Detection and identification of the blackeye cowpea mosaic strain of Bean common mosaic virus in seeds of cowpea from southern India

In different legume-growing regions of India, a total of 136 seed samples of cowpea (Vigna unguiculata (L.) Walp.) were collected and tested for the presence of the blackeye cowpea mosaic strain of Bean common mosaic virus, Cowpea aphid-borne mosaic virus, Cowpea mosaic virus, Cucumber mosaic virus and Bean yellow mosaic virus using growing-on test, enzyme linked immunosorbent assay, differential host test, electron microscopy and immuno-capture reverse transcription polymerase chain reaction. Among the 136 seedlots tested, 43 cowpea seedlots were found to be infected with BCMV-BlCM. The identity of three of these isolates as BCMV-BlCM was further supported by nucleotide sequencing in the 3' region of the genome. The incidence of seeds carrying transmissible virus ranged from 0.67% to 13.49%. In most cases, only symptomatic seedlings in a growing-on test were found infected with the virus

Antifungal Activity of <i>Eclipta alba</i> Metabolites against Sorghum Pathogens

Unscientific use of synthetic fungicides in plant disease management has environmental ramifications, such as disease resurgence and serious health problems due to their carcinogenicity. This has prompted the identification and development of eco-friendly greener alternatives. Eclipta alba extract was evaluated for its antifungal activity in in vitro and in vivo against sorghum fungal pathogens Fusarium thapsinum, Alternaria alternata, Epicoccum sorghinum, and Curvularia lunata. The column purified methanolic extract of E. alba exhibited good antifungal activity against the target pathogens. The MIC was observed at 80 mg/mL for all tested pathogenic fungi, whereas MFC was 80 mg/mL for E. sorghinum, 100 mg/mL for F. thapsinum, A. alternata, and C. lunata. In vitro germination percentage was significantly high in seeds treated with E. alba extract (98%) over untreated control (91%). Significant disease protection of 95% was observed in greenhouse and 66% disease protection was noticed in field experiments. The efficacy of E. alba extract in field conditions was improved with the use of E. alba extract formulation. The profile of phytochemicals in E. alba methanol fractions was obtained by ultra-performance liquid chromatography (UPLC) mass spectroscopy. The [M-H]&#8722; at m/z 313.3, m/z 797.9, and m/z 269.0 revealed the presence of wedelolactone, eclalbasaponin II, and apigenin, respectively. The H-nuclear magnetic resonance spectroscopy (1H-NMR) chemical shift value supported the findings of the mass spectrometry. The results highlighted the possible use of E. alba methanolic extract as alternative to chemical fungicide in sorghum disease management

Inhibition of virus infection by transient expression of short hairpin RNA targeting the methyltransferase domain of Tobacco mosaic virus replicase

One of the most efficient mechanisms by which plants protect themselves from viruses is the specific RNA-dependent silencing pathway termed post-transcriptional gene silencing (PTGS). Inhibition of Tobacco mosaicvirus in tobacco was demonstrated through transient expression of virus-derived short hairpin RNA encoding the methyltransferase domain of TMV replicase corresponding to the nucleotides 630 to 1,510 introduced through agro-infiltration into the leaves of tobacco plants. RT-PCR revealed that TMV infection was absent in hpRNA agro-infiltrated leaves while control leaves showed amplification of TMV. Protein analysis further confirmed the absence of TMV coat protein in hpRNA-containing leaves while it was prominent in the control leaves. Our data demonstrate that expression of hpRNA is an effective and predictable new approach to engineering resistance to TMV