Deciphering the regulation of transporters and mitogen-activated protein kinase in arsenic and iron exposed rice.

This study investigates the influence of arsenic (As) and iron (Fe) on the molecular aspects of rice plants. The mRNA-abundance of As (OsLsi, OsPHT, OsNRAMP1, OsABCC1) and Fe (OsIRT, OsNRAMP1, OsYSL, OsFRDL1, OsVIT2, OsSAMS1, OsNAS, OsNAAT1, OsDMAS1, OsTOM1, OsFER) related genes has been observed in 12-d old As and Fe impacted rice varieties. Analyses of phytosiderophores synthesis and Fe-uptake genes affirm the existence of specialized Fe-uptake strategies in rice with varieties PB-1 and Varsha favouring strategy I and II, respectively. Expression of OsNAS3, OsVIT2, OsFER and OsABCC1 indicated PB-1's tolerance towards Fe and As. Analysis of mitogen-activated protein kinase cascade members (OsMKK3, OsMKK4, OsMKK6, OsMPK3, OsMPK4, OsMPK7, and OsMPK14) revealed their importance in the fine adjustment of As/Fe in the rice system. A conditional network map was generated based on the gene expression pattern that unfolded the differential dynamics of both rice varieties. The mating based split ubiquitin system determined the interaction of OsIRT1 with OsMPK3, and OsLsi1 with both OsMPK3 and OsMPK4. In-silico tools also confirmed the binding affinities of OsARM1 with OsLsi1, OsMPK3 and OsMPK4, and of OsIDEF1/OsIRO2 with OsIRT1 and OsMPK3, supporting our hypothesis that OsARM1, OsIDEF1, OsIRO2 were active in the connections discovered by mbSUS.

Iron reprogrammes the root system architecture by regulating OsWRKY71 in arsenic-stressed rice (Oryza sativa L.).

Iron (Fe) has been critically reported to act as a signal that can be interpreted to activate the molecular mechanisms involved in root developmental processes. Arsenic (As) is a well-known metalloid that restricts the growth and productivity of rice plants by altering their root architecture. Since root system architecture (RSA) under As stress targets WRKY transcription factors (TFs) and their interaction partners, the current investigation was carried out to better understand the Fe-dependent dynamics of RSA and its participation in this process. Here, we analyzed the effects of As and Fe (alone or in combination) exposed to hydroponically grown rice roots of 12-day-old plants. Our research showed that adding As to Fe changed how OsWRKY71 was expressed and improved the morphology and anatomy of the rice roots in Ratna and Lalat varieties. As + Fe treatment also manifested the biochemical parameters. OsWRKY71, revealed an up-regulation (Fe alone and As + Fe conditions) and down-regulation (As stress) in both varieties, in comparison to the controls. The improved root anatomy and root oxidizability indicated the enhanced capability of Lalat over the Ratna variety to induce OsWRKY71 for the better development of RSA during As + Fe treatment. Further, OsWRKY71 has revealed the presence of gibberellin-responsive cis-regulatory elements (GAREs) in its promoter region, indicating the involvement of OsWRKY71 in the gibberellin pathway. Molecular docking revealed that OsWRKY71 and SLR1 (DELLA protein) interact positively, which supports the hypothesis that Fe alters RSA by regulating OsWRKY71 through the gibberellin pathway in As-stressed rice.

Metabolomic profiling reveals key factors and associated pathways regulating the differential behavior of rice (Oryza sativa L.) genotypes exposed to geogenic arsenic.

