Soil salinity is a major constraint to rice production in large inland and coastal areas around the world. Modern high yielding rice varieties are particularly sensitive to high salt stress. There ...are salt tolerant landraces and traditional varieties of rice but with limited information on genomic regions (QTLs) and genes responsible for their tolerance. Here we describe a method for rapid identification of QTLs for reproductive stage salt tolerance in rice using bulked segregant analysis (BSA) of bi-parental recombinant inbred lines (RIL). The number of RILs required for the creation of two bulks with extreme phenotypes was optimized to be thirty each. The parents and bulks were genotyped using a 50K SNP chip to identify genomic regions showing homogeneity for contrasting alleles of polymorphic SNPs in the two bulks. The method was applied to 'CSR11/MI48' RILs segregating for reproductive stage salt tolerance. Genotyping of the parents and RIL bulks, made on the basis of salt sensitivity index for grain yield, revealed 6,068 polymorphic SNPs and 21 QTL regions showing homogeneity of contrasting alleles in the two bulks. The method was validated further with 'CSR27/MI48' RILs used earlier for mapping salt tolerance QTLs using low-density SSR markers. BSA with 50K SNP chip revealed 5,021 polymorphic loci and 34 QTL regions. This not only confirmed the location of previously mapped QTLs but also identified several new QTLs, and provided a rapid way to scan the whole genome for mapping QTLs for complex agronomic traits in rice.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•MABB for incorporating Pi2 and Pi54 in the background of PB1121 and PB6 from two donors.•MABB for incorporating xa13 and Xa21 in the background of PB1121 and PB6 from P1460.•Phenotypic selection ...prior to background selection was indespensible in isolating novel recombinants.•SNPs provide better insights into RPG recovery than that of SSR markers.•Pyramids were resistant for bacterial blight and blast with high yield in multilocation evaluation.
Marker assisted backcross breeding was employed to incorporate the blast resistance genes, Pi2 and Pi54 and bacterial blight (BB) resistance genes xa13 and Xa21 into the genetic background of Pusa Basmati 1121 (PB1121) and Pusa Basmati 6. Foreground selection for target gene(s) was followed by arduous phenotypic and background selection which fast-tracked the recovery of recurrent parent genome (RPG) to an extent of 95.8% in one of the near-isogenic lines (NILs) namely, Pusa 1728-23-33-31-56, which also showed high degree of resemblance to recurrent parent, PB6 in phenotype. The phenotypic selection prior to background selection provided an additional opportunity for identifying the novel recombinants viz., Pusa 1884-9-12-14 and Pusa 1884-3-9-175, superior to parental lines in terms of early maturity, higher yield and improved quality parameters. There was no significant difference between the RPG recovery estimated based on SSR or SNP markers, however, the panel of SNPs markers was considered as the better choice for background selection as it provided better genome coverage and included SNPs in the genic regions. Multi-location evaluation of NILs depicted their stable and high mean performance in comparison to the respective recurrent parents. The Pi2+Pi54 carrying NILs were effective in combating a pan-India panel of Magnaporthe oryzae isolates with high level of field resistance in northern, eastern and southern parts of India. Alongside, the PB1121-NILs and PB6-NILs carrying BB resistance genes xa13+Xa21 were resistant against Xanthomonas oryzae pv. oryzae races of north-western, southern and eastern parts of the country. Three of NILs developed in this study, have been promoted to final stage of testing during the Kharif 2015 in the Indian National Basmati Trial.
