Thumbnail Image

Chaudhary Charan Singh Haryana Agricultural University, Hisar

Chaudhary Charan Singh Haryana Agricultural University popularly known as HAU, is one of Asia's biggest agricultural universities, located at Hisar in the Indian state of Haryana. It is named after India's seventh Prime Minister, Chaudhary Charan Singh. It is a leader in agricultural research in India and contributed significantly to Green Revolution and White Revolution in India in the 1960s and 70s. It has a very large campus and has several research centres throughout the state. It won the Indian Council of Agricultural Research's Award for the Best Institute in 1997. HAU was initially a campus of Punjab Agricultural University, Ludhiana. After the formation of Haryana in 1966, it became an autonomous institution on February 2, 1970 through a Presidential Ordinance, later ratified as Haryana and Punjab Agricultural Universities Act, 1970, passed by the Lok Sabha on March 29, 1970. A. L. Fletcher, the first Vice-Chancellor of the university, was instrumental in its initial growth.

Browse

20221
Reset filters
Subject: Microbiology × Author: Antil, Sonam × Start date: 1998 × Thesis Type: Ph.D ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    Studies on antagonistic activity of bacteria against root knot nematode(s)
    (CCSHAU Hisar, 2022-09) Antil, Sonam; Pathak, D.V.
    Root-knot nematodes under the genus Meloidogyne are world widely distributed plant parasites that cause serious damages to many important agricultural crops such as potato, cotton, tomato, brinjal, etc. Bacteria associated with roots and rhizosphere of many plant species have been extensively tested for the control of various soil borne pathogens including plant parasitic nematodes. Four bacterial isolates- KMT-4, KMT-5, KMT-8 and KMS-6 were originally isolated from nematode infested rhizospheric soil belonging to research field of Department of Nematology, CCS HAU, Hisar and have demonstrated potential nematicidal activity against root-knot nematode Meloidogyne javanica. All the isolates showed HCN and siderophore production but chitinase activity was exhibited by KMT-5 only. The bacteria were identified based on 16S rRNA gene sequence analysis as: Bacillus aryabhattai (KMT-4), B. cereus (KMT-5), B. megaterium (KMT-8), B. altitudinis (KMS-6). For in vitro bioassays, M. javanica eggs were isolated from infected roots and juveniles (J2) were obtained through MBFT. Effect of bacterial strains on egg hatching and J2 mortality was checked by preparing the extracellular and intracellular extracts of all four bacterial strains and tested their activity on M. javanica eggs and J2. The larval mortality and egg-hatching inhibition rates of M. javanica were increased with the rising concentration of extracellular extracts of all the bacterial strains and the duration of exposure. A pot experiment was also planned in spring 2021 on tomato to check the genetic stability of the bacterial strains. All four bacteria reduced nematode infection and promoted plant growth far better than control and chemical treatment as well. The nematicidal bacterial extracts were subjected to crude extraction from extracellular and intracellular extracts for proteinaceous as well as non-proteinaceous nematicidal compound(s). Crude extraction done for extracellular non-proteinaceous was found potent of all the bacterial strains when tested against M. javanica eggs and J2 with B. cereus KMT-5 showing maximum activity. Thus, this study aimed to separate, purify, and identify nematicidal compound from B. cereus KMT-5 and to validate its anti-M. javanica activities. Compound was purified through silica gel column chromatography using ethyl acetate: methanol as mobile phase with increasing polarity gradient and fractions obtained were checked via thin-layer chromatography. Similar fractions were combined and tested against M. javanica eggs and J2. Out of five subfractions, subfraction III (FIII) showed maximum activity. The nematicidal compound from FIII was extracted via prepTLC and subjected to HPLC. Structural identification was conducted through H1-nuclear magnetic resonance (NMR) spectroscopy. The nematicidal compound was identified as phytosphingosine based on H1-NMR shifts and structure was in silico verified using MestReNova 14.2 software. Purified nematicidal compound phytosphingosine from B. cereus KMT-5 was then tested against M. javanica eggs and J2. Only 5.6 J2 were obtained after 96h of treatment with phytosphingosine whereas in control there were 98.0 J2 showing a significant difference in hatching rate. The mortality rate of M. javanica J2 reached to 94.6% after 72h of exposure to phytosphingosine.