Thidiazuron-induced morphogenesis of Regal geranium (Pelargonium domesticum): A potential stress response

Thidiazuron (TDZ), a phenylurea derivative with cytokinin-like activity, induced the development of outgrowths on root tissue of vegetatively propagated geraniums (Pelargonium × hortorum, Pelargonium domesticum and Pelargonium graveolens). Root outgrowths developed as globular or elongated structures following treatment with 10–30 μM TDZ and many of these structures differentiated to produce shoots. Analysis of root and shoot samples, collected daily during the outgrowth induction phase and at the end of the treatment period, revealed significant changes in accumulation of manganese, iron, copper, calcium, magnesium and potassium. The markers of a stress response, proline, abscisic acid and 4-aminobutyrate, accumulated in the TDZ-treated roots during the first week of induction. Assessment of the adenylate phosphate pool sizes of the TDZ-treated plants indicated a sequential increase in the endogenous levels of ATP, ADP and AMP following each application of TDZ. The energy charge ratio was also significantly higher in TDZ-treated plants indicating an increase in ATP utilizing systems. Similarily, pyridine nucleotide pool size analyses revealed that TDZ-treated plants had a higher level of endogenous NADP⁺ in the initial 24-h period following each treatment and the level of NADPH increased following the third application of TDZ. The ratio of NADPH/NADP⁺ was significantly higher in TDZ-treated plants throughout the treatment period. We hypothesize that the primary effect of TDZ was through induction of a stress response in the geranium plants. In order to overcome this stress, the plants accumulated significantly higher levels of proline, ABA and 4-aminobutyrate. Moreover, the plants also exhibited modified metabolic processes which in turn led to increased availability of energy and reducing power required for subsequent growth and to initiate stress adaptation mechanisms including modified cellular processes and regenerative outgrowth development.     

NUTRIENT SEQUESTRATION,BIOMASS PRODUCTION BY MICROALGAE AND PHYTOREMEDIATION OF SEWAGE WATER

The present work was aimed at analysing the role of inoculated microalgae in nutrient dynamics, bioremediation and biomass production of sewage water. Preliminary microscopic analyses of sewage water revealed the presence of different algal groups, with predominance of Cyanophyta. Among the inoculated strains, Calothrix showed highest dry cell weight (916.67 mg L^?1), chlorophyll and carotenoid content in tap water + sewage water (1:1) treatment. Significant removal of NO₃-N ranging from 57–78% and PO₄-P (44–91%) was recorded in microalgae inoculated tap water + sewage water. The total dissolved solids and electrical conductivity of tap water + sewage water after incubation with Calothrix sp. decreased by 28.5 and 28.0%, accompanied by an increase in dissolved oxygen from 4.4 to 6.4 mg L^?1 on the 20th day. Our investigation revealed the robustness of Calothrix sp. in sequestering nutrients (N and P), improving water quality and proliferating in sewage water.     

Alterations in the structure of phycobilisomes of the cyanobacterium,Spirulina platensis in response to enhanced Na+ level

Incubation of Spirulina platensis at enhanced Na⁺ concentrations resulted in 30% increased intracellular accumulation of Na⁺ ions. This accumulation of Na⁺ ions intracellularly altered the phycobilisome organization as revealed by transmission electron microscopic data and changes in the absorption spectrum. The room temperature emission peak at 638 nm in the control sample was blue-shifted by 7 nm in the treated samples suggesting phycobilisome disorganization. SDS-PAGE of phycobilisome polypeptides showed a significant increase in a 66.2 kDa polypeptide. This is the first report that the enhanced concentration of intracellular Na⁺ ion alters the structure of the phycobilisome in S. platensis. This revised version was published online in November 2006 with corrections to the Cover Date.     

An ecological study of the macrophytic vegetation of the Doodhadhari Lake,Raipur, M. P., India

Summary Physical factors operating in Doodhadhari Lake were studied periodically during 1967–68. Thermal stratification in the lake was found to be induced by solar radiation during daytime and destroyed by nocturnal cooling and mixing of the lake waters as evidenced by temperature records. Light intensities at different strata were found to be reduced by plant growth. At 0.5 m depth and 1 m depth considerable reduction in light intensities was found. The floating-leaved rooted plants and free-floating sudd communities curtailed the light transmission to 0.0 – 0.1% at 0.5 m depth. Visibility also decreases considerably owing to shading by the plants at different stations.A part of the thesis submitted for the Degree of Doctor of Philosophy.     