KEY MESSAGE : A set of NILs carrying major blast resistance genes in a Basmati rice variety has been developed. Also, the efficacy of pyramids over monogenic NILs against rice blast pathogen ...Magnaporthe oryzae has been demonstrated. Productivity and quality of Basmati rice is severely affected by rice blast disease. Major genes and QTLs conferring resistance to blast have been reported only in non-Basmati rice germplasm. Here, we report incorporation of seven blast resistance genes from the donor lines DHMASQ164-2a (Pi54, Pi1, Pita), IRBLz5-CA (Pi2), IRBLb-B (Pib), IRBL5-M (Pi5) and IRBL9-W (Pi9) into the genetic background of an elite Basmati rice variety Pusa Basmati 1 (PB1). A total of 36 near-isogenic lines (NILs) comprising of 14 monogenic, 16 two-gene pyramids and six three-gene pyramids were developed through marker-assisted backcross breeding (MABB). Foreground, recombinant and background selection was used to identify the plants with target gene(s), minimize the linkage drag and increase the recurrent parent genome (RPG) recovery (93.5–98.6 %), respectively, in the NILs. Comparative analysis performed using 50,051 SNPs and 500 SSR markers revealed that the SNPs provided better insight into the RPG recovery. Most of the monogenic NILs showed comparable performance in yield and quality, concomitantly, Pusa1637-18-7-6-20 (Pi9), was significantly superior in yield and stable across four different environments as compared to recurrent parent (RP) PB1. Further, among the pyramids, Pusa1930-12-6 (Pi2+Pi5) showed significantly higher yield and Pusa1633-7-8-53-6-8 (Pi54+Pi1+Pita) was superior in cooking quality as compared to RP PB1. The NILs carrying gene Pi9 were found to be the most effective against the concoction of virulent races predominant in the hotspot locations for blast disease. Conversely, when analyzed under artificial inoculation, three-gene pyramids expressed enhanced resistance as compared to the two-gene and monogenic NILs.
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•New heterocyclic sulfonamide analogs synthesized as potential antibacterial agents.•The molecules docked with Bacillus anthracis dihydropteroate synthase enzyme (BaDHPS: PDB ...ID-3TYE).•Antibacterial activity determined using micro serial dilution method and cytotoxicity using MTT assay.•Fractional inhibitory concentration (FIC) determined using combination approach showed great synergistic effect.
A new series of heterocyclic molecules bearing sulfonamide linkage has been synthesized and screened for antibacterial activity. During antibacterial screening using broath dilution method, molecules were found to be highly active (MIC value 50–3.1 µg/mL) against different human pathogens, namely B. cerus, S. aureus, E. coli and P. aeruginosa, and most effective against E. coli. A great synergistic effect was observed during determination of FIC where molecules were used in combination with reference drugs chloramphenicol and sulfamethoxazole. The MIC value of the combination – varying concentration of test compounds and ½ MIC of reference drugs or varying concentration of reference drugs and ½ MIC of test compounds, was reduced up to 1/4 or 1/32 of the original value, indicating thereby the combination was 4–32 times more potent than the test molecule. The molecules also showed low degree of cytotoxicity against PBM, CEM and VERO cell lines. The results positively indicated towards the development of lead antibacterials using the combination approach.
Bacterial biofilm has been reported to be associated with more than 80% of bacterial infections. Curcumin, a hydrophobic polyphenol compound, has anti-quorum sensing activity apart from having ...antimicrobial action. However, its use is limited by its poor aqueous solubility and rapid degradation. In this study, we attempted to prepare quantum dots of the drug curcumin in order to achieve enhanced solubility and stability and investigated for its antimicrobial and antibiofilm activity. We utilized a newer two-step bottom up wet milling approach to prepare Curcumin Quantum Dots (CurQDs) using acetone as a primary solvent. Minimum inhibitory concentration against select Gram-positive and Gram-negative bacteria was performed. The antibiofilm assay was performed at first using 96-well tissue culture plate and subsequently validated by Confocal Laser Scanning Microscopy. Further, biofilm matrix protein was isolated using formaldehyde sludge and TCA/Acetone precipitation method. Protein extracted was incubated with varying concentration of CurQDs for 4 h and was subjected to SDS-PAGE. Molecular docking study was performed to observe interaction between curcumin and phenol soluble modulins as well as curli proteins. The biophysical evidences obtained from TEM, SEM, UV-VIS, fluorescence, Raman spectroscopy, and zeta potential analysis confirmed the formation of curcumin quantum dots with increased stability and solubility. The MICs of curcumin quantum dots, as observed against both select gram positive and negative bacterial isolates, was observed to be significantly lower than native curcumin particles. On TCP assay, Curcumin observed to be having antibiofilm as well as biofilm degrading activity. Results of SDS-PAGE and molecular docking have shown interaction between biofilm matrix proteins and curcumin. The results indicate that aqueous solubility and stability of Curcumin can be achieved by preparing its quantum dots. The study also demonstrates that by sizing down the particle size has not only enhanced its antimicrobial properties but it has also shown its antibiofilm activities. Further, study is needed to elucidate the exact nature of interaction between curcumin and biofilm matrix proteins.
