Functionality of Reactive Oxygen Species (ROS) in Plants: Toxicity and Control in Poaceae Crops Exposed to Abiotic Stress.

Agriculture and changing environmental conditions are closely related, as weather changes could adversely affect living organisms or regions of crop cultivation. Changing environmental conditions trigger different abiotic stresses, which ultimately cause the accumulation of reactive oxygen species (ROS) in plants. Common ROS production sites are the chloroplast, endoplasmic reticulum, plasma membrane, mitochondria, peroxisomes, etc. The imbalance in ROS production and ROS detoxification in plant cells leads to oxidative damage to biomolecules such as lipids, nucleic acids, and proteins. At low concentrations, ROS initiates signaling events related to development and adaptations to abiotic stress in plants by inducing signal transduction pathways. In plants, a stress signal is perceived by various receptors that induce a signal transduction pathway that activates numerous signaling networks, which disrupt gene expression, impair the diversity of kinase/phosphatase signaling cascades that manage the stress response in the plant, and result in changes in physiological responses under various stresses. ROS production also regulates ABA-dependent and ABA-independent pathways to mitigate drought stress. This review focuses on the common subcellular location of manufacturing, complex signaling mechanisms, and networks of ROS, with an emphasis on cellular effects and enzymatic and non-enzymatic antioxidant scavenging mechanisms of ROS in Poaceae crops against drought stress and how the manipulation of ROS regulates stress tolerance in plants. Understanding ROS systems in plants could help to create innovative strategies to evolve paths of cell protection against the negative effects of excessive ROS in attempts to improve crop productivity in adverse environments.

Transcriptional networks revealed late embryogenesis abundant genes regulating drought mitigation in aromatic Keteki Joha rice.

Climate change has become increasingly intertwined with the occurrence and severity of droughts. As global temperatures rise due to greenhouse gas emissions, weather patterns are altered, leading to shifts in precipitation levels and distribution. These exacerbate the risk of drought in many regions, with potentially devastating consequences. A comprehensive transcriptome analysis was performed on Keteki Joha, an aromatic rice from North East India, with the aim of elucidating molecular responses to drought. Numerous genes linked to drought were activated, with both ABA-dependent and ABA-independent pathways playing crucial roles. Upregulated genes were enriched with gene ontology terms with response to abscisic acid and abscisic acid-activated signalling pathway, suggesting the existence of an ABA-dependent pathway for drought mitigation. The upregulated genes were also enriched with responses to stress, water, heat, jasmonic acid, and hydrogen peroxide, indicating the presence of an ABA-independent pathway alongside the ABA-dependent mechanism. Weighted Correlation Network Analysis (WGCNA) identified 267 genes that specifically govern drought mitigation in Keteki Joha. The late embryogenesis abundant (LEA) gene family emerges as the most overrepresented in both RNA sequencing data and WGCNA analysis, suggesting their dominant role in mitigating drought. Notably, 31 LEA genes were induced in seedlings and 32 in mature stages under drought stress. The LEA3-1, LEA14/WSI18, RAB16A, RAB16B, DHN1, DHN6, LEA1, LEA3, LEA17, and LEA33 exhibited and established co-expression with numerous other drought stress-related genes, indicating their inseparable role in alleviating drought. Consequently, LEA genes have been proposed to be primary and crucial responders to drought in Keteki Joha.

Genome-wide identification and expression analysis of the Pisum sativum (L.) APETALA2/ethylene-responsive factor (AP2/ERF) gene family reveals functions in drought and cold stresses.

