Biofabrication of zinc oxide nanoparticles from Melia azedarach and its potential in controlling soybean seed-borne phytopathogenic fungi.

Present study, report the biofabrication of zinc oxide nanoparticles from aqueous leaf extract of Melia azedarach (MaZnO-NPs) through solution combustion method and their novel application in preventing the growth of seed-borne fungal pathogens of soybean (Cladosporium cladosporioides and Fusarium oxysporum). The standard blotter method was employed to isolate fungi and was identified through molecular techniques. The characterization of MaZnO-NPs was carried out by UV-Vis spectroscopy, Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) equipped with Energy Dispersive Spectroscopy (EDS) and Transmission Electron Microscopy (TEM). The physicochemical characterization confirmed the particles were of high purity and nano size (30-40 nm) with a hexagonal shape. The synthesized MaZnO-NPs inhibited the growth of C. cladosporioides and F. oxysporum in a dose dependent manner. Biomass, ergosterol, lipid peroxidation, intracellular reactive oxygen species and membrane integrity determination upon MaZnO-NPs treatment offered significant activities there by confirming the mechanism of action against the test pathogens. In conclusion, due to the effectiveness of MaZnO-NPs in controlling the growth of C. cladosporioides and F. oxysporum, the synthesized MaZnO-NPs provides insight towards their potential application in agriculture and food industries.

Fusarium oxysporum f. sp. lycopersici causal agent of vascular wilt disease of tomato: Biology to diversity- A review.

Tomato (Lycopersicon esculentum) is one of the widely grown vegetables worldwide. Fusarium oxysporum f. sp. lycopersici (FOL) is the significant contributory pathogen of tomato vascular wilt. The initial symptoms of the disease appear in the lower leaves gradually, trail by wilting of the plants. It has been reported that FOL penetrates the tomato plant, colonizing and leaving the vascular tissue dark brown, and this discoloration extends to the apex, leading to the plants wilting, collapsing and dying. Therefore, it has been widely accepted that wilting caused by this fungus is the result of a combination of various physiological activities, including the accumulation of fungal mycelia in and around xylem, mycotoxin production, inactivation of host defense, and the production of tyloses; however, wilting symptoms are variable. Therefore, the selection of molecular markers may be a more effective means of screening tomato races. Several studies on the detection of FOL have been carried out and have suggested the potency of the technique for diagnosing FOL. This review focuses on biology and variability of FOL, understanding and presenting a holistic picture of the vascular wilt disease of tomato in relation to disease model, biology, virulence. We conclude that genomic and proteomic approachesare greater tools for identification of informative candidates involved in pathogenicity, which can be considered as one of the approaches in managing the disease.

Specific PCR-based detection of Phomopsis vexans the cause of leaf blight and fruit rot pathogen of Solanum melongena L.

Leaf blight and fruit rot disease caused by Phomopsis vexans is a devastating disease of brinjal. The detection of P. vexans in plant parts and seeds of brinjal can be complicated, mainly when the inoculum is present at low levels and/or overgrown by fast-growing saprophytic fungi or other seed-borne fungi. A PCR-based diagnostic method was developed with specific primers designed based on sequence data of a region consisting of the 5·8S RNA gene and internal transcribed spacers, ITS 1 and ITS 2 of nuclear ribosomal RNA gene (rDNA) repeats of P. vexans. The efficiency and specificity of primer pairs PvexF/PvexR designed were established by PCR analysis of DNA from P. vexans strains isolated from India and fungal isolates of other genera. A single amplification product of 323-bp was detected from DNA of P. vexans isolates. No cross-reaction was observed with any of the other isolates tested. The specific primers designed and employed in PCR detected P. vexans up to 10 pg from DNA isolated from pure culture. This is the first report on the development of species-specific PCR assay for identification and detection of P. vexans. Thus, PCR-based assay developed is very specific, rapid, confirmatory and sensitive tool for the detection of pathogen P. vexans at early stages. SIGNIFICANCE AND IMPACT OF THE STUDY: Phomopsis vexans is an important seed-borne pathogenic fungus responsible for leaf blight and fruit rot in brinjal. Current detection methods, based on culture and morphological identification is time consuming, laborious and are not always reliable. A PCR-based diagnostic method was developed with species-specific primers designed based on sequence data of a region consisting of the 5·8S RNA gene and internal transcribed spacers, ITS 1 and ITS 2 of nuclear ribosomal RNA gene (rDNA) repeats of P. vexans.

