ROS Signaling Research Articles

The wheat receptor-like cytoplasmic kinase TaRLCK1B is required for host immune response to the necrotrophic pathogen Rhizoctonia cerealis

Receptor-like cytoplasmic kinases (RLCKs) represent a large family of proteins in plants. In Arabidopsis and rice, several RLCKs in subfamily VII (RLCKs-VII) have been implicated in pathogen-associated molecular pattern-triggered immunity and basal resistance against bacterial and fungal pathogens. However, little is known about roles of RLCKs-VII of the important crop common wheat (Triticum aestivum) in immune responses. Here, we isolated a RLCK-VII-encoding gene from wheat, designated as TaRLCK1B, and investigated its role in host immune response to infection of a necrotrophic fungus Rhizoctonia cerealis that is a major pathogen of sharp eyespot, a destructive disease of wheat. RNA-sequencing and RT-qPCR analyses showed that transcriptional level of TaRLCK1B was significantly higher in sharp eyespot-resistant wheat cultivars than in susceptible wheat cultivars. The gene transcription was rapidly and markedly elevated in the resistant wheat cultivars by R. cerealis infection. The TaRLCK1B protein was closely related to OsRLCK176, a rice resistance-related RLCKs-VII, with 84.03% identity. Virus-induced gene silencing plus wheat response to R. cerealis assay results indicated that silencing of TaRLCK1 impaired resistance to R. cerealis. Meantime, silencing of TaRLCK1 significantly elevated both the content of H2O2 (a major kind of reactive oxygen species, ROS) and the transcriptional level of the ROS-generating enzyme-encoding gene RBOH, but repressed the expression of the ROS-scavenging enzyme-encoding gene CAT1 at 18 hours after inoculation (hai) with R. cerealis. Taken together, these data suggested that TaRLCK1B was required for the early immune response of wheat to R. cerealis through modulating ROS signaling in wheat.

Co-regulation of Auxin and Cytokinin in Anthocyanin Accumulation During Natural Development of Purple Wheat Grains

Purple-colored wheat is a kind of wheat with purple-colored grains that contain significant levels of anthocyanins, and anthocyanins benefit human health because of their antioxidant activities. Many studies indicated stresses can significantly induce anthocyanin accumulation during grain development. However, the effects of auxins and cytokinins (CKs) on anthocyanin accumulation during purple grain development have been poorly investigated. Here, we explored the relationships of endogenous auxins and CKs with anthocyanin accumulation during the natural development of purple wheat grains. We found dynamic change of auxin content was consistent with anthocyanin accumulation trend during seed development, which began to rapidly increase from 25 dpa up to the maximum level at 35 dpa. Conversely, CKs, including iPR, cZ, czR, tZ, and tZR, significantly decreased at 25 dpa. The relative expression of GzPIN1, GzLAX3, GzIAA12, GzABP1, GzZOG2, GzUGT, and GzCKX2 was assessed, which is in agreement with ABA and CK accumulation. The findings indicated that auxins and CKs were involved in anthocyanin accumulation during purple grain development in an antagonistic manner. Meanwhile, the contents of the antioxidant enzymes POD and CAT were consistent with the dynamic change in the anthocyanin accumulation rate, which implied that ROS signaling participates in the regulation of anthocyanin accumulation.

Overexpression of <italic>TaJRL53 </italic>enhances the <italic>Fusarium </italic>head blight resistance in wheat