AP2/ERF (APETALA2/Ethylene Response Factor) is a family of transcription factors that play essential roles in regulating gene expression in response to various environmental stimuli, including biotic and abiotic stresses, hormone signaling, and developmental processes. Pisum sativum (L.), commonly known as garden pea, is a winter crop sensitive to high temperatures and can also be affected by extreme cold and drought conditions. This study performed a genome-wide analysis of AP2/ERF genes and identified 153 AP2/ERF genes in P. sativum. Based on the conserved AP2/ERF domain and sequence homology, they were classified into AP2 (APETALA2), ERF (Ethylene Response Factor), DREB (Dehydration responsive element-binding), RAV (Related to Abscisic Acid Insensitive 3/ Viviparous 1) and Soloist subfamily. The DREB and ERF subfamily were further divided into groups A1-6 and B1-B6. Tandem and segmental duplication events were more frequent in the ERF subfamily, which can have important implications for their evolution and functional diversification. Under cold stress, the expression of DREB1A was highly induced in leaves, whereas DREB1B was suppressed. Similarly, the DREB2A, DREB2C, DREB2E, and DREB2F were induced in leaves under drought stress. The putative target genes of AP2/ERF transcription factors are highly diversified, suggesting that they play essential roles in various physiological responses in plants, including responses to biotic and abiotic stresses as well as developmental processes. Thus, this study of AP2/ERF genes and their functions provides valuable insight into how P. sativum responds to different environmental conditions, including cold and drought stresses.

Role of long non coding RNA in plants under abiotic and biotic stresses.

Evolutionary processes have evolved plants to cope with several different natural stresses. Basic physiological activities of crop plants are significantly harmed by these stresses, reducing productivity and eventually leading to death. The recent advancements in high-throughput sequencing of transcriptome and expression profiling with NGS techniques lead to the innovation of various RNAs which do not code for proteins, more specifically long non-coding RNAs (lncRNAs), undergirding regulate growth, development, and the plant defence mechanism transcriptionally under stress situations. LncRNAs are a diverse set of RNAs that play key roles in various biological processes at the level of transcription, post-transcription, and epigenetics. These are thought to serve crucial functions in plant immunity and response to changes in the environment. In plants, however, just a few lncRNAs have been functionally identified. In this review, we will address recent advancements in comprehending lncRNA regulatory functions, focusing on the expanding involvement of lncRNAs in modulating environmental stress responsiveness in plants.

Quantitative Analysis of Redox Pool (NAD + , NADH Content) in Plant Samples Under Aluminum Stress.

Nicotinamide adenine dinucleotide (NAD) is an essential cofactor of numerous enzymatic reactions found in all living cells. Pyridine nucleotides (NAD + and NADH) are also key players in signaling through reactive oxygen species (ROS), being crucial in the regulation of both ROS-producing and ROS-consuming systems in plants. NAD content is a powerful modulator of metabolic integration, protein de-acetylation, and DNA repair. The balance between NAD oxidized and reduced forms, i.e ., the NADH/NAD + ratio, indicates the redox state of a cell, and it is a measurement that reflects the metabolic health of cells. Here we present an easy method to estimate the NAD + and NADH content enzymatically, using alcohol dehydrogenase (ADH), an oxido-reductase enzyme, and with MTT (3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) as the substrate and 1-methoxy PMS (1-Methoxy-5-methylphenazinium methyl sulfate) as the electron carrier. MTT is reduced to a purple formazan, which is then detected. We used Arabidopsis leaf samples exposed to aluminum toxicity and under untreated control conditions. NADH/NAD + connects many aspects of metabolism and plays vital roles in plant developmental processes and stress responses. Therefore, it is fundamental to determine the status of NADH/NAD + under stress.

Safety Evaluation of Oleoresin-Based Turmeric Formulation: Assessment of Genotoxicity and Acute and Subchronic Oral Toxicity.

Turmeric rhizome (Curcuma longa L.) has been used without concern for safety as a culinary spice and traditional medicine under the ancient Ayurvedic medicinal system of India dating back nearly 4000 years. This preclinical safety evaluation was done to determine the safety of an oleoresin-based turmeric extract (CURCUGEN®). Guidelines from the Organization for Economic Co-operation and Development (OECD) directed the assessment of safety for the in vitro and in vivo application of CURCUGEN®. Safety of the herbal medicine was evaluated through the toxicological assessment of acute, oral, and 90-day repeated dosing, genotoxicity, and mutagenicity study. Genotoxicity tests included the in vitro bacterial reverse mutation test, chromosomal aberration test, and in vivo micronucleus test. The single dose of CURCUGEN® administered orally (gavage) to Sprague-Dawley (SD) rats resulted in a LD50 of >5000 mg/kg body weight. The subchronic assessment of CURCUGEN®, as administered to SD rats over 90 days resulted in a no observed adverse effect level (NOAEL) of 2000 mg/kg body weight/day. CURCUGEN® did not elicit any genotoxic or clastogenic effect in genotoxicity tests. The battery of safety studies carried out demonstrated that CURCUGEN® showed no evidence of general toxicity or genotoxicity.