Arsenic (As) toxicity is an escalating problem; however, information about the metabolic events controlling the varied pattern of As accumulation in rice genotypes within their natural environment is still lacking. The present study is thus an advancement in unravelling the response of such rice genotypes. Soil-water-rice samples were analyzed for As accumulation using ICP-MS. Furthermore, we implemented metabolomics through LC-MS/MS and UHPLC to identify metabolic signatures regulating As content by observing the metalloid's composition in rice agrosystem. Results showed that rice genotypes differed significantly in their levels of metabolites, with Mini mansoori and Pioneer having the highest levels. Mini mansoori contained least As which might have been regulated by Ala, Ser, Glu, Phe, Asn, His, Ile, Lys, Gln, Trp, Tyr, chlorogenic, p-coumaric, trans-ferulic, rutin, morin, naringenin, kampferol, and myricetin, while Asp, Arg, Met, syringic, epigalocatechin, and apigenin contributed to the greater As acclimatization ability of Pioneer. Multivariate tools separated the rice genotypes into two major clusters: Pioneer-Mini mansoori and Damini-Sampoorna-Chintu. KEGG identified three major metabolic pathways (aminoacyl-tRNA, phenylpropanoid, and secondary metabolites biosynthesis route) linked with As tolerance and adaptation mechanisms in rice. Overall, these two genotypes symbolize their As hostile and accommodating attitudes probably due to the accumulated metabolites and the physicochemical attributes of the soil-water. Thus, thorough understanding of the metabolic reactions to As may facilitate the emergence of As tolerant/resilient genotypes. This will aid in the selection of molecular markers to cultivate healthier rice genotypes in As-contaminated areas.

The heparin-binding hemagglutinin protein of Mycobacterium tuberculosis is a nucleoid-associated protein.

Nucleoid-associated proteins (NAPs) regulate multiple cellular processes such as gene expression, virulence, and dormancy throughout bacterial species. NAPs help in the survival and adaptation of Mycobacterium tuberculosis (Mtb) within the host. Fourteen NAPs have been identified in Escherichia coli; however, only seven NAPs are documented in Mtb. Given its complex lifestyle, it is reasonable to assume that Mtb would encode for more NAPs. Using bioinformatics tools and biochemical experiments, we have identified the heparin-binding hemagglutinin (HbhA) protein of Mtb as a novel sequence-independent DNA-binding protein which has previously been characterized as an adhesion molecule required for extrapulmonary dissemination. Deleting the carboxy-terminal domain of HbhA resulted in a complete loss of its DNA-binding activity. Atomic force microscopy showed HbhA-mediated architectural modulations in the DNA, which may play a regulatory role in transcription and genome organization. Our results showed that HbhA colocalizes with the nucleoid region of Mtb. Transcriptomics analyses of a hbhA KO strain revealed that it regulates the expression of ∼36% of total and ∼29% of essential genes. Deletion of hbhA resulted in the upregulation of ∼73% of all differentially expressed genes, belonging to multiple pathways suggesting it to be a global repressor. The results show that HbhA is a nonessential NAP regulating gene expression globally and acting as a plausible transcriptional repressor.

Unraveling the molecular aspects of iron-mediated OsWRKY76 signaling under arsenic stress in rice.

Arsenic (As) is a significant environmental element that restricts the growth and production of rice plants. Although the role of iron (Fe) to sequester As in rice is widely known, the molecular mechanism regarding As-Fe interaction remains opaque. Here, we show the differential response of two rice varieties (Ratna and Lalat) in terms of their morphological and biochemical changes in the presence of As and Fe. These results together with in-silico screening, gene expression analysis, and protein-protein interaction studies suggest the role of OsWRKY76 in Fe-mediated As stress alleviation. When OsWRKY76 is activated by MAPK signaling, it inhibits the gene expression of Fe transporters OsIRT1 and OsYSL2, which reduces the amount of Fe accumulated. However, MAPK signaling and OsWRKY76 remain down-regulated during Fe supplementation with As, which subsequently encourages the up-regulation of OsIRT1 and OsYSL2. This results in greater Fe content and decreased As accumulation and toxicity. The lower H2O2 and SOD, CAT, and APX activities were likewise seen under the As + Fe condition. Overall, results revealed the molecular aspects of Fe-mediated control of OsWRKY76 signaling and showed that Ratna is a more As tolerant variety than Lalat. Lalat, however, performs better in As stress due to the presence of Fe.