<p indent=0mm>Jacalin-related lectins (JRLs) are a group of plant lectins with jacalin protein domain, which play important roles during plant response to biotic and abiotic stress. According their carbohydrate binding specificities, the JRLs were described as two types: galactose-binding acalins (gJRLs) and mannose-binding jacalins (mJRLs). Previous studies have shown that <italic>TaJRL53</italic> encodes a protein with Jacalin and Dirigent domains and can be up-regulated by <italic>Fusarium graminearum</italic> infection. Wheat FHB induced by this pathogen is a disastrous disease, which not only reduces the grain yield, but also contains deoxynivalenol and other toxins, which seriously affect the health of human and livestock. To dissect the gene’s function in FHB resistance, we silenced and overexpressed the <italic>TaJRL53</italic> in wheat respectively. As a result, attenuating <italic>TaJRL53</italic> increased susceptibility to <italic>Fusarium graminearum</italic>. And susceptible wheat transformed with <italic>TaJRL53</italic> over-expression showed higher <italic>Fusarium</italic> head blight resistance, the number of diseased spikelets (NDS) and length of diseased spike rachis (LDR) of transgenics wheat with <italic>TaJRL53</italic> overexpression were significantly reduced than those of wild type. After <italic>Fusarium graminearum</italic> infection, the expression of ROS synthesis pathway, JA synthesis and signaling pathways marker genes, and disease related genes in <italic>TaJRL53</italic> over-expression transgenic plants were higher than those in non-transgenic control. These results suggest that <italic>TaJRL53</italic> enhanced the FHB resistance in wheat through regulating ROS synthesis pathway and JA signal transduction pathways. This study enhanced the understanding of wheat JRLs family genes’ function and laid a foundation for the mechanism dissection of <italic>TaJRL53</italic> resistant to FHB in wheat.

Proteomics and phosphoproteomics revealed molecular networks of stomatal immune responses.

Dynamic protein and phosphoprotein profiles uncovered the overall regulation of stomata movement against pathogen invasion and phosphorylation states of proteins involved in ABA, SA, calcium and ROS signaling, which may modulate the stomatal immune response. Stomatal openings represent a major route of pathogen entry into the plant, and plants have evolved mechanisms to regulate stomatal aperture as innate immune response against bacterial invasion. However, the mechanisms underlying stomatal immunity are not fully understood. Taking advantage of high-throughput liquid chromatography mass spectrometry (LC-MS), we performed label-free proteomic and phosphoproteomic analyses of enriched guard cells in response to a bacterial pathogen Pseudomonas syringae pv. tomato (Pst) DC3000. In total, 495 proteins and 1229 phosphoproteins were identified as differentially regulated. These proteins are involved in a variety of signaling pathways, including abscisic acid and salicylic acid hormone signaling, calcium and reactive oxygen species signaling. We also showed that dynamic changes of phosphoprotein WRKY transcription factors may play a crucial role in regulating stomata movement in plant immunity. The identified proteins/phosphoproteins and the pathways form interactive molecular networks to regulate stomatal immunity. This study has provided new insights into the multifaceted mechanisms of stomatal immunity. The differential proteins and phosphoproteins are potential targets for engineering or breeding of crops for enhanced pathogen defense.

Lysophosphatidic acid receptor 5 transactivation of TGFBR1 stimulates the mRNA expression of proteoglycan synthesizing genes XYLT1 and CHST3

Lysophosphatidic acid (LPA) via transactivation dependent signalling pathways contributes to a plethora of physiological and pathophysiological responses. In the vasculature, hyperelongation of glycosaminoglycan (GAG) chains on proteoglycans leads to lipid retention in the intima resulting in the early pathogenesis of atherosclerosis. Therefore, we investigated and defined the contribution of transactivation dependent signalling in LPA mediated GAG chain hyperelongation in human vascular smooth muscle cells (VSMCs).LPA acting via the LPA receptor 5 (LPAR5) transactivates the TGFBR1 to stimulate the mRNA expression of GAG initiation and elongation genes xylosyltransferase-1 (XYLT1) and chondroitin 6-sulfotransferase-1 (CHST3), respectively. We found that LPA stimulates ROS and Akt signalling in VSMCs, however they are not associated in LPAR5 transactivation of the TGFBR1. We observed that LPA via ROCK dependent pathways transactivates the TGFBR1 to stimulate genes associated with GAG chain elongation. We demonstrate that GPCR transactivation of the TGFBR1 occurs via a universal biochemical mechanism and the identified effectors represent potential therapeutic targets to inhibit pathophysiological effects of GPCR transactivation of the TGFBR1.

Mitochondria Targeted Viral Replication and Survival Strategies-Prospective on SARS-CoV-2.