Transcriptomic Analysis Revealed Reactive Oxygen Species Scavenging Mechanisms Associated With Ferrous Iron Toxicity in Aromatic Keteki Joha Rice.

Lowland acidic soils with water-logged regions are often affected by ferrous iron (Fe2+) toxicity, a major yield-limiting factor of rice production. Under severe Fe2+ toxicity, reactive oxygen species (ROS) are crucial, although molecular mechanisms and associated ROS homeostasis genes are still unknown. In this study, a comparative RNA-Seq based transcriptome analysis was conducted to understand the Fe2+ toxicity tolerance mechanism in aromatic Keteki Joha. About 69 Fe homeostasis related genes and their homologs were identified, where most of the genes were downregulated. Under severe Fe2+ toxicity, the biosynthesis of amino acids, RNA degradation, and glutathione metabolism were induced, whereas phenylpropanoid biosynthesis, photosynthesis, and fatty acid elongation were inhibited. The mitochondrial iron transporter (OsMIT), vacuolar iron transporter 2 (OsVIT2), ferritin (OsFER), vacuolar mugineic acid transporter (OsVMT), phenolic efflux zero1 (OsPEZ1), root meander curling (OsRMC), and nicotianamine synthase (OsNAS3) were upregulated in different tissues, suggesting the importance of Fe retention and sequestration for detoxification. However, several antioxidants, ROS scavenging genes and abiotic stress-responsive transcription factors indicate ROS homeostasis as one of the most important defense mechanisms under severe Fe2+ toxicity. Catalase (CAT), glutathione (GSH), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were upregulated. Moreover, abiotic stress-responsive transcription factors, no apical meristem (NAC), myeloblastosis (MYB), auxin response factor (ARF), basic helix-loop-helix (bZIP), WRKY, and C2H2-zinc finger protein (C2H2-ZFP) were also upregulated. Accordingly, ROS homeostasis has been proposed as an essential defense mechanism under such conditions. Thus, the current study may enrich the understanding of Fe-homeostasis in rice.

The enhanced bioavailability of free curcumin and bioactive-metabolite tetrahydrocurcumin from a dispersible, oleoresin-based turmeric formulation.

BACKGROUND: Curcuminoids have been widely studied for human health and disease applications, yet bioavailability remains a hurdle to actualizing all the benefits ascribed to them. The lack of standardization in analysis method, confusion about what constitutes an ideal analyte, and conflicting thoughts around dosing strategies have made it difficult to draw parity between bioavailability and bioactivity and establish a baseline for formulation comparisons. METHODS: This randomized double-blinded, 2-way cross over, single oral dose, comparative bioavailability study differentially evaluates curcumin at the time of its absorption and along various biotransformation pathways, to include free curcumin, the readily usable form of curcumin; individual and composite totals of curcumin and its analogues as exogenously cleaved conjugates, for example, total curcumin, total demethoxycurcumin (DMC), total bisdemethoxycurcumin (BDMC), and total curcuminoids respectively; and the bioactive metabolite of curcumin, total tetrahydrocurcumin (THC). As a primary study objective, the relative bioavailability of CURCUGEN, a novel dispersible, 50% curcuminoids-concentrated turmeric extract was compared to the standard curcumin reference product, curcuminoids 95% standardized extract (C-95), using the maximum concentration (Cmax), and area under the curve (AUC0-t) of free curcumin, total curcumin, total DMC, total BDMC and the curcumin active metabolite, as total THC. RESULTS: The evaluation of free curcumin demonstrated that the Cmax and AUC0-t of the CURCUGEN was 16.1 times and 39 times higher than the Cmax and AUC0-t of C-95. Furthermore, total curcumin, total DMC, total BDMC, and total curcuminoids resulted in AUC0-t of the CURCUGEN at 49.5-, 43.5-, 46.8-, and 52.5-fold higher than C-95, respectively. The relative bioavailability of CURCUGEN for total THC was found to be 31 times higher when compared to C-95. CONCLUSION: As the first human pharmacokinetics study to apply best-practice recommendations and pharmaceutically-aligned guidance in the comprehensive evaluation of a novel curcuminoids formulation, we have established the novelty of said formulation while better standardizing for the common variances and discrepancies between curcuminoids and their derivatives in the literature and commercial marketing, alike.