Iono-metabolomic guided elucidation of arsenic induced physiological and metabolic dynamics in wheat genotypes.

Despite the growing concerns about arsenic (As) toxicity, information on wheat adaptability in such an aggravating environment is limited. Thus, the present investigation based on an iono-metabolomic approach is aimed to decipher the response of wheat genotypes towards As toxicity. Wheat genotypes procured from natural conditions were characterized as high As-contaminated (Shri ram-303 and HD-2967) and low As-contaminated (Malviya-234 and DBW-17) based on ICP-MS As accumulation analysis. Reduced chlorophyll fluorescence attributes, grain yield and quality traits, and low grain nutrient status were accompanied by remarkable grain As accumulation in high As-contaminated genotypes, thus imposing a higher potential cancer risk and hazard quotient. Contrarily, in low As-contaminated genotypes, the richness of Zn, N, Fe, Mn, Na, K, Mg, and Ca could probably have supported less grain As accumulation, imparting better agronomic and grain quality traits. Additionally, from metabolomic analysis (LC-MS/MS and UHPLC), abundances of alanine, aspartate, glutamate, quercetin, isoliquiritigenin, trans-ferrulic, cinnamic, caffeic, and syringic bestow Malviya-234 as the best edible wheat genotype. Further, the multivariate statistical analysis (HCA, PCA, and PLS-DA) revealed certain other key metabolites (rutin, nobletin, myricetin, catechin, and naringenin) based genotypic discrimination that imparts strength to genotypes for better adaptation in harsh conditions. Out of the 5 metabolic pathways ascertained through topological analysis, the two main pathways vital for plant's metabolic adjustments in an As-induced environment were: 1. The alanine, aspartate and glutamate metabolism pathway, and 2. The flavonoid biosynthesis pathway. This is also evident from network analysis, which stipulates amino acid metabolism as a prominent As regulatory factor closely associated with flavonoids and phenolics. Therefore, the present findings are useful for wheat breeding programs to develop As adaptive genotypes that are beneficial for crop improvement and human health.

WRKY transcription factors: a promising way to deal with arsenic stress in rice.

Arsenic (As) is a global carcinogenic contaminant, and is one of the significant environmental constraints that limits the development and yield of crop plants. It is always tagged along with rice as rice takes up As and tends to accumulate it in grains. This amassment makes a way for As to get into the food chain that leads to unforeseen human health risks. Being viewed as parallel with toxicity, As in rice is an important global risk that calls for an urgent solution. WRKY Transcription Factors (TFs) seems to be promising in this area. The classical and substantial progress in the molecular mechanism of WRKY TFs, strengthened the understanding of innovative solutions for dealing with As in rice. Here, we review the potential of WRKY TFs under As stressed rice as a genetic solution and also provide insights into As and rice. Further, we develop an understanding of WRKY TF gene family and its regulation in rice. To date, studies on the role of WRKY TFs under As stressed rice are lacking. This area needs to be explored more so that this gene family can be utilized as an effective genetic tool that can break the As cycle to develop low or As free rice cultivar.

Micronutrient seed priming: new insights in ameliorating heavy metal stress.

Plants need to survive with changing environmental conditions, be it different accessibility to water or nutrients, or attack by insects or pathogens. Few of these changes, especially heavy metal stress, can become more stressful and needed strong countermeasures to ensure survival of plants. Priming, a pre-sowing hydration treatment, involves pre-exposure of plants to an eliciting component which enhance the plant's tolerance to later stress events. By considering the role of micronutrients in aiding plants to cope up under adverse conditions, this review addresses various aspects of micronutrient seed priming in attenuating heavy metal stress. Priming using micronutrients is an adaptive strategy that boosts the defensive capacity of the plant by accumulating several active or inactive signaling proteins, which hold considerable importance in signal amplification against the triggered stimulus. Priming induced 'defence memory' persists in both present generation and its progeny. Therefore, it is considered a promising approach by seed technologist for commercial seed lots to enhance the vigour in terms of seed germination potential, productivity and strengthening resistance response against metalloid stress. The present review provides an overview regarding the potency of priming with micronutrient to ameliorate harmful effects of heavy metal stress, possible mechanism how attenuation is accomplished, role of priming in enhancing crop productivity and inducing defence memory against the metalloid stress stimulus.