SARS-CoV-2 is a positive sense RNA coronavirus that constitutes a new threat for the global community and economy. While vaccines against SARS-CoV-2 are being developed, the mechanisms through which this virus takes control of an infected cell to replicate remains poorly understood. Upon infection, viruses completely rely on host cell molecular machinery to survive and replicate. To escape from the immune response and proliferate, viruses strategically modulate cellular metabolism and alter subcellular organelle architecture and functions. One way they do this is by modulating the structure and function of mitochondria, a critical cellular metabolic hub but also a key platform for the regulation of cellular immunity. This versatile nature of mitochondria defends host cells from viruses through several mechanisms including cellular apoptosis, ROS signaling, MAVS activation and mitochondrial DNA-dependent immune activation. These events are regulated by mitochondrial dynamics, a process by which mitochondria alter their structure (including their length and connectivity) in response to stress or other cues. It is therefore not surprising that viruses, including coronaviruses hijack these processes for their survival. In this review, we highlight how positive sense RNA viruses modulate mitochondrial dynamics and metabolism to evade mitochondrial mediated immune response in order to proliferate.

Abstract 539: Buthionine Sulfoximine (BSO) Prevents Reductive Stress-induced Pathological Hypertrophic Cardiomyopathy

Background: Chronic reductive stress (RS) induces pathological cardiac remodeling and diastolic dysfunction. Here, we hypothesized that preventing RS via glutathione (GSH) depletion, through selective inhibition of γ-glutamyl cysteine ligase (γGCL), mitigates cardiac pathology in cRS mice. Methods: Cardiac-specific constitutively active Nrf2 TG-mice (α-MHc-caNrf2-TG), at 6 weeks of age, were administered with buthionine sulfoximine (BSO; 5.0 mM/Kg; daily for 16-weeks). At the end of 22 weeks, cardiac structure and function (systole &amp; diastole using echocardiography), myocardial redox state, levels of ROS (using dihydroethidium (DHE) fluorescence), and antioxidant proteome were assessed in TG mice treated with PBS or BSO and compared with the age matched NTG littermates (n=6/group). Results: While the TG mice experiencing RS (GSH; 426.3±22.55 vs. 141.8±3.9 &amp; GSH/GSSG; 61.04±5.4 vs. 23.27±1.3 in TG vs. NTG), this was significantly curtailed in BSO-treated TG mice (GSH 161.8±12.6 &amp; GSH/GSSG; 25.1±4.3). This was coupled with the normal cardiac functions (EF; ~53% &amp; MV E/A; 1.57) in the BSO-treated TG when compared to TG mice experiencing a hyper systolic function (&gt;80% ejection fraction) with decreased cardiac volume and diastolic dysfunction with restricted filling (MV E/A ratio; &gt;3.0), Of note, BSO treatment did not alter the protein levels of antioxidants (i.e. GCLC, GCLM, NQO1 and CAT), but only depleted the GSH pool (via inhibiting GCL activity) and restored the basal ROS signaling in the myocardium. Moreover, the BSO-treated TG mice did not develop cardiac hypertrophy, which was assessed by heart weight/body weight ratio, qPCR-based gene expression for hypertrophy ( Anf, Bnf, α-MHc and β-Mhc ). Conclusion: Our results suggest that pharmacological manipulation of myocardial redox and repletion of basal ROS signaling prevented RS-mediated pathological processes and rescued the cardiac structure and function.

CO2 Elevation Accelerates Phenology and Alters Carbon/Nitrogen Metabolism vis-à-vis ROS Abundance in Bread Wheat.