Tissue-Dependent Variation Profiles of Tea Quality-Related Metabolites in New Shoots of Tea Accessions.

Several metabolites define tea quality in new tea shoots composed of leaf and stem. To improve tea quality for breeding, it is important to understand the tissue-dependent genetic mechanisms and metabolic network responsible for the profile of tea quality-related metabolites. We analyzed the volatiles and specialized metabolites as the tea quality-related metabolites in leaves and stems of new shoots in 30 tea accessions to understand the tissue variation and network between tea quality-related metabolites. Our results provided the tissue-dependent variation network in the tea quality-related metabolites, including volatiles in new leaves and stems in tea accessions. Each volatile content in tea accessions showed the coefficient of variation ranging from 58.7 to 221.9% and 54.2 to 318.3% in new leaves and new stems, respectively. The accumulation pattern of tea quality-related metabolites in new leaves and stems varied depending on the accession. When comparing tea genetic populations, the profile of tea quality-related metabolites of new leaves, but not new stems, was the key to distinguishing tea genetic populations by chemical indicators. We described the network between tea quality-related metabolites, especially the dense network in new leaves. These results also will provide the key information for metabolic engineering and the selection of breeding materials in tea plants based on the tea quality-related metabolites and aid in understanding their molecular mechanisms and network of metabolic variation.

Genome-wide analysis of fluoride exporter genes in plants.

Fluoride exporter genes (FEX) are known for the expulsion of cytoplasmic fluoride, thus preventing fluoride toxicity in plants. In this study, 31 FEX genes were identified across 19 plant species. Camphor Resistance (CrcB) domain was found to be present in all the identified FEX genes in plants. FEX genes were sequentially very conserved among the plants and are located mostly in chloroplast and mitochondria. The tertiary structure (3D) of AtFEX1 suggests that FEX genes of plants possess pore I and pore II, necessary for fluoride export. The TTFSGWNQ and GCLSTVSTF motifs were found to be well conserved in pore I and pore II. Phenylalanine (Phe/F) was also present in both the motifs, necessary for fluoride ions recognition and export. Cis-acting analysis in promoter sequences of plant FEX revealed several elements associated with various functions such as phytohormone signaling, integrating biotic and abiotic stress responses in plants. Prolong fluoride exposure causes necrosis in young leaves in Vigna radiata. Expression of VrFEX1 and VrFEX2 were highly induced under exogenous fluoride, thus suggesting a possible role in fluoride detoxification. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02677-z.

Comparative Transcriptomics of Lowland Rice Varieties Uncovers Novel Candidate Genes for Adaptive Iron Excess Tolerance.