The self-assembled three dimensional (3D) hybrids nanostructure containing uniform growth of vertical carbon nanotubes (VCNTs) with faceted iron oxide nanoparticles (f-Fe3O4 NPs) on the surfaces of ...reduced graphene oxide nanosheets (rGO NSs) is achieved using microwave assisted approach. The formation of hierarchical 3D f-Fe3O4-VCNTs@rGO hybrids, using microwave method is a rapid, simple, and inexpensive synthetic route. First, the VCNTs grow with help of Fe NPs, and after oxidizing of Fe NPs in form of f-Fe3O4 NPs, the growth has terminated resulting in formation of small size (<500 nm) VCNTs containing f-Fe3O4 NPs on its tip. The defect- and oxygen-rich sites of rGO NSs favor the heterogeneous nucleation and growth of f-Fe3O4 NPs on the tip of VCNTs. The synthesized 3D f-Fe3O4-VCNTs@rGO hybrid shows the improved electromagnetic interference (EMI) for microwave shielding effectiveness (SE) as compared to both rGO NSs and Fe3O4 NPs@rGO NSs materials. This 3D f-Fe3O4-VCNTs@rGO hybrid demonstrates the shielding effectiveness value more than ∼25 dB as compared to Fe3O4 NPs@rGO NSs for 1.0 mm thin film of 3D f-Fe3O4-VCNTs@rGO hybrids in microwave X-band (8.2–12.4 GHz). This applied microwave synthesis approach for 3D f-Fe3O4-VCNTs@rGO hybrids is simple, fast, reproducible and scalable for advanced EMI shielding materials. It can be concluded that the faceted Fe3O4 NPs on the tip of VCNTs which are grown in-situ on rGO NSs shows synergetic performance for EMI shielding elements in advanced application areas like spacecraft and aircraft.
Polypyrrole/carbon (PPy/C) composites have been synthesized using varying concentration of p-toluenesulfonate (pTS) dopant by surface initiated in-situ chemical oxidative polymerization with the ...purpose to develop an electrode material for supercapacitors. The influence of pTS on the structure of the composite is observed through Fourier transform infrared (FT-IR) and Raman spectroscopy while the morphological features have been examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The dc conductivity shows direct correlation with pTS concentration and follows Mott's three dimensional variable range hopping (3D-VRH) charge transport. The performance of PPy/C composite electrode for charge storage has been analyzed using electrochemical tools such as cyclic voltammetry and electrochemical impedance spectroscopy. The maximum specific capacitance similar to 395 F g super(-1) in 0.5 M Na sub(2)SO sub(4) aqueous solution with significant stability ( similar to 500 cycles) is obtained for the material synthesized using equimolar concentration (0.1 M) of pTS to pyrrole.
•Marker-assisted backcross improvement of mega varieties of rice.•QTLs for drought, submergence and salt tolerance.•Foreground and recombinant selection.•Background selection using high density 50K ...SNP chip.