Wheat is an important staple food crop of the world and it accounts for 18–20% of human dietary protein. Recent reports suggest that CO2 elevation (CE) reduces grain protein and micronutrient content. In our earlier study, it was found that the enhanced production of nitric oxide (NO) and the concomitant decrease in transcript abundance as well as activity of nitrate reductase (NR) and high affinity nitrate transporters (HATS) resulted in CE-mediated decrease in N metabolites in wheat seedlings. In the current study, two bread wheat genotypes Gluyas Early and B.T. Schomburgk differing in nitrate uptake and assimilation properties were evaluated for their response to CE. To understand the impact of low (LN), optimal (ON) and high (HN) nitrogen supply on plant growth, phenology, N and C metabolism, ROS and RNS signaling and yield, plants were evaluated under short term (hydroponics experiment) and long term (pot experiment) CE. CE improved growth, altered N assimilation, C/N ratio, N use efficiency (NUE) in B.T. Schomburgk. In general, CE decreased shoot N concentration and grain protein concentration in wheat irrespective of N supply. CE accelerated phenology and resulted in early flowering of both the wheat genotypes. Plants grown under CE showed higher levels of nitrosothiol and ROS, mainly under optimal and high nitrogen supply. Photorespiratory ammonia assimilating genes were down regulated by CE, whereas, expression of nitrate transporter/NPF genes were differentially regulated between genotypes by CE under different N availability. The response to CE was dependent on N supply as well as genotype. Hence, N fertilizer recommendation needs to be revised based on these variables for improving plant responses to N fertilization under a future CE scenario.

Cross-talk between gama-aminobutyric acid and calcium ion regulates lipid biosynthesis in Monoraphidium sp. QLY-1 in response to combined treatment of fulvic acid and salinity stress

In this study, the cross-talk between gama-aminobutyric acid (GABA) and calcium ion (Ca2+) signalling in the regulation of lipid production and cell growth in microalgae under fulvic acid and salinity stress (FA-salinity treatment) was investigated. GABA enhanced the lipid content and lipid productivity rate considerably, which were 1.27 and 1.29 times higher than those of the control, respectively. The levels of biosynthetic gene transcription, GSH, Ca2+ and cellular GABA were promoted by GABA addition, but decreased the ROS levels. Furthermore, the application of Ca2+ also increased lipid synthesis by regulating ROS and GABA signalling and lipogenesis-related genes. These results indicated that cytosolic GABA and Ca2+ levels exert crucial cross-talk in the modulation of cell growth and lipid accumulation induced by FA-salinity treatment. Collectively, this study demonstrated the beneficial effects caused by induction of the combination of chemical compounds on lipid production and provided new insights into lipid synthesis in microalgae.

Alpha lipoic acid promotes development of hematopoietic progenitors derived from human embryonic stem cells by antagonizing ROS signals.

Antagonism of ROS signaling can inhibit cell apoptosis and autophagy, thus favoring the maintenance and expansion of hematopoietic stem cells. Alpha lipoic acid (ALA), a small antioxidant molecule, affects cell apoptosis by lowering the ROS level. In this study, we show that ALA promoted production of human pluripotent stem cells (hPSCs) derived hemogenic endothelial cells and hematopoietic stem/progenitor cells in vitro. Transcriptome analysis of hPSCs derived hemogenic endothelial cells showed that ALA promoted endothelial‐to‐hematopoietic transition by up‐regulating RUNX1, GFI1, GFI1B, MEIS2, and HIF1A and down‐regulating SOX17, TGFB1, TGFB2, TGFB3, TGFBR1, and TGFBR2. ALA also up‐regulated sensor genes of ROS signals, including HIF1A, FOXO1, FOXO3, ATM, PETEN, SIRT1, and SIRT3, during the process of hPSCs derived hemogenic endothelial cells generation. However, in more mature hPSC‐derived hematopoietic stem/progenitor cells, ALA reduced ROS levels and inhibited apoptosis. In particular, ALA enhanced development of hPSCs derived hematopoietic stem/progenitor cells by up‐regulating HIF1A in response to a hypoxic environment. Furthermore, addition of ALA in ex vivo culture greatly improved the maintenance of functional cord blood HSCs by in vivo transplantation assay. Our findings support the conjecture that ALA plays an important role in efficient regeneration of hematopoietic stem/progenitor cells from hPSCs and maintenance of functional HSCs, providing insight into understanding of regeneration of early hematopoiesis for engineering clinically useful hPSCs derived hematopoietic stem/progenitor cells transplantation. Thus, ALA can be used in the study of hPSCs derived HSCs.

Danger-Associated Peptide Regulates Root Immune Responses and Root Growth by Affecting ROS Formation in Arabidopsis.