Iron (Fe) toxicity is a major challenge for plant cultivation in acidic waterlogged soil environments, where lowland rice is a major staple food crop. Only few studies have addressed the molecular characterization of excess Fe tolerance in rice, and these highlight different mechanisms for Fe tolerance. Out of 16 lowland rice varieties, we identified a pair of contrasting lines, Fe-tolerant Lachit and -susceptible Hacha. The two lines differed in their physiological and morphological responses to excess Fe, including leaf growth, leaf rolling, reactive oxygen species generation and Fe and metal contents. These responses were likely due to genetic origin as they were mirrored by differential gene expression patterns, obtained through RNA sequencing, and corresponding gene ontology term enrichment in tolerant vs. susceptible lines. Thirty-five genes of the metal homeostasis category, mainly root expressed, showed differential transcriptomic profiles suggestive of an induced tolerance mechanism. Twenty-two out of these 35 metal homeostasis genes were present in selection sweep genomic regions, in breeding signatures, and/or differentiated during rice domestication. These findings suggest that Fe excess tolerance is an important trait in the domestication of lowland rice, and the identified genes may further serve to design the targeted Fe tolerance breeding of rice crops.

Expression GWAS of PGIP1 Identifies STOP1-Dependent and STOP1-Independent Regulation of PGIP1 in Aluminum Stress Signaling in Arabidopsis.

To elucidate the unknown regulatory mechanisms involved in aluminum (Al)-induced expression of POLYGALACTURONASE-INHIBITING PROTEIN 1 (PGIP1), which is one of the downstream genes of SENSITIVE TO PROTON RHIZOTOXICITY 1 (STOP1) regulating Al-tolerance genes, we conducted a genome-wide association analysis of gene expression levels (eGWAS) of PGIP1 in the shoots under Al stress using 83 Arabidopsis thaliana accessions. The eGWAS, conducted through a mixed linear model, revealed 17 suggestive SNPs across the genome having the association with the expression level variation in PGIP1. The GWAS-detected SNPs were directly located inside transcription factors and other genes involved in stress signaling, which were expressed in response to Al. These candidate genes carried different expression level and amino acid polymorphisms. Among them, three genes encoding NAC domain-containing protein 27 (NAC027), TRX superfamily protein, and R-R-type MYB protein were associated with the suppression of PGIP1 expression in their mutants, and accordingly, the system affected Al tolerance. We also found the involvement of Al-induced endogenous nitric oxide (NO) signaling, which induces NAC027 and R-R-type MYB genes to regulate PGIP1 expression. In this study, we provide genetic evidence that STOP1-independent NO signaling pathway and STOP1-dependent regulation in phosphoinositide (PI) signaling pathway are involved in the regulation of PGIP1 expression under Al stress.

Physio-biochemical and molecular assessment of Iron (Fe2+) toxicity responses in contrasting indigenous aromatic Joha rice cultivars of Assam, India.

Iron (Fe) toxicity is one of the major abiotic stresses which limits the yield of lowland rice. This study aims to investigate the physiological, biochemical, and molecular aspects of two contrasting aromatic Joha rice, viz., Keteki and Kola Joha of Assam. Oxidative damage caused due to Fe2+ toxicity was quantitatively determined. Fe2+ toxicity in the growth medium increases the level of ROS and anti-oxidative enzyme activity. Along with the aforementioned damage caused due to Fe2+ toxicity, chlorophyll content decreases in both the rice varieties. Detection of Fe3+ and Fe2+ was also conducted by Perls' Prussian and Turnbull blue method, respectively. In addition, spectrophotometric quantification of Fe2+ was determined by 2, 2'-Bipyridyl (Bpy). Above 2.5 mM, Fe2+ toxicity was found to be lethal in rice seedlings affecting their total growth and biomass. Gene expression analysis of iron-regulated transporter 1 (OsIRT1), Yellow Stripe-Like 15 (OsYSL15), and ferritin 1 (OsFer1) revealed the differential gene expression over a time period of Fe2+ toxicity. Our study suggested that the different parameters which are considered here can be helpful for the better understanding of how aromatic Joha rice performed under Fe2+ toxicity which can also help to reveal broader aspects that how gene players are involved in the iron homeostasis mechanism in Joha rice in coming future.

Comparative RNA-Seq analysis of the root revealed transcriptional regulation system for aluminum tolerance in contrasting indica rice of North East India.

