An improved and efficient micropropagation of Eclipta alba through transverse thin cell layer culture and assessment of clonal fidelity using RAPD analysis

An improved and efficient in vitro regeneration system has been developed for Eclipta alba, a medicinally important plant, through transverse thin cell layer culture (tTCL). The transverse section of the nodal segment of field grown plants was used as tTCL explants for plant regeneration. Shoot multiplication from tTCL nodal explants was influenced by BAP and their interaction with Kin or NAA. MS medium containing 13.2 μM BAP and 4.6 μM Kin was most effective for shoot multiplication from tTCL nodal explants. Upon this medium, percent response for shoot proliferation was 100% with an average of 32.6 shoot buds per tTCL nodal explant. Regenerated shoots from tTCL nodal explants were rooted on the growth regulator free MS medium. The rooted plantlets were successfully acclimatized and established in soil with a survival frequency of 90-100%. Random amplified polymorphic DNA (RAPD) markers were used to evaluate the genetic fidelity of the micropropagated plants. RAPD profile analysis indicated that micropropagated plants were genetically similar to mother plant.     

Concomitant production of lipase, protease and enterocin by Enterococcus faecium NCIM5363 and Enterococcus durans NCIM5427 isolated from fish processing waste

Enterococci are widely distributed in the environment ranging from foods to humans and are gaining industrial importance due to their technological traits. In the present study, enterococci (Enterococcus faecium NCIM5363 (EF-63) and Enterococcus durans NCIM5427 (ED-27)) which are native to fish processing waste with an ability to produce lipase, protease and enterocin concomitantly were characterised. Lipase assay was performed by titrimetry and protease activity and was estimated using haemoglobin and casein as substrates in the presence of buffers at acidic, basic and neutral pH. Furthermore, enterocin produced by the isolates was characterised. Enterocin was also checked for its stability at different pH, temperature and proteolytic enzymes. Lipase production was found to be 22 and 10 U/ml in the absence of tributryin and increased to 40 and 24 U/ml in its presence for EF-63 and ED-27, respectively, indicating that the lipase produced is substrate dependent. Protease production was confirmed by protease assay, and the protease produced showed more affinity towards the acidic substrate. Enterocin produced was stable at low pH (2 to 3) and high temperature (121°C, 15 min) and had a molecular weight of approximately 6 kDa. It exhibited antibacterial activity against both Gram-positive and Gram-negative food-borne pathogens. Proteinase K inactivated enterocin completely, whereas trypsin did not. Novelty of this work lies in the immense industrial importance these cultures hold as they are capable of producing lipase, protease and enterocin apart from being useful in recovering proteins and lipids from fish processing wastes.     

Characterization of phosphate solubilizing fluorescent pseudomonads from the rhizosphere of Aloe vera (L.)

Soil phosphorous (P) deficiency is a major constraint to plant production which is overcome by adding inorganic-phosphate as chemical fertilizers. Fluorescent pseudomonads are the diverse group of bacteria able to mobilize sparingly soluble phosphate form. Total three hundred seven fluorescent Pseudomonas isolates were obtained from the Aloe barbadensis (Miller) rhizosphere. These Pseudomonas strains were further evaluated in vitro for their ability to solubilize phosphate and to produce indole acetic acid (IAA), hydrogen cyanide (HCN), siderophore and 1-aminocyclopropane 1- carboxylate (ACC) deaminase. Fifty three (36.8%) isolates produced IAA and 52 (36.1%) isolates produced siderophores whereas 36 (25.0%) and 31 (21.5%) isolates produced HCN and ACC deaminase, respectively. A positive correlation existed between siderophore and ACC deaminase producers. Cluster analysis showed rhizosphere as the major factor influencing the ecological distribution and physiological characterization of phosphate solubilizing bacteria (PSB). Based on partial 16S rRNA gene sequencing PSB were identified as Pseudomonas putida, Pseudomonas sp. and Pseudomonas plecoglossicida with highest phosphate solubilization ability. In conclusion, these phosphate solubilizing fluorescent pseudomonads would help in understanding their role in phosphorus solubilization and identification of potent phosphorus solubilizers from the rhizosphere of commercially grown A. barbadensis.     

Removal of Dyes Using Graphene-Based Composites: a Review

Water contamination has reached an alarming state due to industrialization and urbanization and has become a worldwide issue. Dyes contaminate water and are addressed extensively by researchers. Various technologies and materials have been developed for the treatment of contaminated water. Among them, adsorption has attracted great attention due to its ease and cost-effective nature. In recent years, graphene-based composites have shown great potential for the removal of contaminants from water. The literature reveals the usefulness of composites of graphene with metal oxides, carbon derivatives, metal hybrids and polymers for the removal of organic dyes from contaminated water. In this review, efforts have been made to compile the studies on the removal of cationic and anionic dyes from water using graphene-based composites.     

Dynamics of magnetic domain walls under their own inertia

The motion of magnetic domain walls induced by spin-polarized current has considerable potential for use in magnetic memory and logic devices. Key to the success of these devices is the precise positioning of individual domain walls along magnetic nanowires, using current pulses. We show that domain walls move surprisingly long distances of several micrometers and relax over several tens of nanoseconds, under their own inertia, when the current stimulus is removed. We also show that the net distance traveled by the domain wall is exactly proportional to the current pulse length because of the lag derived from its acceleration at the onset of the pulse. Thus, independent of its inertia, a domain wall can be accurately positioned using properly timed current pulses.     