Plant elicitor peptides (Peps) are damage/danger-associated molecular patterns (DAMPs) that are perceived by a pair of receptor-like kinases, PEPR1 and PEPR2, to enhance innate immunity and induce the growth inhibition of root in Arabidopsis thaliana. In this study, we show that PEPR1 and PEPR2 function vitally in roots to regulate the root immune responses when treating the roots with bacterial pathogen Pst DC3000. PEPR2, rather than PEPR1, played a predominant role in the perception of Pep1 in the roots and further triggered a strong ROS accumulation—the substance acts as an antimicrobial agent or as a secondary messenger in plant cells. Consistently, seedlings mutating two major ROS-generating enzyme genes, respiratory burst oxidase homologs D and F (RBOHD and RBOHF), abolished the root ROS accumulation and impaired the growth inhibition of the roots induced by Pep1. Furthermore, we revealed that botrytis-induced kinase 1 (BIK1) physically interacted with PEPRs and RBOHD/F, respectively, and served downstream of the Pep1-PEPRs signaling pathway to regulate Pep1-induced ROS production and root growth inhibition. In conclusion, this study demonstrates a previously unrecognized signaling crosstalk between Pep1 and ROS signaling to regulate root immune response and root growth.

Understanding the early cold response mechanism in IR64 indica rice variety through comparative transcriptome analysis

BackgroundCellular reprogramming in response to environmental stress involves alteration of gene expression, changes in the protein and metabolite profile for ensuring better stress management in plants. Similar to other plant species originating in tropical and sub-tropical areas, indica rice is highly sensitive to low temperature that adversely affects its growth and grain productivity. Substantial work has been done to understand cold induced changes in gene expression in rice plants. However, adequate information is not available for early gene expression, especially in indica variety. Therefore, a transcriptome profile was generated for cold shock treated seedlings of IR64 variety to identify early responsive genes.ResultsThe functional annotation of early DEGs shows enrichment of genes involved in altered membrane rigidity and electrolytic leakage, the onset of calcium signaling, ROS generation and activation of stress responsive transcription factors in IR64. Gene regulatory network suggests that cold shock induced Ca2+ signaling activates DREB/CBF pathway and other groups of transcription factors such as MYB, NAC and ZFP; for activating various cold-responsive genes. The analysis also indicates that cold induced signaling proteins like RLKs, RLCKs, CDPKs and MAPKK and ROS signaling proteins. Further, several late-embryogenesis-abundant (LEA), dehydrins and low temperature-induced-genes were upregulated under early cold shock condition, indicating the onset of water-deficit conditions. Expression profiling in different high yielding cultivars shows high expression of cold-responsive genes in Heera and CB1 indica varieties. These varieties show low levels of cold induced ROS production, electrolytic leakage and high germination rate post-cold stress, compared to IR36 and IR64. Collectively, these results suggest that these varieties may have improved adaptability to cold stress.ConclusionsThe results of this study provide insights about early responsive events in Oryza sativa l.ssp. indica cv IR64 in response to cold stress. Our data shows the onset of cold response is associated with upregulation of stress responsive TFs, hydrophilic proteins and signaling molecules, whereas, the genes coding for cellular biosynthetic enzymes, cell cycle control and growth-related TFs are downregulated. This study reports that the generation of ROS is integral to the early response to trigger the ROS mediated signaling events during later stages.

Melatonin improves rice salinity stress tolerance by NADPH oxidase-dependent control of the plasma membrane K+ transporters and K+ homeostasis.