An insight into the act of iron to impede arsenic toxicity in paddy agro-system.

Surplus research on the widespread arsenic (As) revealed its disturbing role in obstructing the metabolic function of plants. Also, the predilection of As towards rice has been an interesting topic. Contrary to As, iron (Fe) is an essential micronutrient for all life forms. Past findings propound about the enhanced As-resistance in rice plants during Fe supplementation. Thus, considering the severity of As contamination and resulting exposure through rice crops, as well as the studied cross-talks between As and Fe, we found this topic of relevance. Keeping these in view, we bring this review discussing the presence of As-Fe in the paddy environment, the criticality of Fe plaque in As sequestration, and the effectiveness of various Fe forms to overcome As toxicity in rice. This type of interactive analysis for As and Fe is also crucial in the context of the involvement of Fe in cellular redox activities such as oxidative stress. Also, this piece of work highlights Fe biofortification approaches for better rice varieties with optimum intrinsic Fe and limited As. Though elaborated by others, we lastly present the acquisition and transport mechanisms of both As and Fe in rice tissues. Altogether we suggest that Fe supply and Fe plaque might be a prospective agronomical tool against As poisoning and for phytostabilization, respectively.

Root NRT, NiR, AMT, GS, GOGAT and GDH expression levels reveal NO and ABA mediated drought tolerance in Brassica juncea L.

Little is known about the interactive effects of exogenous nitric oxide (NO) and abscisic acid (ABA) on nitrogen (N) metabolism and related changes at molecular and biochemical levels under drought stress. The present study highlights the independent and combined effect of NO and ABA (grouped as "nitrate agonists") on expression profiles of representative key genes known to be involved in N-uptake and assimilation, together with proline metabolism, N-NO metabolism enzyme's activity and nutrient content in polyethylene glycol (PEG) treated roots of Indian mustard (B. juncea cv. Varuna). Here we report that PEG mediated drought stress negatively inhibited growth performance, as manifested by reduced biomass (fresh and dry weight) production. Total N content and other nitrogenous compounds (NO3-, NO2-) were decreased; however, NH4+, NH4+/ NO3- ratio and total free amino acids content were increased. These results were positively correlated with the PEG induced changes in expression of genes and enzymes involved in N-uptake and assimilation. Also, PEG supply lowered the content of macro- and micro-nutrients but proline level and the activity of ∆1-pyrroline-5-carboxylate synthetase increased indicating increased oxidative stress. However, all these responses were reversed upon the exogenous application of nitrate agonists (PEG + NO, PEG + NO + ABA, and PEG + ABA) where NO containing nitrate agonist treatment i.e. PEG + NO was significantly more effective than PEG + ABA in alleviating drought stress. Further, increases in activities of L-arginine dependent NOS-like enzyme and S-nitrosoglutathione reductase were observed under nitrate agonist treatments. This indicates that the balanced endogenous change in NO and ABA levels together during synthesis and degradation of NO mitigated the oxidative stress in Indian mustard seedlings. Overall, our results reveal that NO independently or together with ABA may contribute to improved crop growth and productivity under drought stress.

Bacillus anthracis chain length, a virulence determinant, is regulated by membrane localized serine/threonine protein kinase PrkC.