Rice is a staple cereal of India cultivated in about 43.5Mha area but with relatively low average productivity. Abiotic factors like drought, flood and salinity affect rice production adversely in more than 50% of this area. Breeding rice varieties with inbuilt tolerance to these stresses offers an economically viable and sustainable option to improve rice productivity. Availability of high quality reference genome sequence of rice, knowledge of exact position of genes/QTLs governing tolerance to abiotic stresses and availability of DNA markers linked to these traits has opened up opportunities for breeders to transfer the favorable alleles into widely grown rice varieties through marker-assisted backcross breeding (MABB). A large multi-institutional project, “From QTL to variety: marker-assisted breeding of abiotic stress tolerant rice varieties with major QTLs for drought, submergence and salt tolerance” was initiated in 2010 with funding support from Department of Biotechnology, Government of India, in collaboration with International Rice Research Institute, Philippines. The main focus of this project is to improve rice productivity in the fragile ecosystems of eastern, northeastern and southern part of the country, which bear the brunt of one or the other abiotic stresses frequently. Seven consistent QTLs for grain yield under drought, namely, qDTY1.1, qDTY2.1, qDTY2.2, qDTY3.1, qDTY3.2, qDTY9.1 and qDTY12.1 are being transferred into submergence tolerant versions of three high yielding mega rice varieties, Swarna-Sub1, Samba Mahsuri-Sub1 and IR 64-Sub1. To address the problem of complete submergence due to flash floods in the major river basins, the Sub1 gene is being transferred into ten highly popular locally adapted rice varieties namely, ADT 39, ADT 46, Bahadur, HUR 105, MTU 1075, Pooja, Pratikshya, Rajendra Mahsuri, Ranjit, and Sarjoo 52. Further, to address the problem of soil salinity, Saltol, a major QTL for salt tolerance is being transferred into seven popular locally adapted rice varieties, namely, ADT 45, CR 1009, Gayatri, MTU 1010, PR 114, Pusa 44 and Sarjoo 52. Genotypic background selection is being done after BC2F2 stage using an in-house designed 50K SNP chip on a set of twenty lines for each combination, identified with phenotypic similarity in the field to the recipient parent. Near-isogenic lines with more than 90% similarity to the recipient parent are now in advanced generation field trials. These climate smart varieties are expected to improve rice productivity in the adverse ecologies and contribute to the farmer’s livelihood.
A hydrochemical study on a 630
km stretch of river Gomti, a tributary of the river Ganges examined the distribution of heavy metals in sediments and the partitioning of their chemical species between ...five geochemical phases (exchangeable fraction, carbonate fraction, Fe/Mn oxide fraction, and organic fraction) using Tessier's analytical sequential extraction technique. Most fractions in the sediments associated with the carbonate and the exchangeable fractions were between 11 and 30% except in a few cases where it was more than 50%. According to the Risk Assessment Code (RAC), the sediments having 11–30% carbonate and exchangeable fractions are at medium risk. The concentrations of cadmium and lead at mid Lucknow, Pipraghat, Sultanpur U/S and Sulthanpur D/S are between 31 and 50%. They thus pose a high risk to the environment. Since the concentrations of cadmium and lead at Neemsar (Cd 56.79%; Pb 51%) are higher than 50%, the RAC as very high. In most cases, the average metal concentrations were lower than the standard shale values. Various physicochemical parameters such as pH, total solids, total dissolved solids, total suspended solids, COD, BOD, DO, conductivity, chloride, sulphate, phosphate, fluoride, total alkalinity, total hardness, etc. were also reported.
The oxygen reduction reaction (ORR) is a core reaction for electrochemical energy technologies such as fuel cells and metal–air batteries. ORR catalysts have been limited to platinum, which meets the ...requirements of high activity and durability. Over the last few decades, a variety of materials have been tested as non‐Pt catalysts, from metal–organic complex molecules to metal‐free catalysts. In particular, nitrogen‐doped graphitic carbon materials, including N‐doped graphene and N‐doped carbon nanotubes, have been extensively studied. However, due to the lack of understanding of the reaction mechanism and conflicting knowledge of the catalytic active sites, carbon‐based catalysts are still under the development stage of achieving a performance similar to Pt‐based catalysts. In addition to the catalytic viewpoint, designing mass transport pathways is required for O2. Recently, the importance of pyridinic N for the creation of active sites for ORR and the requirement of hydrophobicity near the active sites have been reported. Based on the increased knowledge in controlling ORR performances, bottom‐up preparation of N‐doped carbon catalysts, using N‐containing conjugative molecules as the assemblies of the catalysts, is promising. Here, the recent understanding of the active sites and the mechanism of ORRs on N‐doped carbon catalysts are reviewed.
The development of metal‐free oxygen reduction reaction (ORR) catalysts based on N‐doped graphene, with high‐density active sites, is highly desirable. These catalysts, with acquired characteristics, are achievable through strategic design, via application of the combined knowledge of theoretical and experimental results. The homogeneously doped pyridinic N and the controlled catalyst surface hydrophobicity play a critical role in realizing high‐performance ORR catalysts.
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