Genetic analysis of Pongamia pinnata (L.) Pierre populations using AFLP markers

A study of genetic diversity in Pongamia pinnata representing 33 candidate plus trees (CPT) was undertaken in five agro-ecological zones of Southern Peninsular India. Eleven primer combinations generated 532 bands with an average of 48 bands per primer combination. E-ACG/M-GCC showed the highest polymorphism of 98.80 %. E-ACG/M-GCC, E-CAA/M-CTG, and E-CAG/M-GTG with higher polymorphic information, marker index, and resolving power were found to be effective in detecting unique bands. Nei's gene diversity and Shannon's indices of 0.159 and 0.247, respectively, indicated the presence of high gene diversity in southern dry and transition zones of Karnataka. The inter-population differentiation between zones (G _ST) was 0.296. The level of gene flow (Nm) estimated was 1.34. Analysis of molecular variance indicated that 44.78 % of variance occurred within the provenance when compared to variations among agro-ecological zones (22.22 %) and among provenances within zones (33 %). Based on un-weighted pair group method using arithmetic averages method, the pongamia accessions were grouped into three major clusters and four sub-groups depending on their geographical locations. The diverse CPT identified in this study could be selected and used for tree breeding, germplasm conservation, and biofuel program in India and other tropical countries.     

Quantitative estimation of newly synthesized radioactive proteins: use of minicolumns of antibody embedded in agarose gel or immobilized on Sepharose.

Immunochemical methods for the quantitative determination of radioactive proteins synthesized by chick embryo hepatocyte cultures are described. Cell culture medium containing secreted labeled serum proteins was concentrated and applied to agarose gels containing rabbit anti-chicken serum. Nonspecific binding in control gels was reduced to less than 2% of applied counts under conditions where more than 60% of the nondialyzable counts were precipitated in the presence of antibody. Labeled cytosol fructose-1,6-bisphosphatase (Fru-P₂ase) from cell sonicates was selectively adsorbed onto columns containing Sepharose-immobilized anti-chicken liver Fru-P₂ase. Radioactivity bound on these columns was eluted with 1% sodium dodecyl sulfate for electrophoretic analysis. Addition of dialyzed horse serum was used in both cases to minimize nonspecific binding. These techniques provide simple alternatives to direct immunoprecipitations in solution where nonspecific binding of radioactivity may be unacceptably high.     

Exploring Crop–Microbiome Interactions Towards Improving Symbiotic Performance of Chickpea (Cicer arietinum) Cultivars Using Cyanobacterial Inoculants

The significance of integrated nutrient management practices is well established in improving the productivity of chickpea (Cicer arietinum); however, the effects of the inoculation of cyanobacterial inoculants on nodule metabolism, microbiome and associated genes are less explored. In the present investigation, cyanobacterium Anabaena laxa (A. laxa) and biofilm developed using Anabaena torulosa, with Mesorhizobium ciceri as a partner (An-M. ciceri), were evaluated along with Mesorhizobium ciceri (M. ciceri) alone, in three chickpea cultivars. Microbial inoculation led to 40–70% enhancement in nitrogen fixation, leghaemoglobin and ureide content, and two- to threefold increment in nitrate reductase and phosphoenolpyruvate carboxylase activity of the nodules. An enhancement of 30–50% in the soil available macro- and micronutrients and plant growth attributes was also observed. A significant correlation between the soil microbiological and plant parameters was recorded, particularly in relation to the nitrogen dynamics. Increases in the leghaemoglobin content in nodules due to An-M. ciceri, A. laxa and M. ciceri ranged from 18 to 40%, particularly in chickpea cv. BG372 in which 60–80% enhancement was recorded. Whereas the nifH gene copies in the nodule tissues ranged from 5.00 × 10⁶ to 3.35 × 10⁷ g⁻¹, the application of A. laxa led to higher abundances of nifH gene copies in desi chickpea cv. BG372 and kabuli BG1053 cultivars. An-M. ciceri, followed closely by A. laxa, was the top-ranking treatment, and chickpea cv. BG372 was the best performing cultivar; An-M. ciceri—chickpea cv. BG372 proved to be the superior combination for higher plant growth and soil nutrient-related traits.