This study aimed to reveal the mechanistic basis of the melatonin-mediated amelioration of salinity stress in plants. Electrophysiological experiments revealed that melatonin decreased salt-induced K+ efflux (a critical determinant of plant salt tolerance) in a dose- and time-dependent manner and reduced sensitivity of the plasma membrane K+ -permeable channels to hydroxyl radicals. These beneficial effects of melatonin were abolished by NADPH oxidase blocker DPI. Transcriptome analyses revealed that melatonin induced 585 (448 up- and 137 down-regulated) and 59 (54 up- and 5 down-regulated) differentially expressed genes (DEGs) in the root tip and mature zone, respectively. The most noticeable changes in the root tip were melatonin-induced increase in the expression of several DEGs encoding respiratory burst NADPH oxidases (OsRBOHA and OsRBOHF), calcineurin B-like/calcineurin B-like-interacting protein kinase (OsCBL/OsCIPK), and calcium-dependent protein kinase (OsCDPK) under salt stress. Melatonin also enhanced the expression of potassium transporter genes (OsAKT1, OsHAK1, and OsHAK5). Taken together, these results indicate that melatonin improves salt tolerance in rice by enabling K+ retention in roots, and that the latter process is conferred by melatonin scavenging of hydroxyl radicals and a concurrent OsRBOHF-dependent ROS signalling required to activate stress-responsive genes and increase the expression of K+ uptake transporters in the root tip.

Antagonistic Pleiotropy in Mitochondria ROS Signaling Responses to Manganese

SUMMARY Antagonistic pleiotropy refers to opposing beneficial and adverse signaling by a single agent. Understanding opposing signaling is important because pathologic outcome can result from adverse causative agents or failure of beneficial mechanisms. To test for opposing responses at a systems level, we used a transcriptome-metabolome-wide association study (TMWAS) with the rationale that metabolite changes provide a phenotypic readout of gene expression, and gene expression provides a phenotypic readout of signaling metabolites. We incorporated measures of mitochondrial oxidative stress (mtOx) and oxygen consumption rate (mtOCR) with TMWAS of cells with varied manganese (Mn) concentration and found that adverse neuroinflammatory signaling and fatty acid metabolism were connected to mtOx while beneficial ion transport and neurotransmitter metabolism were connected to mtOCR. Each community contained opposing transcriptome-metabolome interactions, which were linked to biologic functions. The results show that antagonistic pleiotropy is a generalized cell systems response to mitochondrial ROS signaling.

Role of Endoplasmic Reticulum Stress Sensor IRE1α in Cellular Physiology, Calcium, ROS Signaling, and Metaflammation.

Inositol-requiring transmembrane kinase endoribonuclease-1α (IRE1α) is the most prominent and evolutionarily conserved unfolded protein response (UPR) signal transducer during endoplasmic reticulum functional upset (ER stress). A IRE1α signal pathway arbitrates yin and yang of cellular fate in objectionable conditions. It plays several roles in fundamental cellular physiology as well as in several pathological conditions such as diabetes, obesity, inflammation, cancer, neurodegeneration, and in many other diseases. Thus, further understanding of its molecular structure and mechanism of action during different cell insults helps in designing and developing better therapeutic strategies for the above-mentioned chronic diseases. In this review, recent insights into structure and mechanism of activation of IRE1α along with its complex regulating network were discussed in relation to their basic cellular physiological function. Addressing different binding partners that can modulate IRE1α function, UPRosome triggers different downstream pathways depending on the cellular backdrop. Furthermore, IRE1α are in normal cell activities outside the dominion of ER stress and activities under the weather of inflammation, diabetes, and obesity-related metaflammation. Thus, IRE1 as an ER stress sensor needs to be understood from a wider perspective for comprehensive functional meaning, which facilitates us with assembling future needs and therapeutic benefits.

Expansin-like Exl1 from Pectobacterium is a virulence factor required for host infection, and induces a defence plant response involving ROS, and jasmonate, ethylene and salicylic acid signalling pathways in Arabidopsis thaliana

Expansins are encoded by some phytopathogenic bacteria and evidence indicates that they act as virulence factors for host infection. Here we analysed the expression of exl1 by Pectobacterium brasiliense and Pectobacterium atrosepticum. In both, exl1 gene appears to be under quorum sensing control, and protein Exl1 can be observed in culture medium and during plant infection. Expression of exl1 correlates with pathogen virulence, where symptoms are reduced in a Δexl1 mutant strain of P. atrosepticum. As well as Δexl1 exhibiting less maceration of potato plants, fewer bacteria are observed at distance from the inoculation site. However, bacteria infiltrated into the plant tissue are as virulent as the wild type, suggesting that this is due to alterations in the initial invasion of the tissue. Additionally, swarming from colonies grown on MacConkey soft agar was delayed in the mutant in comparison to the wild type. We found that Exl1 acts on the plant tissue, probably by remodelling of a cell wall component or altering the barrier properties of the cell wall inducing a plant defence response, which results in the production of ROS and the induction of marker genes of the JA, ET and SA signalling pathways in Arabidopsis thaliana. Exl1 inactive mutants fail to trigger such responses. This defence response is protective against Pectobacterium brasiliense and Botrytis cinerea in more than one plant species.