Anthrax is a zoonotic disease caused by Bacillus anthracis, a spore-forming pathogen that displays a chaining phenotype. It has been reported that the chaining phenotype acts as a virulence factor in B. anthracis In this study, we identify a serine/threonine protein kinase of B. anthracis, PrkC, the only kinase localized at the bacteria-host interface, as a determinant of B. anthracis chain length. In vitro, prkC disruption strain (BAS ΔprkC) grew as shorter chains throughout the bacterial growth cycle. A comparative analysis between the parent strain and BAS ΔprkC indicated that the levels of proteins, BslO and Sap, associated with the regulation of the bacterial chain length, were upregulated in BAS ΔprkC BslO is a septal murein hydrolase that catalyzes daughter cell separation and Sap is an S-layer structural protein required for the septal localization of BslO. PrkC disruption also has a significant effect on bacterial growth, cell wall thickness, and septa formation. Upregulation of ftsZ in BAS ΔprkC was also observed. Altogether, our results indicate that PrkC is required for maintaining optimum growth, cell wall homeostasis and most importantly - for the maintenance of the chaining phenotype.IMPORTANCEChaining phenotype acts as a virulence factor in Bacillus anthracis This is the first study that identifies a 'signal transduction protein' with an ability to regulate the chaining phenotype in Bacillus anthracis We show that the disruption of the lone surface-localized serine/threonine protein kinase, PrkC, leads to the shortening of the bacterial chains. We report upregulation of the de-chaining proteins in the PrkC disruption strain. Apart from this, we also report for the first time that PrkC disruption results in an attenuated cell growth, a decrease in the cell wall thickness and aberrant cell septa formation during the logarithmic phase of growth - a growth phase where PrkC is expressed maximally.

Improving clinical outcomes of very low birth weight infants: Implementation of standardized management guidelines in tertiary care hospital in Haryana.

BACKGROUND: Standardized written guidelines and protocols in NICU are known to impact neonatal outcomes and improve survival. OBJECTIVE: To study and compare the morbidity and mortality outcomes of very low birth weight (VLBW) neonates before and after introduction of structured approach to standardized management guidelines on four interventions in a tertiary care hospital in North India. METHODOLOGY: Structured approach to standardized management guidelines on four interventions were implemented for VLBW infants in NICU. a) Humidified and Heated High Flow Nasal Cannula (HHHFNC) as the initial mode of ventilator support in preterm VLBW babies. b) Expressed breast milk for feeding preterm VLBW babies and absolutely no formula milk. c) Hand washing and following "Bundle Care Approach" for Central lines as the cardinal cornerstones for maintaining strict asepsis. d) Development and supportive care to be regularly followed. Data was collected prospectively from July 2015 to December 2016 (Intervention Group) and compared with retrospective matched controls from the previous year (July 2014-June 2015) (Control Group). RESULTS: There was a significant decrease in culture positive sepsis in the intervention group compared to control group (3 (2.97%) CI:0.006-0.08 vs 11 (19.64%) CI:0.10-0.32; P = .0004). There was no significant difference in the mortality (5.35% vs3.96% P = .74) amongst the two groups. CONCLUSION: Implementing structured approach to above mentioned interventions in the form of standardized management guidelines for preterm VLBW neonates was associated with significant reduction in culture proven sepsis and mechanical ventilation days without affecting mortality or other co-morbidities.

Protective role of nitric oxide on nitrogen-thiol metabolism and amino acids profiling during arsenic exposure in Oryza sativa L.

Nitric oxide (NO) being a signaling molecule inside the plant cells, play significant role in signaling cascades and protection against environmental stresses. However, the protective role of NO in alleviating As toxicity in rice plants is currently not available. In the present study, the level of NO, nitrogen (N), inorganic N (nitrate, ammonium), thiols {TT (Total thiols), NPT (Nonprotein thiol)} and AAs contents along with N assimilating enzymes (NR, GDH, GOGAT) were analyzed after exposure of AsIII/NO treatment alone, and in combination. NO supplementation enhanced the content of N, inorganic N & thiol contents, NR, GOGAT activities, when compared with AsIII exposure alone. In AsIII exposed rice seedlings, content of AAs (except His, Arg, Met) reduced over the control, while supplementation of SNP improved AAs contents, compared to AsIII treatment alone. In conclusion, rice seedlings supplemented with NO tolerate the AsIII toxicity by reducing the N related parameters, thiol contents, altering the AA profile and enhanced the nutritional quality by increasing EAAs (essential amino acids) and NEAAs (non-essential amino acids).

