Physiological and biochemical response of finger millet plants exposed to arsenic and nickel stress

Heavy metal stress is one of the major abiotic stresses that affects growth, development and yield in cereals. This investigation was conducted to examine the toxic effects of arsenic (As), nickel (Ni) and arsenic + nickel (As + Ni) on finger millet seedlings. The experiment involves exposing fourteen-day-old finger millet plants to various concentrations of As (10, 25, 50 and 100 µM), Ni (100, 250, 500 and 1000 µM) and As + Ni (10 + 100, 25 + 250, 50 + 500 and 100 + 1000 µM). The presence of heavy metals (HMs) led to oxidative stress and decreased root and shoot length, biomass, total chlorophyll, and leaf relative water content (LRWC). In addition, the levels of electrolyte leakage (EL), proline, H2O2, and MDA content increased significantly at higher concentrations of HMs (As >50 µM, Ni >500 µM and As + Ni >50 + 500 µM). An increased accumulation of As and Ni was found in roots compared to shoots. This is the first report to identify the physiological and biochemical responses of finger millet plants exposed to Arsenic and Arsenic + Nickel combined stress

Overexpression of Erianthus arundinaceus DREB2 Transcription Factor Ameliorates the Salinity and Drought Tolerance in Eleusine coracana Cultivars

Drought and salinity are the major constraints on agricultural production worldwide and a remarkable attempt is being made to improve the plant yields in the direction of increasing water deficit. We have developed transgenic finger millet cultivars ‘CO(Ra)-14’ and ‘Paiyur-2’ overexpressing Erianthus arundinaceous DREB2 (EaDREB2) transcription factor confirmed by PCR and Southern stably expressed in T0 and T1. These transgenic lines were tolerant to high salinity and severe drought stress conditions without affecting the morphological or agronomic characters. Analysis of morpho-physiological characters revealed that overexpression of EaDREB2 gene was associated with maintenance of chlorophyll content, increased relative water content, improved accumulation of the osmotic substance such as proline and decreased electrolyte leakage, under both saline and drought stresses. After treating the plants to progressive drought and salinity stress, transgenic lines showed less chlorophyll reduction and moderate growth inhibition than the controls. The majority of the transformed lines showed prominent tolerance to salinity and drought with significant spikelet fertility and higher grain yield compared to the controls at stressed and unstressed conditions. This is the first holistic report on development of drought and saline tolerance in finger millet through transgenic modification and it is essential to benefit the farmers from seasonal stress

Sprouted Sorghum Extract Elicits Coleoptile Emergence, Enhances Shoot and Root Acclimatization, and Maintains Genetic Fidelity in indica Rice

The high growth-stimulating effect of plant extract has urged the plant biotechnologists to use natural supplements in the culture media instead of synthetic phytohormones. We advocated the effect of sprouted sorghum extract (SSE) on emergence, in vitro acclimatization, and genetic fidelity in coleoptile derived callus of indica rice variety ADT36. The use of SSE with Murashige Skoog medium efficiently acclimatized the root and shoot apical systems. A higher mat and seminal roots (3.4 g biomass) with an efficient shoot primordium elongation were observed with an increase in the concentration of SSE. Seeds treated with SSE medium showed higher germination and earlier coleoptile maturation about 48 h compared to untreated seeds, and there was a higher expression of eEF-1α with an increase in coleoptile length. B5 medium was effective on inducing embryogenic and nodular callus from 3-day-old coleoptile with 3.0 mg/L 2,4-dichlorophenoxyacetic acid and further proliferated effectively with 0.8 mg/L kinetin with a fresh weight of 180 mg. Highly significant regeneration was observed with combination of 2.5 mg/L 6-benzylamino purine and 3.0 mg/L α-naphthaleneacetic acid. The metabolic and genetic profiles of in vitro and directly cultivated plants were the same, examined through Fourier-transform infrared spectroscopy, random amplified polymorphic DNA (RAPD), inter-simple sequence repeat (ISSR) and R-ISSR (combination of RAPD and ISSR) markers, respectively, and thus confirming the significant efficacy of the SSE incorporated medium. Disarmed T-DNA was transformed to coleoptile derived callus through Agrobacterium tumefaciens LBA4404 and confirmed by GUS assay. The T-DNA integration was confirmed by DNA blot analysis using DNA from transient GUS-expressed explants. Thus, SSE can be used as a natural and organic supplement for organogenesis and efficient acclimatizations of shoot and root apical meristems in regenerated plants

