Plant Defense System Activated in Chili Plants by Using Extracts from Eucalyptus citriodora.

Capsicum annuum L. is infected by Fusarium Wilt and causes significant yield losses in Pakistan. Biological control is an excellent and environment friendly way. Presently, the biocontrol assays were conducted in pot trials using methanolic leaf extract of Eucalyptus citriodora L. where spray of extract prior to infection provided better protection from pathogen with maximum disease control. Further, Native page electrophoresis was performed to find out difference in expression profile of enzyme which revealed that control and T2 (Plant sprayed with Eucalyptus extract) did not exhibit any difference in their isozyme profile signifying no extra load of biological control measure on plant for the production of defense elements until the pathogen arrived. While in case of T3 （Protective treatment） and T4 (Curative treatment) extra isozyme (PO1) was observed in T4 only, PPO1 and PPO5, and PAL 2 and PAL 3 were comprised in higher quantities in T3 and T4 over control exposing the expression of plant metabolism under pathogen attack. The study concludes that the organic extract of E. citriodora have the potential to restrain the disastrous effects of pathogenic fungi. It will lead to the different aspect of biocontrol to suppress the plant pathogenic fungi in a broad spectrum.

Cytological and physiological basis for tomato varietal resistance against Alternaria alternata.

BACKGROUND: Since tomato is an important food component, it is imperative to enhance its yield against the activities of many devastating fungal pathogens such as Alternaria alternata. The exploitation of plant innate resistance by cultivation of resistant varieties is an effective measure in this regard. In the present study, 28 tomato varieties were tested against 32 A. alternata isolates, and representative varieties were further evaluated to determine the extent and basis of their antifungal resistance. RESULTS: A significant increase (104.7%) in polyphenols was recorded in the resistant variety Dinaar compared with the susceptible variety Red Tara. Dinaar also exhibited 100% enhancement of alkaloids and terpenoids along with a 30.7% increase in cell wall hemicellulose content. Significant differences were found in physical barriers (cellulose, lignin and pectin) of the representative varieties when stained tissue sections were subjected to colorimetric analysis. Similarly, polyphenol oxidase, peroxidase and phenylalanine ammonia lyase showed increases of 78.37, 114.67 and 125.11% respectively in the resistant variety. Higher expression of glucanase genes was evident from native gel analysis, in which not only the number of isozymes but also the quantity of individual isozymes was significantly increased. CONCLUSION: The resistant variety Dinaar had strong antifungal resistance and can therefore be recommended as suitable for cultivation in the agricultural system of Pakistan.

Management of Parthenium hysterophorus (Asteraceae) by Withania somnifera (Solanaceae).

This study was designed to evaluate the herbicidal activity of Withania somnifera (L.) Dunal against the noxious weed parthenium (Parthenium hysterophorus L.). In a laboratory bioassay, the effect of aqueous, methanol and n-hexane shoot and root extracts of 5%, 10%, 15% and 20% w/v concentrations (on a fresh weight basis) of W. somnifera were tested against the germination and seedling growth of parthenium. In general, aqueous and methanol extracts markedly suppressed the germination, root and shoot growth of parthenium. The shoot extracts were more inhibitory than the root extracts. In a foliar spray bioassay, the aqueous and methanol shoot extracts of 10% w/v (on a dry weight basis) concentration were sprayed on 1-week and 2-week-old pot-grown parthenium seedlings. Two subsequent sprays were carried out 5 and 10 days after the first spray. The aqueous and methanol extracts significantly reduced the length and biomass of parthenium shoots. In a soil amendment bioassay, the crushed shoots of W. somnifera were incorporated in the soil at 1-5% w/w. Parthenium seeds were sown one week after the residue incorporation and plants were harvested 40 days after sowing. All the soil amendment treatments significantly reduced seed germination by 43-89%. The highest dosages of 4% and 5% significantly suppressed the root and shoot biomasses of parthenium. This study concludes that foliar spray of aqueous and methanol extracts, and soil amendment with leaf residue of W. somnifera, can control the germination and growth of parthenium, one of the world's worst weeds.

Herbicidal effects of extracts and residue incorporation of Datura metel against parthenium weed.

