Somasekhar N
DRR, Crop Protection, Faculty Member
We studied variation in isozyme patterns of 8 metabolic enzymes in 5 species of Heterorhabditis (H. bacteriophora, H. indica, H. marelata, H. megidis, and H. zealandica) comprising 18 isolates. Isozyme banding patterns of all the 8... more
We studied variation in isozyme patterns of 8 metabolic enzymes in 5 species of Heterorhabditis (H. bacteriophora, H. indica, H. marelata, H. megidis, and H. zealandica) comprising 18 isolates. Isozyme banding patterns of all the 8 enzymes were species specific; however, 3 enzymes, i.e., arginine kinase, fumarate hydratase, and malate dehydrogenase, displayed distinct patterns among all the 18 isolates. Phylogenetic analysis of the isozyme patterns produced dendrograms depicting a high degree of genetic variation among Heterorhabditis species, with the average pairwise distance of 0.2000. Trees constructed using different phylogenetic methods showed a relatively close genetic relationship between H. megidis and H. zealandica and between H. bacteriophora and H. indica. Also, H. bacteriophora HP88 was the most distant species from H. megidis (UK isolate), H. marelatus (Oregon isolate), and H. zealandica (X1 isolate) with pairwise distance of 0.1957, 0.2228, and 0.2120, respectively. Phylogenetic analysis also revealed genetic variation among H. bacteriophora isolates with the average pairwise distance of 0.1507. GPS2 and GPS3 were the most closely related isolates with the average distance of only 0.0870, followed by GPS1 and GPS2 with average distance of 0.1087. In contrast, KMD19 and HP88, OH25, and HP88, and OH25 and Acows isolates were the most divergent populations with a pairwise distance of 0.2011 and 37 character differences. Pairwise distance analysis also revealed that genetic divergence among populations of H. bacteriophora is relatively independent of geographic distance. Overall, these results demonstrate strong subspecies structuring in H. bacteriophora.
Research Interests:
Research Interests:
Infectivity of twenty nine entomopathogenic nematode (EPN) isolates belonging to the families of Heterorhabditidae and Steinernematidae to sugarcane shoot borer Chilo infuscatellus Snellen was investigated at 18 and 27"C under... more
Infectivity of twenty nine entomopathogenic nematode (EPN) isolates belonging to the families of Heterorhabditidae and Steinernematidae to sugarcane shoot borer Chilo infuscatellus Snellen was investigated at 18 and 27"C under laboratory conditions. Although all the EPN ...
Research Interests:
The infectivity of an Indian isolate of Pasteuria penetrans (PMI-1) to isolates of the entomopathogenic nematodes Steinernema sp. and Heterorhabditis sp. was tested in aqueous suspensions. Spores of P. penetrans did not attach to any of... more
The infectivity of an Indian isolate of Pasteuria penetrans (PMI-1) to isolates of the entomopathogenic nematodes Steinernema sp. and Heterorhabditis sp. was tested in aqueous suspensions. Spores of P. penetrans did not attach to any of the entomopathogenic nematodes even after 72 ...
Research Interests:
Spore attachment to second-stage juveniles of Meloidogyne incognita increased with the increase in Pasteuria penetrans spore density level from 1.5 to 3.5 g parasite preparation/kg sand. Number of nematodes penetrating the roots, gall... more
Spore attachment to second-stage juveniles of Meloidogyne incognita increased with the increase in Pasteuria penetrans spore density level from 1.5 to 3.5 g parasite preparation/kg sand. Number of nematodes penetrating the roots, gall formation as well as total ...
Research Interests: Biological Sciences, Organic Farming, Environmental Sciences, Food web, Nitrogen, and 14 moreParticulate organic matter, Soybean, Reduced Tillage, Microbial Biomass, Weed Control, Community Organization, FARMING SYSTEM, Indexation, Transition Period, Organic Matter, Soil Bulk Density, Conventional Farming, Soil microbial biomass, and Chisel Plow
Research Interests:
Research Interests:
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The effectiveness of four entomopathogenic nematodes (EPN) viz., Heterorhabditis indica (isolate LN2), 11. bacteriophora, Steinernema glaseri and S. riobrave against pupae and adult beetles of Holotrichia serrata F., ~i serious pest of... more
The effectiveness of four entomopathogenic nematodes (EPN) viz., Heterorhabditis indica (isolate LN2), 11. bacteriophora, Steinernema glaseri and S. riobrave against pupae and adult beetles of Holotrichia serrata F., ~i serious pest of sugarcane was evaluated in the laboratory. All ...
Research Interests: Nematology, Agricultural Biotechnology, Biological Control, Entomopathogenic nematodes, Laboratory experiment, and 10 moreUrban Trees, Plant Protection, Biocontrol Science and Technology, Tuta Absoluta, Ecological Applications, Urban Park, Entomopathogenic Nematode, Laboratory Tests, Dacus Cilliatus, and ENVIRONMENTAL SCIENCE AND MANAGEMENT
In Arabidopsis, non-expressor of pathogenesis related genes-1, NPR1 has been shown to be a positive regulator of the salicylic acid controlled systemic acquired resistance pathway and modulates the cross talk between SA and JA signaling.... more
In Arabidopsis, non-expressor of pathogenesis related genes-1, NPR1 has been shown to be a positive regulator of the salicylic acid controlled systemic acquired resistance pathway and modulates the cross talk between SA and JA signaling. Transgenic plants expressing AtNPR1 constitutively exhibited resistance against pathogens as well as herbivory. In the present study, tobacco transgenic plants expressing AtNPR1 were studied further for their response to infection by the sedentary endoparasitic root knot nematode, Meloidogyne incognita. Transgenic plants showed enhanced resistance against the root-knot nematode infection. Prominent differences in the shoot and root weights of wild type and transgenic plants were observed post-inoculation with M. incognita. This was associated with a decrease in the number of root galls and egg masses in transgenic plants compared to WT. The transgenic plants also showed constitutive and induced expression of some PR protein genes, when challenged with M. incognita.