Phoma is the most widely distributed and omnipresent genus of the order Pleosporales and the largest genus with some 3,000 taxa described so far. Of these, approximately 110 species are pathogenic and occupy varied ecological niches. The genus Phoma is polyphyletic and is not really delimited, with unclear species boundaries that make it a taxonomically controversial genus. Fungi belonging to Phoma commonly occur on crop plants that are economically important, where they cause devastating plant diseases. Pathogenic members of Phoma sensu lato species attack crop plants with symptoms ranging from leaf blight to root rot, and even wilting of the plant. In infected crop residues and field stubbles, the pathogen produces abundant pycnidia and pseudothecia that serve as the source of primary inoculum, whilst repeated crops of conidia produced inside pycnidia are the main source of secondary infection during the same growing season. After successful infection, the pathogen produces various phytotoxins that alter photosynthetic efficiency and actin cytoskeleton‐based functions, and cause electrolyte leakage from cells. Controlling the diseases caused by members of Phoma sensu lato is challenging and efforts have been made to identify resistant varieties that can be used in various plant breeding programmes. Studies have also been conducted to devise cultural and biological control measures as well as to evaluate the efficacy of fungicides against members of Phoma sensu lato. In this review we aim to discuss the disease epidemiology and control measures that can be practised to protect crops from Phoma diseases.
Background: Herbal extracts of Andrographis paniculata (AP) and Hedyotis corymbosa (HC) are known as hepato-protective and fever-reducing drugs since ancient time and they have been used regularly by the people in the south Asian sub-continent. Methanolic extracts of these two plants were tested in vitro on choloroquine sensitive and resistant (MRC-pf-303) strains of Plasmodium falciparum for their anti-malarial activity.
Viviparous1 (Vp1) encodes a B3 domain-containing transcription factor that is a key regulator of seed maturation in maize (Zea mays). However, the mechanisms of Vp1 regulation are not well understood. To examine physiological factors that may regulate Vp1 expression, transcript levels were monitored in maturing embryos placed in culture under different conditions. Expression of Vp1 decreased after culture in hormone-free medium, but was induced by salinity or osmotic stress. Application of exogenous abscisic acid (ABA) also induced transcript levels within 1 h in a dose-dependent manner. The Vp1 promoter fused to b-glucuronidase or green fluorescent protein reproduced the endogenous Vp1 expression patterns in transgenic maize plants and also revealed previously unknown expression domains of Vp1. The Vp1 promoter is active in the embryo and aleurone cells of developing seeds and, upon drought stress, was also found in phloem cells of vegetative tissues, including cobs, leaves, and stems. Sequence analysis of the Vp1 promoter identified a potential ABA-responsive complex, consisting of an ACGT-containing ABA response element (ABRE) and a coupling element 1-like motif. Electrophoretic mobility shift assay confirmed that the ABRE and putative coupling element 1 components specifically bound proteins in embryo nuclear protein extracts. Treatment of embryos in hormone-free Murashige and Skoog medium blocked the ABRE-protein interaction, whereas exogenous ABA or mannitol treatment restored this interaction. Our data support a model for a VP1-dependent positive feedback mechanism regulating Vp1 expression during seed maturation.
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