MSc

The study on “Screening of cassava genotype for cassava mosaic disease
resistance” was conducted at the ICAR- Central Tuber Crop Research Institute,
Sreekariyam, Thiruvananthapuram during 2019-2020.
The objective of the study was to screen the cassava breeding lines for resistance
to cassava mosaic disease. The screening was carried out in fifteen selected cassava
breeding lines from the breeding programme to analyze their resistance to cassava mosaic
disease (CMD).
For the analysis of resistance, virus inoculum was introduced into the fifteen
breeding lines by grafting. Chip bud grafting method was carried out to analyze the
resistance of breeding lines. The Sri Lankan cassava mosaic virus (SLCMV) infected
plants, confirmed through multiplex PCR were selected as the inoculum source (scion)
for grafting.
Periodic observations were carried out in grafted plants by morphological
(symptom appearance) as well as molecular analysis by means of ELISA and PCR. None
of the grafted cassava plants showed any mosaic symptoms in the new shoots developed.
PCR, ELISA and qPCR results revealed that the presence of SLCMV was only confirmed
to the control plants (susceptible cv. H-226) and were absent in the breeding lines tested.
This confirmed the 15 breeding lines screened are resistant to cassava mosaic disease
caused by SLCMV.
CMD resistant cassava varieties have an effective role in minimizing the damage
caused by the virus. The success of grafting suggests this technique as the most efficient
one for virus transmission and the resistant screening programme. The rapid selection of
CMD resistance lines can be offered by this technique.
The CMD resistance breeding lines have a better role in on-farm production as
well as in the breeding programme.