BSc- MSc

The study entitled “In-vitro chemotherapy for inducing tolerance towards
Tomato Leaf Curl New Delhi virus in bitter gourd (Momordica charantia L.)” was
conducted at the Department of Molecular Biology and Biotechnology, College of
Agriculture, Vellayani, Thiruvananthapuram during 2022-23. The objective of the
study was the evaluation of in-vitro treatment with antiviral compounds, viz.,
Ribavirin, Virus–Ex and extracts of Bougainvillea spectabilis for inducing tolerance
towards Begomovirus- ToLCNDV in bitter gourd (Momordica charantia L.). The
explants namely seed of bitter gourd variety Preethi was collected from,
Instructional farm, College of agriculture, Vellayani.
Seeds were subjected to hot water treatment at 55°C for 15 minutes, followed
by washing in 0.2% bavistin for 15 minutes and kept in dark for inducing
germination. 91.2% germination was noticed in 3 days. The germinated seeds were
grown in Murashige and Skoog (MS) medium supplemented with 2ppm BA and
20ppm concentration of various antiviral compounds viz., Ribavirin (Treatment 1),
Virus-Ex (Treatment 2), extract of Bougainvillea spectabilis (Treatment 3) along
with control.
Percentage of culture establishment was found to be maximum (65.25%) in
ribavirin treated plants followed by virus ex and bougainvillea. 20 days old in-vitro
grown plants were hardened in coir pith compost and the biometric observations
were taken and compared. Significant increase in plant height and number of leaves
over control was noticed in treatment using ribavirin and virus ex respectively.
DNA was isolated from 20 day old (hardened) treated and control plants prior
to whitefly transmission and were confirmed to be virus free using PCR.
Whitefly mediated artificial inoculation of virus in hardened plants (25 day
old) was done and the plants were maintained inside insect proof cage for symptom
development. Symptoms were observed in control plants after 10 days of whitefly
transmission. Further PCR was performed to confirm the presence/absence of
Begomovirus. Absence of virus in treatments with ribavirin and virus ex were
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confirmed in PCR. Treatment using extracts of bougainvillea did not show any
symptoms but confirmed positive in molecular detection. The control plants which
developed symptoms was found positive in PCR.
Peroxidase assay (Lobenstein and Linsey method) showed maximum increase
in activity (3-fold) in plants treated with ribavirin followed by extracts of
bougainvillea (2-fold) three days after whitefly transmission.
Biometric observations on 35th day viz., plant height, number of leaves and
leaf area were found higher in all the treatments compared to control, out of which
treatment using ribavirin was found to be highly significant for all the parameters.
To conclude, the present study in bitter gourd could confirm the antiviral
activity of ribavirin and virus ex towards Begomovirus through whitefly mediated
transmission test and molecular detection using PCR.