₂ stress by modulating the oxidative stress response, signal transduction, and starch and lignin accumulation within pea primary roots, thereby promoting root gravitropism. This provides new insights into the mechanism by which CaCl₂ promotes the gravitropism of pea primary roots under H₂O₂ treatment. Full article

Chronic granulomatous disease (CGD) is a group of rare primary inborn errors of immunity characterised by a defect in the phagocyte respiratory burst, which leads to severe and life-threatening infective and inflammatory complications. Despite recent advances in our understanding of the genetic and molecular pathophysiology of X-linked and autosomal recessive CGD, and growth in the availability of functional and genetic testing, there remain significant barriers to early and accurate diagnosis. In the current review, we provide an up-to-date summary of CGD pathophysiology, underpinning current methods of diagnostic testing for CGD and closely related disorders. We present an overview of the benefits of early diagnosis and when to suspect and test for CGD. We discuss current and historical methods for functional testing of NADPH oxidase activity, as well as assays for measuring protein expression of NADPH oxidase subunits. Lastly, we focus on genetic and genomic methods employed to diagnose CGD, including gene-targeted panels, comprehensive genomic testing and ancillary methods. Throughout, we highlight general limitations of testing, and caveats specific to interpretation of results in the context of CGD and related disorders, and provide an outlook for newborn screening and the future. Full article

In plant models such as Arabidopsis thaliana, phosphatidic acid (PA), a key molecule of lipid signaling, was shown not only to be involved in stress responses, but also in plant development and nutrition. In this article, we highlight lipid signaling existing in crop species. Based on open access databases, we update the list of sequences encoding phospholipases D, phosphoinositide-dependent phospholipases C, and diacylglycerol-kinases, enzymes that lead to the production of PA. We show that structural features of these enzymes from model plants are conserved in equivalent proteins from selected crop species. We then present an in-depth discussion of the structural characteristics of these proteins before focusing on PA binding proteins. For the purpose of this article, we consider RESPIRATORY BURST OXIDASE HOMOLOGUEs (RBOHs), the most documented PA target proteins. Finally, we present pioneering experiments that show, by different approaches such as monitoring of gene expression, use of pharmacological agents, ectopic over-expression of genes, and the creation of silenced mutants, that lipid signaling plays major roles in crop species. Finally, we present major open questions that require attention since we have only a perception of the peak of the iceberg when it comes to the exciting field of phospholipid signaling in plants. Full article

Respiratory burst oxidase homologs (RBOHs), also known as NADPH oxidases, contribute significantly to the production of ROS in plants, alongside other major sources such as photosynthesis and electron transport in chloroplasts. It has been shown that plant RBOHs play an active role in plant adversity response and electron transport. However, the phylogenetic analysis and characterization of the SlRBOH gene family in tomatoes have not been systematically studied. This study identified 11 SlRBOH genes in the tomato genome using a genome-wide search approach. The physicochemical properties, chromosomal localization, subcellular localization, secondary structure, conserved motifs, gene structure, phylogenetics, collinear relationships, cis-acting elements, evolutionary selection pressures, tissue expressions, and expression patterns under exogenous phytohormones (ABA and MeJA) and different abiotic stresses were also analyzed. We found that the SlRBOHs are distributed across seven chromosomes, collinearity reflecting their evolutionary relationships with corresponding genes in Arabidopsis thaliana and rice. Additionally, all the SlRBOH members have five conserved domains and 10 conserved motifs and have similar gene structures. In addition, the results of an evolutionary selection pressure analysis showed that SlRBOH family members evolved mainly by purifying selection, making them more structurally stable. Cis-acting element analyses showed that SlRBOHs were responsive to light, hormone, and abiotic stresses. Tissue expression analysis showed that SlRBOH family members were expressed in all tissues of tomato to varying degrees, and most of the SlRBOHs with the strongest expression were found in the roots. In addition, the expressions of tomato SlRBOH genes were changed by ABA, MeJA, dark period extension, NaCl, PEG, UV, cold, heat, and H₂O₂ treatments. Specifically, SlRBOH4 was highly expressed under NaCl, PEG, heat, and UV treatments, while SlRBOH2 was highly expressed under cold stress. These results provide a basis for further studies on the function of SlRBOHs in tomato. Full article

Pithiness is one of the physiological diseases of radishes, which is accompanied by the accumulation of reactive oxygen species (ROS) during the sponging of parenchyma tissue in the fleshy roots. A respiratory burst oxidase homolog (Rboh, also known as NADPH oxidase) is a key enzyme that catalyzes the production of ROS in plants. To understand the role of Rboh genes in radish pithiness, herein, 10 RsRboh gene families were identified in the genome of Raphanus sativus using Blastp and Hmmer searching methods and were subjected to basic functional analyses such as phylogenetic tree construction, chromosomal localization, conserved structural domain analysis, and promoter element prediction. The expression profiles of RsRbohs in five stages (Pithiness grade = 0, 1, 2, 3, 4, respectively) of radish pithiness were analyzed. The results showed that 10 RsRbohs expressed different levels during the development of radish pithiness. Except for RsRbohB and RsRbohE, the expression of other members increased and reached the peak at the P2 (Pithiness grade = 2) stage, among which RsRbohD1 showed the highest transcripts. Then, the expression of 40 genes related to RsRbohD1 and pithiness were analyzed. These results can provide a theoretical basis for improving pithiness tolerance in radishes. Full article