Specific identification, biology and symptoms of whitefly species infesting sunflower in South India

Whitefly species related to sunflower was identified as Bemisia tabaci (Gennadius). Further the identified whitefly species was confirmed to be indigenous B. tabaci on molecular basis by using B-biotype specific SCARs and biological silver leaf assay on sensitive pumpkin (cv Big variety). None of the whitefly samples could positive for the presence of B biotype. The results of the study on the pest life cycle under the laboratory conditions showed that, B. tabaci passed through four nymphal instars before the adult stage. The mean duration values of these stages were 5.6, 4.2, 4.4 and 5.6 days respectively. The total duration of the life cycle of B. tabaci ranged from 23- 42 days at the temperature of 29±2°C with a mean of 34.5. The damage to sunflower crop caused by the whitefly species is discussed with a special emphasis on its ability to transmit leaf curl viral disease

Biological and molecular evidences on host range of leaf curl begomovirus disease of sunflower (Helianthus annuus L.)

The present study was conducted to identify the alternate hosts of new leaf curl virus disease of sunflower. In the present study several crops and weed hosts were cross inoculated with leaf curl virus of sunflower under laboratory through insect vector whitefly (Bemisia tabaci), further all inoculated samples were retested (3-4 weeks after inoculation) by molecular based Polymerse chain reaction diagnosis for the presence of virus. The results revealed that the causal virus of the disease was successfully transmitted from sunflower to sunflower (Helianthus annuus), tomato (Solanum lycopersicum) and tobacco (Nicotiana tabacum L) and weed hosts such as Acanthospermum hispidum, Amaranthus viridis and Parthenium hysterophorus in a short incubation period (2-3 weeks after inoculation), while on other hosts Chilli (Capsicum annuum L) and Datura stramonium, infection occurs in delayed incubation period. Further molecular analysis thorough polymerase chain reaction (PCR) diagnostic technique using virus specific primers also confirmed the presence of coat protein (CP) of leaf curl begomovirus invirus inoculated hosts viz., chilli, sunflower, tomato, and tobacco and weed hosts such as Acanthospermum hispidum, Amaranthus viridis, Datura stramonium and Parthenium hysterophorus. Thus, findings substantiate that the above hosts are major sources of the virus inoculum and served as potential alternate hosts of the disease during the off season

Global positioning system based spatial and temporal distribution of new leaf curl begomovirus disease on sunflower in Northern Karnataka

Leaf curl disease on sunflower caused by begomovirus genus of the family geminiviridae. Present investigations on field survey for disease incidence, field diagnostic symptoms and its spatial and temporal distribution in major sunflower growing parts of North Eastern Karnataka through GPS system during 2013-14, revealed that the disease was found to occur at all the stages of sunflower under field condition and exhibited symptoms such as vein thickening (enations) on abaxial surface of the leaves, upward curling and reduction in leaf size and severe discoluration of capitulum (Head) followed by bushy appearance. GPS based survey indicated that the % disease incidence varied from location to location (spatial variation) and also from season to season (temporal variation). The low incidence was noticed during Kharif condition which is ranged between 6.34-11.16, with the average incidence of 11.2%, 7.4% and 6.3% in Koppal, Raichur and Ballari districts repectively. Whereas during Rabi/summer season, high magnitude of disease noticed in many of the locations surveyed and is recorded upto 92.9 %. The GPS maps plotted based on PDI scale (0-3) represents high risk areas of the disease in Raichur and adjacent areas of Nort Eastern Karnataka and the result shows that the disease occurrence was more in rabi as compared to Kharif situations irrespective of locations. GPS survey map is an indicator to locate the nature of disease spread so as to conclude the hotspot areas

