Meenu Gupta

Characterisation of potential antigen(s) of Tilletia indica teliospore walls to develop a specific immunoassay for Karnal bunt detection

Abstract Characterisation of potential antigen(s) in the teliospore wall of Tilletia indica, the causal agent of Karnal bunt (KB) of wheat (Triticum aestivum) is necessary to generate specific immunoprobes for the development of reliable immunodiagnostic procedures. The intact teliospores of KB were used to generate anti-teliospore antibodies for the development of microtitre ELISA. The anti-teliospore antibodies cross-reacted with Tilletia foetida, Puccinia recondita and Puccinia striiformis suggesting that these species share one or more antigenic components. These antibodies recognised two unique immunoreactive bands of molecular weight ~34 kDa and ~15 kDa present in the spore wall fraction of T. indica after western blotting. The periodate treatment alone and sequential treatment of periodate followed by trypsin lost the immunoreactivity partially and completely, respectively. This suggests that cross-reactivity among bunt and rust of wheat fungal pathogens is most likely due to peptidal/oligosaccharide epitopes overlapping the spore walls glycoprotein.

Character association and path coefficient analysis for yield and quality traits in tomato (Solanum lycopersicum L.) under mid-hills of Himachal Pradesh

The present investigation was carried out to study the correlation and path coefficient between yield and quality traits at the experimental farm of Dr. Yaswant Singh Parmar University of Horticulture and Forestry, Solan during Kharif season, 2014. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications. Positive association of yield components with average fruit weight, plant height, inter-nodal distance, pericarp thickness and harvest duration was observed. Significant direct effect towards yield was contributed by average fruit weight followed by number of fruits per plant, pericarp thickness and harvest duration, whereas number of fruits per cluster, number of locules per fruit, days to first picking, total soluble solids and inter-nodal distance showed negative direct effect. The indirect effect of number of fruits per cluster was of sufficient magnitude via number of fruits per plant. Pericarp thickness and locular wall thickness also exhibited high indirect effect via average fruit weight. Considering the direct and indirect effect of various components characters, it was ascertained that average fruit weight, number of fruits per plant, pericarp thickness and harvest duration are the characters to be emphasized in improving the yield.

Outbreak of downy mildew of fenugreek in Solan district of Himachal Pradesh, India

Fenugreek (Trigonella foenum-graecum L.) is an annual crop with high medicinal value. Among different diseases, downy mildew (Peronospora trigonellae Gaum.) causes maximum crop loss. Since its first report of occurrence in Himachal Pradesh, it was considered a minor disease. But during the last 2-3 years, it has assumed serious proportion in Solan district of the state. The disease was found in all the fenugreek growing locations surveyed during 2011, 2012 and 2013 with maximum severity (37.33%) at Kandaghat. The morphological characters of the pathogen were also studied.

Morphological, Cultural, Pathological and Molecular Variability among Fusarium oxysporum f.sp. zingiberi isolates

Nineteen isolates of Fusarium oxysporum f.sp. zingiberi causal organism of Fusarium yellows in ginger were collected from different ginger growing areas of Himachal Pradesh and designated as I1 to I19. Morphological variations with respect to mycelial colour, conidial size and formation of chlamydospores and pathogenic variation in terms of disease incidence among different isolates was studied in these isolates. The mycelial colour varied from white to dull white with slightly pinkish tinge. The microconidial size varied from 5.20×4.00 μm (I8) to 12.30×5.70 μm (I3) whereas macroconidial size varied from 16.20×4.70 μm (I7) to 32.0×5.70 μm (I4). Chlamydospore dimensions also varied in all the nineteen isolates of the test pathogen. All isolates formed chlamydospores on PDA medium. Pathogenic variability revealed that lesion size varied from 8.50 to 18.00 mm after 10 days of inoculation whereas, incubation period varied from 11 to 19 days. Genetic variation was also analysed by using forty 10 – mer oligonucleotide RAPD primers, out of which 2 primers yielded informative, strong and reproducible DNA amplicons of Fusarium oxysporum f.sp. zingiberi and thus were selected for studying the variation among isolates. The dendrogram of DNA fingerprints revealed 0 to 80% variation among isolates. All isolates were grouped into two different major groups each comprising of ten and nine isolates, respectively.