Effect of salinity stress on finger millet (Eleusine coracana (L.) Gaertn): Histochemical and morphological analysis of coleoptile and coleorhizae

The current study deals with the impact of salinity stress on growth and development of finger millet genotype ‘CO(Ra)-14’. The seeds were germinated on Murashige and Skoog solid medium supplemented with various concentrations of sodium chloride (NaCl) (0, 50, 100, 150 or 200 mM) for 15 days. Several physiological indices, including relative growth rate, electrolyte leakage, proline and chlorophyll (a, b and a + b) content, cell viability, hydrogen peroxide and caspase-like activity were measured to analyze the physiological and biochemical characteristics of saline stress. In addition, we also analyzed saline stress induced histochemical changes and level of lignin in the coleoptile and coleorhizae tissues. Relative growth of leaves and shoots of finger millet genotype ‘CO(Ra)-14’ exposed to 150 mM NaCl concentration was decreased while root length was increased. In addition, there was a significant increase in the levels of electrolyte leakage, contents of proline and hydrogen peroxide, and caspase-like activity from 0 to 200 mM NaCl. Chlorophyll and relative water contents were significantly reduced with decreased leaf succulence under increasing salinity. The microscopic observations of coleoptile and coleorhizae cross sections revealed considerable variations viz., length of epidermal cells, surface area and width of the cells with increasing salinity. Saline treated tissues were severely damaged and were intensely stained with phloroglucinol (suggesting the accumulation of cell bound phenolic compounds). Overall finger millet genotype ‘CO(Ra)-14’ showed a diverse response to salinity stress starting from seed germination to growth, and above 100 mM NaCl salinity is toxic to finger millet genotype ‘CO(Ra)-14’

AJWAIN SEEDS AS CAPPING AGENT FOR Bi2O3 NANOFLAKES: SYNTHESIS AND GROWTH INHIBITING EFFICIENCY OF BACTERIA

Objective: This work is mainly focused to determine the antibacterial activity of the green synthesized Bi2O3 nanoparticles against the bacterial strains, Staphylococcus aureus and Escherichia coli using resazurin as indicator. Methods: Bismuth oxide nanoparticles were synthesized from the precursor bismuth nitrate [Bi (NO3)3.5H20] by using trachyspermum ammi (ajwain) seed extract. To carry out these works, the synthesized Bi2O3 NPs undergone characterizations and were confirmed by UV-Vis, FT-IR, XRD, SEM and EDAX, TGA-DTA and DLS. Biological activity was done using a well diffusion method. Results: Bi2O3 NP's has been tested against bacteria (S. aureus and E. coli) in wells and shows blue colour, indicating bacterial growth inhibition in a dose-dependent manner for different concentrations. Conclusion: The biological studies were done with one gram-positive and one gram-negative bacteria to show the inhibiting efficiency. The synthesized bismuth oxide nanoparticles showed good anti-bacterial activity (different concentrations) against S. aureus and E. coli

Analysis of genetic variation in sorghum (Sorghum bicolor (L.) Moench) genotypes with various agronomical traits using SPAR methods

Genetic variation among 45 genotypes of sorghum (Sorghum bicolor L.) representing seven subpopulations was assessed using three single primer amplification reaction (SPAR) methods viz., inter-simple sequence repeat (ISSR), random amplified polymorphic DNA (RAPD) and directed amplification of minisatellite-region DNA (DAMD). Totally 15 ISSR, 8 RAPD and 7 DAMD primers generated 263 amplification products, accounting for 84.6% polymorphism across all the genotypes. The Mantel's test of correlation revealed the best correlation between ISSR and cumulative data with a correlation coefficient (r) of 0.84. Assessment of population diversity indicated that the maximum intra population genetic diversity was recorded among high FeZn lines (HFL) having maximum values of Nei's genetic diversity (h) (0.244), Shannon information index (I) (0.368) and the percentage of polymorphic loci (Pp) (72.65%) while the corresponding lowest values of 0.074, 0.109 and 17.95% respectively were observed among the members of MDT subpopulation. The mean coefficient of gene differentiation (GST) and the gene flow (Nm) between populations were observed to be 0.396 and 0.7680 respectively. The analysis of molecular variance (AMOVA) suggested that maximum genetic variation exists within populations (95%) than among populations (5%). Thus the information obtained from this study could be utilized in sorghum breeding programmes for the development of varieties with improved nutrition and agronomic values in future