Changes in enzyme activities,soluble sugars and phenols during in vitro adventitious shoot regeneration from leaflet explants of <Emphasis Type="Italic">Albizia procera</Emphasis> (Roxb.) Benth

Changes in nitrate reductase, i.e. NR (E.C. 1.7.1.1) activity, peroxidase (E.C. 1.11.1.14) activity, soluble sugars and phenols were monitored at various time intervals from day 0 to 60 during in vitro adventitious shoot regeneration from leaflet explants of Albizia procera (Roxb.) Benth. The explants were incubated on semi-solid Murashige and Skoog medium supplemented with 2.6 g l^?1 Phytagel^®, 2.5% sucrose, 10 μM BAP, 1 μM NAA and 15 μM AgNO₃. NR activity, soluble sugars and phenols exhibited initial sharp rise on around day 20 followed by steep decline on day 25, whereas peroxidase activity peaked on day 50, highlighting significance of early input of nitrogen and energy and late emergence of lignification process for cellular differentiation and organization into adventitious shoot primordia. Morpho-anatomical changes in leaflets at various stages of in vitro adventitious shoot formation also followed the endogenous biochemical pattern.     

Micropropagation of Darjeeling orange (Citrus reticulata Blanco) by shoot-tip grafting

Summary

Micropropagation of Darjeeling orange (Darjeeling mandarin) was done by shoot-tip grafting on the local rootstocks rough lemon, sour orange and Rangpur lime. Seedlings of these plants were raised in MS medium in standard conditions of temperature, light duration and plant age. Microbuds (0.2 mm long), aseptically excised from the scion, were grafted onto the decapitated rootstock seedlings. The micrografts in culture medium were grown under standard lighting. Rootstock seedlings showed optimum growth at 25–30°C. Optimum growth of the micrografts resulted from treatment in complete darkness for 4 d after grafting followed by exposure to 750 W for 16 h d^?1 for 15 d and 1500–2000 W for 16 h d^?1 for 39 d. The success of micrografting depended on the age of the rootstock seedling which was 21 d, 14 d and 14 d for sour orange, rough lemon and Rangpur lime respectively. The micrografts were then double grafted to the two year old rootstocks seedlings of the respective species and the age of the micrografts for the successful double grafts was also standardized. The survival rate was high with 40 d, 45 d and 45 d micrografts on sour orange, rough lemon and Rangpur lime respectively. The double-grafts were then indexed for tristeza virus and greening disease after six months’ growth in an insect-proof screenhouse and found to be free from these graft transmissible diseases.     

Influence of increasing doses of nitrogen and organic matter on nitrogen loss from sodium nitrate

There is a general belief that most of the nitrogen contained in artificial nitrogenous fertilizers is utilized by the growing crops when applied to them. But unfortunately the Position is not so and the recovery of nitrogen from artificial fertilizers remains only in the neighbourhood of 50%. Indeed, the loss of nitrogen from artificial fertilizers is often even more than 50% as indicated by the following observations of RUSSELL (1) : “Crops that respond to nitrogen manuring commonly take up and fix in their tissues between one-third and one-half of the nitrogen added as sulphate of ammonia and a rather high proportion of nitrogen added as nitrate, the remainder is lost .... though its fate has not been too well determined.”     

Genetic diversity among pearl millet maintainers using microsatellite markers

Genetic diversity among 70 maintainers and two pollinators of sub-Saharan and Indian origin was studied for simple sequence repeat (SSR) loci using 34 primer pairs. A total of 213 alleles were detected with an average of 6.26 alleles per locus. Polymorphic information content (PIC) ranged from 0.05 to 0.96 with a mean of 0.58 for the SSR loci. Mean PIC across the linkage groups and number of alleles in dinucleotide motifs varied significantly. The lowest PIC (0.239) for linkage group 6 indicated comparatively conserved nature of this linkage group. Genetic similarity estimates ranged from 0.05 to 0.73 with an average value of 0.29. This indicated sufficient diversity among the maintainer and pollinator lines. The 72 lines fell in five clusters, and the clustering pattern corroborated with their pedigree and characteristic traits. Pollinator ICMR 356 was more diverse from the maintainer lines analysed, and can be a potential parent for pearl millet hybrid development.     

Molecular genetic mapping of quantitative trait loci associated with loaf volume in hexaploid wheat (Triticum aestivum)

Major efforts in wheat research are being made to improve the yield and quality of wheat. Loaf volume (Lv) is the main quality parameter deciding the bread making potential of wheat. To genetically dissect quantitative trait loci (QTLs) for Lv, a Recombinant Inbred Line (RIL) population (F₈) was developed from a cross between two Indian wheat varieties “HI 977” and “HD 2329”. A total of 914 SSR and 100 ISSR primers were used for molecular analysis and the genetic map comprising 19 chromosomes was constructed with 202 SSR markers and 2 HMW glutenin subunit loci: Glu-B1 and Glu-D1. The phenotypic data were collected from six environments including three different agro-climatic zones for 2 consecutive years. Dissection of Lv through AMMI model revealed significant G×E variance for the trait. QTL analysis was performed using composite interval mapping. A total of 30 QTLs for Lv were detected and significant QTLs were identified on 6B and 6D chromosomes; 1B, 1D, 2A, 3A, 5B and 5D also contributed genetically to Lv. Association between 6B and 6D QTLs and variable expression of gliadins on group 6 chromosomes were discussed. QTLs detected in this study were compared with other QTL analysis in wheat.