Antibacterial and antimitotic potential of bio-fabricated zinc oxide nanoparticles of Cochlospermum religiosum (L.).

Zinc oxide nanoparticles synthesized through eco-friendly approach has gained importance among researchers due to its broad applications. In the present work, hexagonal wurtzite shape nanoparticles (below 100 nm size) were obtained using aqueous leaf extract of Cochlospermum religiosum which was confirmed through X-Ray diffraction (XRD) analysis. The synthesized ZnO-NPs showed an absorption peak at 305 nm which is one of the characteristic features of ZnO-NPs.The bio-fabricated ZnO-NPs were of high purity with an average size of ∼76 nm analyzed through Dynamic Light Scattering (DLS) analysis supporting the findings of XRD. The SEM images confirmed the same with agglomeration of smaller nanoparticles. The composition of aqueous leaf extract and ZnO-NPs was explored with Fourier Transform Infrared Spectroscopy (FT-IR). The plant extract as well as bio-fabricated ZnO-NPs offered significant inhibition against Gram-positive (B. subtilis and Staph. aureus) and Gram-negative (P. aeruginosa and E. coli) bacteria. The minimum inhibitory concentration (MIC) of bio-fabricated ZnO-NPs and plant extract was found between 4.8 and 625 µg/ml against test pathogens, which was authenticated with live and dead cell analysis. Apart from antibacterial potentiality, antimitotic activity was also observed with a mitotic index of 75.42% (ID50 0.40 µg mL-1) and 61.41% (ID50 0.58 µg mL-1) in ZnO-NPs and plant extract, respectively. The results affirm that plant extract and its mediated ZnO-NPs possess biological properties.

Cytotoxic and pro-apoptotic effects of Abrus precatorius L. on human metastatic breast cancer cell line, MDA-MB-231.

Abrus precatorius is highly regarded as a universal panacea in the herbal medicine with diverse pharmacological activity spectra. This experimental study on the mechanism of the anticancer activity of A. precatorius leaf extracts, may offer new evidence for A. precatorius in the treatment of breast cancer in clinical practice. Cell death was determined by using MTT assay. Further analyses were carried out by doing DNA laddering, PARP cleavage, FACS, semi-quantitative RT-PCR and detection of cellular reactive oxygen species (ROS) by DCFDA assay. A. precatorius showed very striking inhibition on MDA-MB-231 cells. MTT assay showed more than 75 % inhibition of the cells and treated cells indicated visible laddering pattern with thick compact band. PARP cleavage produced 89 kDa cleavage product which was associated with apoptosis. Flow cytometer exhibited a sub-G0/G1 peak as an indicative of apoptosis. mRNA expression level of apoptosis-related genes p21 and p53 was markedly increased in cells treated with the extract as compared to control. The up-regulation of p21 and p53 may be the molecular mechanisms by which A. precatorius extract which induces apoptosis. An increase in the concentration of A. precatorius extract does not generate ROS, instead it reduces ROS formation in MDA-MB-231 cells, as evident from the shift in fluorescence below untreated control. This is the first report showing that A. precatorius leaf extract exhibits a growth inhibitory effect by induction of apoptosis in MDA-MB-231 cells. Our results contribute towards validation of the A. precatorius extract as a potentially effective chemopreventive or therapeutic agent against breast cancer.