Expression pattern of aluminum (Al) tolerance genes is one of the major determinants of Al avoidance/tolerance within plant cultivars. We have performed transcriptome analysis of two contrasting (Al-tolerant, Disang; Al-sensitive, Joymati) cultivars of India's North Eastern region, an indica rice diversity hotspot, on exposure to excess Al3+ treatment in acidic condition. Co-expression analysis and SNPs enrichment analysis proposed the role of both trans-acting and cis-acting polymorphisms in Al signaling in the Al-tolerant cultivar. We proposed ten major genes, including arginine decarboxylase, phytase, and beta-glucosidase aggregating factor as candidates responsible for Al tolerance based on transcriptome analysis. Al3+ stress led to changes in the alternative splicing profile of the Al-tolerant cultivar. These studies demonstrated the transcriptional variations affiliated to Al avoidance/tolerance in contrasting indica rice of North East India and provided us with several candidate genes responsible for Al tolerance.

Expression genome-wide association study identifies that phosphatidylinositol-derived signalling regulates ALUMINIUM SENSITIVE3 expression under aluminium stress in the shoots of Arabidopsis thaliana.

To identify unknown regulatory mechanisms leading to aluminium (Al)-induction of the Al tolerance gene ALS3, we conducted an expression genome-wide association study (eGWAS) for ALS3 in the shoots of 95 Arabidopsis thaliana accessions in the presence of Al. The eGWAS was conducted using a mixed linear model with 145,940 genome-wide single nucleotide polymorphisms (SNPs) and the association results were validated using reverse genetics. We found that many SNPs from the eGWAS were associated with genes related to phosphatidylinositol metabolism as well as stress signal transduction, including Ca2+signals, inter-connected in a co-expression network. Of these, PLC9, CDPK32, ANAC071, DIR1, and a hypothetical protein (AT4G10470) possessed amino acid sequence/ gene expression level polymorphisms that were significantly associated with ALS3 expression level variation. Furthermore, T-DNA insertion mutants of PLC9, CDPK32, and ANAC071 suppressed shoot ALS3 expression in the presence of Al. This study clarified the regulatory mechanisms of ALS3 expression in the shoot and provided genetic evidence of the involvement of phosphatidylinositol-derived signal transduction under Al stress.

Plant-microbe Interactions for Sustainable Agriculture in the Post-genomic Era.

Plant-microbe interactions are both symbiotic and antagonistic, and the knowledge of both these interactions is equally important for the progress of agricultural practice and produce. This review gives an insight into the recent advances that have been made in the plant-microbe interaction study in the post-genomic era and the application of those for enhancing agricultural production. Adoption of next-generation sequencing (NGS) and marker assisted selection of resistant genes in plants, equipped with cloning and recombination techniques, has progressed the techniques for the development of resistant plant varieties by leaps and bounds. Genome-wide association studies (GWAS) of both plants and microbes have made the selection of desirable traits in plants and manipulation of the genomes of both plants and microbes effortless and less time-consuming. Stress tolerance in plants has been shown to be accentuated by association of certain microorganisms with the plant, the study and application of the same have helped develop stress-resistant varieties of crops. Beneficial microbes associated with plants are being extensively used for the development of microbial consortia that can be applied directly to the plants or the soil. Next-generation sequencing approaches have made it possible to identify the function of microbes associated in the plant microbiome that are both culturable and non-culturable, thus opening up new doors and possibilities for the use of these huge resources of microbes that can have a potential impact on agriculture.

Chelators of iron and their role in plant's iron management.

Proper transport of metal and their homeostasis is very crucial for the growth and development of plants. Plants root are the primary organs which comes in contact with the stress and thus few modifications occurs, often determining the nutrient efficiency or sometimes as a stress tolerance mechanism. Plant utilizes two strategies for the uptake of iron viz, strategy I-reduction based and strategy II-chelation based. In this review we attempted for a better understanding of how the chelators acts in the mechanism of iron uptake from soils to plants and how iron is distributed in the plants.

A Randomized Double-Blind Placebo-Control Study to Assess the Efficacy and Safety of OLNP-05 Versus Placebo for the Treatment of Subjects with Premature Ejaculation.