Exposure of biosynthesized nanoscale ZnO to Brassica juncea crop plant: morphological, biochemical and molecular aspects.

The present work describes the in vitro synthesis and characterization of Zinc oxide nanoparticles (ZnO NPs) using an enzyme alpha amylase, the synthesized nanoparticles were used to study their beneficial effect in the growth and development of Brassica juncea. Transmission Electron Microscope (TEM) image reveals the average size of ZnO NPs was 11 nm and X-ray powder diffraction (XRD) suggests nanoparticles were crystalline in nature. In-silico study confirmed lysine, glutamine and tyrosine present in alpha amylase enzyme, plays a crucial role in the reduction of Zinc acetate dihydrate to ZnO NPs. The biochemical parameters and oxidative enzymes of Brassica juncea were compared with ZnO NPs treated plants. The effect of ZnO NPs on the cellular expression of metal tolerant protein (BjMTP) and cation efflux transporter gene (BjCET2) was also studied. The results indicate that nanoparticles can be used as a replacement for traditional harmful chemical fertilizers.

Photosynthetic activity and RAPD profile of polyethylene glycol treated B. juncea L. under nitric oxide and abscisic acid application.

The involvement of two extremely important signalling molecules, nitric oxide (NO) and abscisic acid (ABA) has been employed by plants to facilitate the adaptive/tolerate response during stressful conditions. However, the interactive role of exogenously applied NO and ABA is very less studied at physiological, biochemical and molecular levels. The present study therefore, evaluated the effects of individual and simultaneous addition of exogenous NO donor SNP (100µM) and ABA (10µM) on photosynthesis, Calvin-Benson cycle enzymes, S-assimilation enzymes, oxidative stress components, and genotoxicity in Brassica juncea cv. Varuna, exposed to polyethylene glycol (PEG)-induced drought stress. Results showed that a loss induced by PEG was significantly surpassed by the application of NO or/and ABA with PEG for chlorophyll content, net photosynthestic rate (Pn), internal CO2 concentration (Ci), stomatal conductance (gs), transpiration rate (Tr), maximum photosystem II (PSII) efficiency (Fv/Fm), actual PSII efficiency (ΦPSII), intrinsic PSII efficiency (Fv´/ Fm´), photochemical quenching (qP), non-photochemical quenching (NPQ), electron transport chain (ETC), ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCo), glyceraldehyde-3-phosphate dehydrogenase (GapDH), phosphoribulokinase (PRK), ATP-sulfurylase (ATP-S), and serine acetyltransferase (SAT) activities. The genomic template stability (GTS) (measured as changes in RAPD profiles) was significantly affected and showed varying degrees of DNA polymorphism, highest in PEG and lowest in PEG + NO and PEG + NO + ABA. Furthermore, the changes in RAPD profiles showed consistent results when compared with various photosynthetic and oxidative parameters. Altogether, this study concluded that supplementation of individual NO and together with ABA was more effective than individual ABA in alleviating PEG-induced drought stress in B. juncea L. seedlings.

Sulphur potentiates selenium to alleviate arsenic-induced stress by modulating oxidative stress, accumulation and thiol-ascorbate metabolism in Brassica juncea L.