The present study was designed to evaluate the herbicidal activity of Datura metel against the noxious weed parthenium (Parthenium hysterophorus L.). In a laboratory bioassay, the effect of aqueous, methanol and n-hexane shoot and root extracts of 5, 10, 15 and 20% w/v (on a fresh weight basis) concentration of D. metel were tested against the germination and seedling growth of parthenium. Both aqueous and methanol extracts markedly suppressed the germination and seedling growth of parthenium. Generally, the effect of shoot extracts was more pronounced than the effect of root extracts. In foliar spray bioassay, aqueous and methanol shoot extracts of 10% w/v (on dry weight bases) concentrations were sprayed on one-week and two-week-old pot-grown parthenium seedlings. Two subsequent sprays were carried out at five day intervals each. Both the aqueous as well as the methanol extracts significantly suppressed shoot length as well as shoot and root biomass of one-week and two-week-old parthenium plants. In residue incorporation bioassay, crushed shoots of D. metel were incorporated in the soil at 1, 2, ... 5% w/w. Parthenium seeds were sown one week after residue incorporation and plants were harvested 40 days after sowing. Incorporation of 2-5% residues significantly reduced germination by 47-89%. Residues of 4 and 5% concentration significantly suppressed plant biomass by 90 and 97%, respectively. The present study concludes that root and shoots of D. metel contain herbicidal constituents for the management of parthenium weed.

Herbicidal activity of Withania somnifera against Phalaris minor.

Herbicidal activity of Withania somnifera (L.) Dunal. was studied against Phalaris minor Retz., one of the most problematic weeds of wheat in Pakistan. In laboratory bioassays the aqueous, methanol and n-hexane extracts of 5, 10 and 15% w/v (fresh weight basis) of the roots and shoots of W. somnifera were applied. Extracts in the different solvents exhibited markedly variable herbicidal activities against germination and seedling growth of the target weed species. The methanol extracts showed the highest toxicity. Different concentrations of methanol shoot and root extracts declined the germination of P. minor by 21-71%, its shoot length by 40-72%, its root length by 50-99% and the plant biomass by 32-83%. The aqueous extracts proved to be comparatively less toxic than the methanol extracts, where generally the highest concentration of 15% exhibited pronounced toxicity against the target weed species. There was up to 48, 51, 99 and 55% suppression of the weed's germination, shoot length, root length and plant biomass, respectively, due to the 15% aqueous root and shoot extracts. Generally, the n-hexane extracts of both roots and shoots exhibited insignificant or stimulatory effects against weed shoot length and plant biomass. In a foliar spray bioassay, aqueous and methanol shoot extracts of 10% w/v (dry weight basis) concentration were sprayed on one- and two-week old pot grown P. minor seedlings. Two subsequent sprays were carried out at five day intervals each. The aqueous extract significantly reduced the shoot and root dry biomass of one-week old P. minor plants. In a residue incorporation bioassay, crushed shoots of W. somnifera were incorporated in the soil at 1, 2, ... 5% w/w. Phalaris minor seeds were sown one week after residue incorporation and plants were harvested 45 days after sowing. The lower concentrations of 2 and 3% significantly reduced, while higher concentrations of 4 and 5% of residue incorporation completely arrested, the germination of P. minor. The present study concludes that both roots and shoots of W. somnifera contain herbicidal constituents against P. minor.

Strain improvement and genetic characterization of indigenous Aspergillus flavus for amylolytic potential.

Aspergillus flavus FCBP-231, a filamentous fungus, was genetically modified for its ability to reveal extra cellular alpha-amylase activity. For strain improvement, the selected strains were subjected to UV irradiation (5-40 min exposure) and EMS treatment (50-300 microg mL(-1)) for hyper activity of an alpha-amylase enzyme. The mutants were quantitatively compared with the parental strain. UV and chemical mutagenesis brought about a dramatic enhancement in enzymatic activity. The mutant strains Af-UV-5.3 and Af-Ch-5.7 exhibited 79 and 110% more enzyme activity than the native strain A. flavus FCBP-231. This improvement in enzyme activity of the mutants suggests that they are suitable strains to be used in biotechnology. RAPD-PCR analysis revealed different patterns of amplicons of native as well as mutant derivatives, which suggested that the mutation imparted changes in the genetic make up of the mutants probably involved enzyme production control.

Mutagenesis and genotypic characterization of Aspergillus niger FCBP-02 for improvement in cellulolytic potential.

Cellulase is a collective term that encompasses enzymes which catalyze reactions that participate in the degradation of insoluble cellulose to soluble carbohydrates. In the present study, production of extra cellular cellulases by a filamentous fungus, Aspergillus niger FCBP-02, was studied in solid-state fermentation (SSF) as well as in submerged fermentation (SmF). Trials were conducted to evaluate the effect of mutagenesis by UV irradiation (5-40 min) and ethyl methane sulfonate (EMS) treatment (50-300 microg mL(-1)) to obtain hyper active cellulase enzyme producers among the potential strains. The enzyme activity assays of parental and mutant strains clearly revealed significantly higher cellulase activity of mutant A-Ch-5.5 (96 Units mL(-1)), followed by A-UV-5.6 (71 Units mL(-1)) with respect to the wild strain of A. niger FCBP-02 (53.7 Units mL(-1)). The profile of genetic variability among wild and mutant derivatives was scrutinized through RAPD-PCR. The expression pattern of mutants exhibited that the mutants were isogenic variants of the wild type and the out performance of the mutants could be attributed to the change in genetic make up.