Characterization and genetic analysis of the oshpl3 rice lesion mimic mutant showing spontaneous cell death and enhanced bacterial blight resistance

Plant lesion mimic mutants have been used as ideal materials for studying pathogen defense mechanisms due to their spontaneous activation of defense responses in plants. Here, we report the identification and characterization of a rice lesion mimic mutant, oshpl3. The oshpl3 mutant initially displayed white spots on leaves of 7-day-old seedlings, and the white spots gradually turned into large brown spots during plant development, accompanied by poor metrics of major agronomic traits. Histochemical analysis showed that spontaneous cell death and H2O2 hyperaccumulation occurred in oshpl3. Defense responses were induced in the oshpl3 mutant, such as enhanced ROS signaling activated by recognition of pathogen-associated molecular patterns, and also upregulated expression of genes involved in pathogenesis and JA metabolism. These defense responses enhanced resistance to bacterial blight caused by Xanthomonas oryzae pv. oryzae. The mutated gene was identified as OsHPL3 (LOC_Os02g02000) by map-based cloning. A G1006A mutation occurred in OsHPL3, causing a G-to-D mutation of the 295th amino acid in the transmembrane region of OsHPL3. OsHPL3 localized to the chloroplast, cytoplasm, and another unknown organelle, while the mutated protein OsHPL3G295D was not obviously observed in the chloroplast, suggesting that the G295D mutation affected its chloroplast localization. Based on our findings, the G295D mutation in OsHPL3 is most likely responsible for the phenotypes of the oshpl3 mutant. Our results provide new clues for studying the function of the OsHPL3 protein.

NEK7: a potential therapy target for NLRP3-related diseases.

NLRP3 inflammasome plays an essential role in innate immunity, yet the activation mechanism of NLRP3 inflammasome is not clear. In human or animal models, inappropriate NLRP3 inflammasome activation is implicated in many NLRP3-related diseases, such as tumors, inflammatory diseases and autoimmune diseases. Until now, a great number of inhibitors have been used to disturb the related signaling pathways, such as IL-1β blockade, IL-18 blockade and caspase-1 inhibitors. Unfortunately, most of these inhibitors just disturb the signaling pathways after the activation of NLRP3 inflammasome. Inhibitors that directly regulate NLRP3 to abolish the inflammation response may be more effective. NEK7 is a multifunctional kinase affecting centrosome duplication, mitochondrial regulation, intracellular protein transport, DNA repair and mitotic spindle assembly. Researchers have made significant observations on the regulation of gene transcription or protein expression of the NLRP3 inflammasome signaling pathway by NEK7. Those signaling pathways include ROS signaling, potassium efflux, lysosomal destabilization, and NF-κB signaling. Furthermore, NEK7 has been proved to be involved in many NLRP3-related diseases in humans or in animal models. Inhibitors focused on NEK7 may regulate NLRP3 to abolish the inflammation response and NEK7 may be a potential therapeutic target for NLRP3-related diseases.