Premature ejaculation (PE) is one of the foremost sex-related health problems among men. The global occurrence ranges from 20% to 30%, according to various studies. PE has a great impact on the men's quality of life, with deleterious effects such as embarrassment, frustration, and feeling of incompetence. Considering the necessity of treatment of PE, this study was planned to compare the efficacy and safety of OLNP-05 versus placebo for treating subjects suffering from PE. In this randomized clinical study, 60 men with PE were enrolled and randomly assigned to receive either OLNP-05 or placebo one capsule twice daily for a period of 8 weeks. Subjects were evaluated during visits on day 1, day 28, and day 56. Mean change from baseline in intravaginal ejaculatory latency time (IELT), improvement in premature ejaculation profile (PEP), and Clinical Global Impression-Improvement scale (CGI-I) were used to assess the efficacy of treatment. P-value <.05 was considered significant. At the end of the treatment, the improvement in IELT score in the OLNP-05 group was remarkably higher than the placebo. Subjects in the OLNP-05 treatment group also reported significantly greater improvement in PEP subscale score. Majority of OLNP-05-treated subjects were found to be in the "much improved" category as per CGI-I assessment. The result confirms the safety and efficacy of OLNP-05, therefore suggesting that OLNP-05 may be a safe and effective intervention for the management of PE. Trial registration: Clinical Trials Registry India (Registration No: CTRI/2017/08/009226, 02/08/2017).

Redox balance, metabolic fingerprint and physiological characterization in contrasting North East Indian rice for Aluminum stress tolerance.

Aluminum (Al) toxicity is a serious problem for rice crop productivity in acidic soils worldwide. The present work was conducted to look out for the alteration in ROS homeostasis; metabolic fingerprint; and morphology in two contrasting Indica rice cultivars of North East India (NE India) to Al toxicity. Al stress led to excess accumulation of ROS (H2O2 and O2-), and this in turn induced ROS mediated cellular damage, as indicated by lipid peroxidation both qualitatively as well as quantitatively. This excessive ROS production also led to significant reduction in chlorophyll content and stomatal conductance. This was followed by the loss of photosynthetic efficiency as detected by chlorophyll fluorescence. This excessive damage due to ROS prompted us to check the anti-oxidative machinery. Antioxidants, especially enzymes (SOD, APX, POX, GR, CAT, DHAR, MDHAR) are very important players in maintenance of ROS homeostasis. In tolerant variety Disang, higher activity of these enzymes and vice versa in sensitive variety, was observed in response to Al treatment. The non-enzymatic antioxidants (proline, ascorbate and glutathione) also showed similar trend. Though the tolerant variety showed strong anti-oxidative machinery, it was unable to completely nullify the stress experienced by the seedlings. Organic acids are also important players in detoxification of Al stress through efflux in the rhizosphere. In tolerant genotype, citrate exudate was found to be more when compared to sensitive genotypes on exposure to high dose of Al. This is supported by higher abundance of FRDL4, a citrate transporter. Not only FRDL4, other stakeholders for Al stress response like ART1 and ALS1 depicted prominent transcript abundance in the tolerant variety. In conclusion, through this study detailed physiological and metabolic characterisation of two contrasting Indica rice varieties Disang and Joymati, native to NE India for Al tolerance was performed for the very first time.

Genome-wide analysis of magnesium transporter genes in Solanum lycopersicum.

Magnesium (Mg) is an important micronutrient for various physiological processes in plants. In this study, putative Magnesium Transporter (MGT) genes have been identified in Solanum lycopersicum, Solanum tuberosum, Brachypodium distachyon, Fagaria vesca, Brassica juncea and were classified into 5 distinct groups based on their sequence homology. MGT genes are very diverse and possess very low sequence identity within its family. However, the Gly-Met-Asn (GMN) signature motif is present in most of the genes which are believed to be essential for Mg2+ recognition. In S. lycopersicum, different physiological root growth pattern was observed in both Mg excess and deficient conditions. Quantitative RT-PCR gene expression study shows that most of the SlMGT genes were upregulated in response to Mg deficient condition.