The present study was designed to see the influence of selenium (Se) and sulphur (S) in the alleviation of arsenic (As)-induced stress in Brassica juncea plant. Se-induced alterations in physiological and biochemical responses due to deficient S (DS), normal S (NS) and additional S (AS) conditions were evaluated in 14-day-old seedlings of B. juncea variety Varuna. During the last 7 days of the 14-day-old seedlings, supplementation with arsenite (AsIII, 300 µM) alone and its combination with selenite (SeIV, 50 µM) along with different S treatments was done which are as follows: (i) control; (ii) As; (iii) As+Se+DS; (iv) As+Se + NS; (v) As+Se + AS. Experimental results showed that the application of AS in spite of NS supplied with Se influenced plant growth, oxidative stress and thiol-ascorbate-related parameters more prominently under As stress. The plants with As+Se+AS treatment exhibited lower ROS (superoxide and hydrogen peroxide ion), malondialdehyde (MDA) accumulation and lipoxygenase activity with increased activities of superoxide dismutase, catalase and ascorbate peroxidase compared with As+Se+NS condition. These plants also exhibited an increase in cysteine, non-protein thiols and phytochelatins, along with reduced, oxidised and redox content of glutathione and ascorbate. Furthermore, the application of S along with Se increased the activities of glutathione reductase, glutathione S-transferase, glutathione peroxidase, monodehydroascorbate and dehydroascorbate to minimise As stress. However, we observed that these responses were reversed under As+Se+DS condition and induced oxidative stress, which was almost similar to As only treatment. It indicated that AS nutrition potentiated Se to alleviate As-inhibited plant growth by modulating antioxidants including thiol-ascorbate-based mechanism and reducing As accumulation in B. juncea plants.

Facets of iron in arsenic exposed Oryza sativa varieties: A manifestation of plant's adjustment at morpho-biochemical and enzymatic levels☆.

Rice consumption is one of the primary sources of arsenic (As) exposure as the grains contain relatively higher concentration of inorganic As. Abundant studies on the ability of iron (Fe) plaque in hampering As uptake by plants has been reported earlier. However, little is known about its role in the mitigation of As mediated oxidative damage in rice plants. The present study highlights the effect of As and Fe co-supplementation on growth response, oxidative stress, Fe uptake related enzymes and nutrient status in rice varieties. Eight different Indica rice varieties were screened and finally four varieties (Varsha, Jaya, PB-1 and IR-64) were selected for detailed investigations. Improved germination and chlorophyll/protein levels during As+Fe co-exposure indicate healthier plants than As(III) treated ones. Interestingly Fe was found act both as an antagonist and also as a synergist of As treatments. It acted by reducing As translocation and improving the nutritional levels and enhancing the oxidative stress. Fe uptake related enzymes (nitrite reductase and ferric chelate reductase) and phytosiderophores analysis revealed that Fe supplementation can reduce its deficiency in rice plants. Morpho-biochemical, oxidative stress and nutrient analysis symbolizes higher tolerance of PB-1 towards As, while Varsha being most sensitive, efficiently combated the As(III) stress in the presence of Fe.

Nitric oxide and abscisic acid protects against PEG-induced drought stress differentially in Brassica genotypes by combining the role of stress modulators, markers and antioxidants.

The present study was designed to see the effect of exogenous nitric oxide (NO) and abscisic acid (ABA) and their interaction on physiological and biochemical activities in leaves and roots of two Indian mustard (Brassica juncea) cultivars [cv. Pusa Jagannath (PJN) and Varuna (VAR)] exposed to polyethylene glycol (PEG)-induced drought stress. Seven days old hydroponically grown seedlings were treated with PEG (10%), sodium nitroprusside, a NO donor [NO (100 µM)] and abscisic acid [ABA (10 µM)], using different combinations as: Control, ABA, NO, PEG, PEG + ABA, PEG + NO, and PEG + NO + ABA. Results revealed that in response to PEG-induced drought stress leaf relative water content, chlorophyll, carotenoid and protein content decreased with increased production of O2-●, MDA, H2O2, cysteine content and non-enzymatic antioxidants (including proline, flavonoid, phenolic, anthocyanin, and ascorbic acid), whereas, the enzymatic antioxidants (including SOD, CAT, APX, GR) showed the response range from no effect to increase or decrease in certain enzymes in both Brassica cultivars. The application of NO or/and ABA in PEG-stressed cultivars showed that both enzymatic and non-enzymatic antioxidants responded differently to attenuate oxidative stress in leaves and roots of both cultivars. Overall, PJN had the antioxidant protection mainly through the accumulation of non-enzymatic antioxidants, whereas VAR showed tolerance by the enhancement of both enzymatic and non-enzymatic antioxidant activities. Altogether, the study concluded that the independent NO and its interaction with ABA (PEG + NO and PEG + NO + ABA) were much effective than independent ABA (PEG + ABA) in lowering PEG-drought stress in Brassica cultivars.