LncRNA regulates tomato fruit cracking by coordinating gene expression via a hormone-redox-cell wall network

BackgroundFruit cracking occurs easily under unsuitable environmental conditions and is one of the main types of damage that occurs in fruit production. It is widely accepted that plants have developed defence mechanisms and regulatory networks that respond to abiotic stress, which involves perceiving, integrating and responding to stress signals by modulating the expression of related genes. Fruit cracking is also a physiological disease caused by abiotic stress. It has been reported that a single or several genes may regulate fruit cracking. However, almost none of these reports have involved cracking regulatory networks.ResultsHere, RNA expression in 0 h, 8 h and 30 h saturated irrigation-treated fruits from two contrasting tomato genotypes, ‘LA1698’ (cracking-resistant, CR) and ‘LA2683’ (cracking-susceptible, CS), was analysed by mRNA and lncRNA sequencing. The GO pathways of the differentially expressed mRNAs were mainly enriched in the ‘hormone metabolic process’, ‘cell wall organization’, ‘oxidoreductase activity’ and ‘catalytic activity’ categories. According to the gene expression analysis, significantly differentially expressed genes included Solyc02g080530.3 (Peroxide, POD), Solyc01g008710.3 (Mannan endo-1,4-beta-mannosidase, MAN), Solyc08g077910.3 (Expanded, EXP), Solyc09g075330.3 (Pectinesterase, PE), Solyc07g055990.3 (Xyloglucan endotransglucosylase-hydrolase 7, XTH7), Solyc12g011030.2 (Xyloglucan endotransglucosylase-hydrolase 9, XTH9), Solyc10g080210.2 (Polygalacturonase-2, PG2), Solyc08g081010.2 (Gamma-glutamylcysteine synthetase, gamma-GCS), Solyc09g008720.2 (Ethylene receptor, ER), Solyc11g042560.2 (Ethylene-responsive transcription factor 4, ERF4) etc. In addition, the lncRNAs (XLOC_16662 and XLOC_033910, etc) regulated the expression of their neighbouring genes, and genes related to tomato cracking were selected to construct a lncRNA-mRNA network influencing tomato cracking.ConclusionsThis study provides insight into the responsive network for water-induced cracking in tomato fruit. Specifically, lncRNAs regulate the hormone-redox-cell wall network, including plant hormone (auxin, ethylene) and ROS (H2O2) signal transduction and many cell wall-related mRNAs (EXP, PG, XTH), as well as some lncRNAs (XLOC_16662 and XLOC_033910, etc.).

The RNA-seq transcriptomic analysis reveals genes mediating salt tolerance through rapid triggering of ion transporters in a mutant barley.

Considering the complex nature of salinity tolerance mechanisms, the use of isogenic lines or mutants possessing the same genetic background albeit different tolerance to salinity is a suitable method for reduction of analytical complexity to study these mechanisms. In the present study, whole transcriptome analysis was evaluated using RNA-seq method between a salt-tolerant mutant line “M4-73-30” and its wild-type “Zarjou” cultivar at seedling stage after six hours of exposure to salt stress (300 mM NaCl). Transcriptome sequencing yielded 20 million reads for each genotype. A total number of 7116 transcripts with differential expression were identified, 1586 and 1479 of which were obtained with significantly increased expression in the mutant and the wild-type, respectively. In addition, the families of WRKY, ERF, AP2/EREBP, NAC, CTR/DRE, AP2/ERF, MAD, MIKC, HSF, and bZIP were identified as the important transcription factors with specific expression in the mutant genotype. The RNA-seq results were confirmed at several time points using qRT-PCR for some important salt-responsive genes. In general, the results revealed that the mutant accumulated higher levels of sodium ion in the root and decreased its transfer to the shoot. Also, the mutant increased the amount of potassium ion leading to the maintenance a high ratio [K+]/[Na+] in the shoot compared to its wild-type via fast stomata closure and consequently transpiration reduction under the salt stress. Moreover, a reduction in photosynthesis and respiration was observed in the mutant, resulting in utilization of the stored energy and the carbon for maintaining the plant tissues, which is considered as a mechanism of salt tolerance in plants. Up-regulation of catalase, peroxidase, and ascorbate peroxidase genes has resulted in higher accumulation of H2O2 in the wild-type compared to the mutant. Therefore, the wild-type initiated rapid ROS signals which led to less oxidative scavenging in comparison with the mutant. The mutant increased expression in the ion transporters and the channels related to the salinity to maintain the ion homeostasis. In overall, the results demonstrated that the mutant responded better to the salt stress under both osmotic and ionic stress phases and lower damage was observed in the mutant compared to its wild-type under the salt stress.