Evaluation of lawsonia inermis leaf extracts for their in vitro fungitoxicity against certain soilborne pathogens

Screening of Lawsonia inermis leaf extracts for their fungitoxicity was carried out in vitro against some selected soil-borne phytopathogens, Rhizoctonia solani. Pythium aphanidermatum and Macrophomina phaseolina. Of the three solvent extracts studied, cold-water extract at 10% concentration showed a maximum of 70% inhibition of the mycelial growth of R. solani. Methanol extract at 2.5% concentration completely inhibited P. aphanidermatum while the same at 10% proved effective against M. phaseolina by 60% when compared to cold water and petroleum ether extracts. Petroleum ether extract was ineffective against R. solani and M. phaseolina. The amount of total phenols was 4.5 mg/g of fresh leaf tissue. Reverse phase high performance liquid chromatographic analysis of the cold-water extracts revealed the presence of four different absorption peaks of which only two compounds could be identified i.e. tannic acid and catecho

Direct somatic embryogenesis and organogenesis pathway of plant regeneration can seldom occur simultaneously within the same explant of sorghum

Sorghum (Sorghum bicolor) is an important staple food crop, especially of the poor in Africa, Asia and Central America and needs to be improved through genetic engineering. Generation of transgenic plants depends mainly on the standardization of an efficient tissue culture and regeneration protocol. Sorghum tissue culture and regeneration protocols mostly follow either organogenesis (Maheswari et al. 2006) or direct somatic embryogenesis pathway (Harshavardhan et al. 2002). Following the protocol of Girijashankar et al. (2005), we attempted to produce transgenic sorghum with synthetic Bt gene constructs (ubicry1Ab and ubicry1Ac, separately). However, molecular analysis of the T0 and their progeny plants revealed the loss of germline transmission of the respective transgenes under study. Recent studies by Wang et al. (2005) with Agrobacterium-mediated transformation of maize (Zea mays) and regeneration through embryogenic callus, reported the absence of transgenes in the progeny plants. We report here the occurrence of different types of calli, few of which are not expected to occur during the direct somatic embryogenesis pathway of sorghum regeneration protocol followed to obtain the above transgenic plants

Development of transgenic sorghum for insect resistance against the spotted stem borer (Chilo partellus)

Transgenic sorghum plants expressing a synthetic cry1Ac gene from Bacillus thuringiensis (Bt) under the control of a wound-inducible promoter from the maize protease inhibitor gene (mpiC1) were produced via particle bombardment of shoot apices. Plants were regenerated from the transformed shoot apices via direct somatic embryogenesis with an intermittent three-step selection strategy using the herbicide Basta. Molecular characterisation based on polymerase chain reaction and Southern blot analysis revealed multiple insertions of the cry1Ac gene in five plants from three independent transformation events. Inheritance and expression of the Bt gene was confirmed in T1 plants. Enzyme-linked immunosorbant assay indicated that Cry1Ac protein accumulated at levels of 1–8 ng per gram of fresh tissue in leaves that were mechanically wounded. Transgenic sorghum plants were evaluated for resistance against the spotted stem borer (Chilo partellus Swinhoe) in insect bioassays, which indicated partial resistance to damage by the neonate larvae of the spotted stem borer. Reduction in leaf damage 5 days after infestation was up to 60%; larval mortality was 40%, with the surviving larvae showing a 36% reduction in weight over those fed on control plants. Despite the low levels of expression of Bt delta-endotoxin under the control of the wound-inducible promoter, the transgenic plants showed partial tolerance against first instar larvae of the spotted stem borer

Dynamic simulation of a boiling water nuclear reactor

For the application of modern control theory, specifically optimal control, to the boiling water reactor, it is necessary to have a linear model that is validated. In this paper the nonlinear model of the BWR derived on the basis of physical laws and empirical relations is linearized around an operating point and the model is verified against experimental results by simulating various tests such as the pressure transient test, change in power to recirculating pump etc. The transport delay occurring in the model is approximated by various representations and the results are compared with the exact delay representation. Validation such as discussed in the paper forms the basis for devising appropriate control strategies in the presence of disturbances