Nitric oxide alters nitrogen metabolism and PIN gene expressions by playing protective role in arsenic challenged Brassica juncea L.

Plants have ability to adapt themselves through altering their growth process. In the present study, we examined exogenous application of nitric oxide (NO) on nitrogen metabolism and auxin (PIN) gene expression, and its possible role in alleviation of arsenic (As) toxicity in Brassica juncea seedlings. Seven days old hydroponically grown B. juncea seedlings were exposed to AsIII (150 µM), Sodium nitroprusside (NO donor, 100 µM), AsIII + SNP and control (without metal)for 48 h. Experimental results revealed that AsIII stress: enhanced the level of nitrite, NiR activity, NO3- and NH4+content as well as NADH-GOGAT activity; but GDH level decreased; enhanced content of amino acids; upregulated gene expression level of N metabolism and downregulated polar auxin transporter genes (PIN); inhibited plant growth and morphological parameters; increased MDA, H2O2, cysteine, proline content, enzymatic antioxidants (SOD, CAT, APX; GSH, TT, NPT); and decreased nutrient content. AsIII + SNP combination reduced the accumulation of As; improved growth; chlorophyll, protein and mineral nutrient content by scavenging ROS generation; maintained amino acids content; downregulated expression of N metabolism genes and upregulated expression of auxin transporter (PIN) genes . Additional biochemical data depicts reduction in the level of nitrogen related enzymatic activities, and other stress related parameters. Overall, this study provides an integrated view that exogenous SNP (NO donor) supplementation alleviated the inhibitory role of AsIII in B. juncea seedlings by altering nutrients, amino acids and auxin redistribution via expression of nitrogen and PIN gene profiling.

Waste water irrigation in the regulation of soil properties, growth determinants, and heavy metal accumulation in different Brassica species.

To evaluate the impact of waste water (WW) irrigation, four Brassica species, namely B. campestris, B. juncea, B. napus, and B. nigra, were grown for 2 years in the agricultural field. First-year experiment (2014-2015) was conducted with the comparative effect of WW and ground water (GW) under a uniform dose of NPK (N80P45K45, kg ha-1). WW irrigation proved efficacious over GW to increase growth, physiological, and yield parameters. Increase in all parameters was due to the use of WW which leads to the improvement in the physico-chemical properties of soil as compared to resulted soil from GW application. Second-year experiment (2015-2016) therefore deals with WW irrigation only but under interaction with two levels of NPK fertilizers (N80P45K45 and N60P30K30, kg ha-1). Results of this year revealed that maximum enhancement in growth, physiological, and yield parameters was observed at WW × N60P30K30 and the input of WW × N80P45K45 was not of benefit. WW × N60P30K30 treatment was beneficial also because, at this treatment level, the accumulation of Cr, Cu, Pb, Ni, and Cd in leaf and seed was comparatively lesser in amount than that of WW × N80P45K45. The study concluded even though the use of WW was applicable to save freshwater, enhance soil nutrient status, and make N, P, and K balance at their lower inputs, WW irrigation caused accumulation of heavy metals in all Brassica crops far above the safe limits during a quite longer irrigation time (70 days and 105 days after sowing (DAS)). However, WW was safe to use only up to 35 DAS. Therefore, the study suggested that there should be regular monitoring of heavy metal concentrations in irrigation water as well as in various crop vegetables.