ANTIBACTERIAL ACTIVITY OF SYNTHESIZED SILVER NANOPARTICLES BY SIMAROUBAGLAUCA AGAINST PATHOGENIC BACTERIA

Objective: The present study outline the plant-mediated synthesis of silver nanoparticles (AgNPs) using leaf extract Simaroubaglauca, which act as both reducing and stabilizing agent.Methods: Formation of silver nanoparticles was confirmed by primarily by Ultraviolet/visible spectroscopy. X-ray diffraction studies revealed the crystallinity of the nanoparticles. The scanning electron microscopy was carried out to determine the mean particle size, as well as the morphology of the NPs and the composition of elements, was studied with Energy Dispersive X-ray analysis (EDS).Results: The silver nanoparticles were spherical in shape with a mean size of 23 nm. The EDS showed strong optical absorption peak at 3keV and it was confirmed the formation of AgNPs. The synthesised AgNPs further utilized for the evaluation of antibacterial activity and shown significant antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Enterobacter and Klebsiella pneumonia at 50 µg/ml and 100µg/ml concentrations.Conclusion: The synthesised silver nanoparticles have been characterised by UV-vis, SEM-EDAX and XRD to determine the sizes and shapes of the silver nanoparticles

Enhancement in production of recombinant two-chain Insulin Glargine by over-expression of Kex2 protease in Pichia pastoris

Glargine is an analog of Insulin currently being produced by recombinant DNA technology using two different hosts namely Escherichia coli and Pichia pastoris. Production from E. coli involves the steps of extraction of inclusion bodies by cell lysis, refolding, proteolytic cleavage and purification. In P. pastoris, a single-chain precursor with appropriate disulfide bonding is secreted to the medium. Downstream processing currently involves use of trypsin which converts the precursor into two-chain final product. The use of trypsin in the process generates additional impurities due to presence of Lys and Arg residues in the Glargine molecule. In this study, we describe an alternate approach involving overexpression of endogenous Kex2 proprotein convertase, taking advantage of dibasic amino acid sequence (ArgArg) at the end of B-chain of Glargine. KEX2 gene overexpression in Pichia was accomplished by using promoters of varying strengths to ensure production of greater levels of fully functional two-chain Glargine product, confirmed by HPLC and mass analysis. In conclusion, this new production process involving Kex2 protease over-expression improves the downstream process efficiency, reduces the levels of impurities generated and decreases the use of raw material

Ethnomedicinal plants and isolated compounds against Snake venom activity: A review

491-505Snakebite is an occupational hazard that has affected the population in tropical and subtropical countries. Worldwide approximately 5.4 million bites, 2.7 million envenomations, and 81,000-1,38,000 deaths are observed per annum. The incidences are higher among farmers and plantation workers. Antivenom is the only treatment available and the production of the same is challenging due to geographical variation of snakes, storage conditions, and non-availability of venom for production. Antivenom therapy is associated with immediate or delayed hypersensitivity and does not prevent local tissue damage. Thus the search for medicinal plants by the scientific community has become relevant. The ethnobotanical studies on various plants have revealed their use to treat various ailments including snakebite. Hence, the review is aimed to amass the medicinal plants studied and also emphasize various components isolated that have shown promising results

Breeding banana (Musa spp.) for drought tolerance: A review

Drought is a major abiotic stress affecting banana production worldwide, leading to yield losses of up to 65%. Consequently, numerous efforts to understand and mitigate drought effects that include developing tolerant crop varieties are ongoing in several banana breeding programmes. The breeding efforts, however, have been greatly slowed down by inherent banana problems (polyploidy and male or female sterility) and complexity of drought tolerance (reportedly controlled by several genes). This review summarizes the pertinent research findings on water requirements of banana for its proper growth and productivity, symptoms of drought‐sensitive varieties and field management strategies to cope with drought stress. The coping strategies deployed by resistant cultivars include high assimilation rates and water retention capacity as well as minor losses in leaf area and gaseous exchange. Reduced bunch weight, leaf chlorosis, wilting and strangled birth are underlined to be directly associated with drought susceptibility. Integration of conventional, molecular breeding and biotechnological tools as well as exploitation of the existing banana genetic diversity presents a huge opportunity for successful banana improvement