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Introduction: Banded sheath blight (Bsb) disease, caused by Rhizoctonia solani , is an emerging problem in barnyard millet cultivation. One of the significant goals of pathogenomic research is to identify genes responsible for pathogenicity in the fungus. Methods: A virulence profiling-based approach was employed and six R. solani isolates were collected from various ecological zones of India. The morphological parameters and virulence of all of the six R. solani isolates were investigated. The most virulent strain was designated as RAP2 and its genome has been sequenced, assembled, and annotated. Results: The RAP2 genome is 43.63 megabases in size and comprises 10.95% repetitive DNA, within which 46% are retroelements, 8% are DNA transposons, and 46% are unidentified DNA. The Gene Ontology (GO) annotation of RAP2 proteins revealed that "phosphorylation", "membrane", and "ATP binding" have the highest gene enrichment in the "biological process", "cellular component" and "molecular function" domains, respectively. The genome comprises a majority of secretory proteins in the pectin lyase fold/virulence factor superfamily, which break down plant cell wall polymers to extract saccharides. The RAP2 genome is comparable to R. solani , which infects maize and rice, but it diverges further from soybean in terms of nucleotide-level genetic similarity. Orthologous clustering of RAP2 protein sequences with R. solani infecting maize, rice, and soybean yields 5606 proteins shared across all genomes. GO analysis of 25 proteins specific to the RAP2 genome found enrichment in the ethylene response, which can cause spore germination and infection in host plants. Discussion: Interestingly, a 28-bp deletion in the RAP2 strain's cutinase domain was discovered in the cutinase protein, which might be important in the infection process, perhaps rendering the enzyme inactive or allowing the pathogen to infect barnyard millet while avoiding host defense. This study sheds light on the genetic makeup of R. solani , allowing researchers to discover critical genes related with pathogenicity as well as potential targets for fungicide development. [ABSTRACT FROM AUTHOR]

This article reports the first occurrence of Pyrenophora avenicola causing leaf spot on oat plants in India. The disease was observed in Ludhiana, Punjab, and further surveillance revealed its presence in 52 out of 60 fields in the state. The symptoms included brownish-black lesions on the leaves, which gradually enlarged and formed blight. The fungus was isolated and identified through morphological and molecular techniques, confirming P. avenicola as the causal organism. Pathogenicity was also confirmed through inoculation experiments. This finding is significant as oat is an economically important crop, and neglecting this disease may lead to damage. [Extracted from the article]

Blast disease causes significant damage to millets (pearl millet, finger millet and foxtail millet) and rice in India. This study investigates strains of Pyricularia, the causal agent of blast disease, in rice and millets in India in terms of their diversity, host preferences and phylogeny. One hundred and thirty‐six Pyricularia isolates causing rice and millet blast were collected from 46 locations in India. They displayed morphological diversity irrespective of host or location. All Pyricularia isolates were separated into two major clusters by a multilocus sequence‐based phylogenetic tree, which also demonstrated that most isolates are grouped according to their host associations. In contrast, a few finger millet isolates were found to be grouped with foxtail millet isolates. We explored how Pyricularia isolates behaved when exposed to rice and millets. Finger millet isolates were shown to be pathogenic on a wide variety of millets, whereas rice isolates were only found to infect rice and wheat. The majority of the blast isolates of millets were shown to be pathogenic on common weed species of the millet ecosystem, such as Echinochloa crusgalli, Eleusina indica and Erogrotis gagantica. Our findings emphasize the importance of pathogen surveillance in both cultivated crops and weed hosts, as well as the possible risk of blast fungus infection in Indian millets due to host expansion. Blast disease control programmes in India will be greatly enhanced by the knowledge gained in this study on the diversity and host association of Pyricularia strains. [ABSTRACT FROM AUTHOR]

Direct monitoring of the formation and growth of nanoparticles by microscopy in real time is of fundamental interest in understanding the chemical and self assembly processes involved. Such studies are difficult to implement in solution, but have been carried out on solid substrates, mostly under specialized conditions, including ultra high vacuum. The present study illustrates the facility with which in situgrowth of metal nanoparticles in thin polymer films under ambient conditions can be monitored by real time atomic force microscopy. Formation of silver nanoparticles inside spin-coated thin films of poly(vinylpyrrolidone) containing silver nitrate, under ambient conditions, is revealed by the emergence and growth of surface plasmon resonance absorption extending over several hours. Atomic force microscopy allows ‘direct observation’ of structures growing near the surface; individual nanostructures can be monitored in the case of very thin films. A plausible mechanism is proposed for the chemical reactions occurring inside the film with the polymer itself acting as the reducing agent leading to the formation and growth of the nanoparticles. The present study opens up new avenues to carry out investigations into the mechanisms and kinetics of nanoparticle growth. [ABSTRACT FROM AUTHOR]

Detection of mercury at concentration levels down to parts-per-billion is a problem of fundamental and practical interest due to the high toxicity of the metal and its role in environmental pollution. The extensive research in this area has been focused primarily on specific sensing of mercuric (Hg(2+)) ion. As mercury exists in the oxidation states, +2, +1 and 0 all of which are highly toxic, a universal sensor covering all the three while ensuring high sensitivity, selectivity, and linearity of response, and facilitating in situ as well as ex situ deployment, would be very valuable. Silver nanoparticle-embedded poly(vinyl alcohol) (Ag-PVA) thin film fabricated through a facile protocol is shown to be a fast, efficient and selective sensor for Hg(2+), Hg(2)(2+) and Hg in aqueous medium with a detection limit of 1 ppb. The sensor response is linear in the 10 ppb to 1 ppm concentration regime. A unique characteristic of the thin film based sensor is the blue shift occurring concomitantly with the decrease in the surface plasmon resonance absorption upon interaction with mercury, making the sensing highly selective. Unlike the majority of known sensors that work only in situ, the thin film sensor can be used ex situ as well. Examination of the thin film using microscopy and spectroscopy through the sensing process provides detailed insight into the sensing event., (© 2011 American Chemical Society)