Virus indexing:
- It is the process of detection of presence of virus in plants using various techniques.
Methods of virus indexing
a) Sap transmission test:
- Virus are taken from the test plant
- Grinding with a mortar or pestle
- Sap is smeared onto the leaf of an indicator plant.
- If virus present in the sap, the indicator shows symptoms of concerned virus.
b) Serological test/ ELISA test:
- Done based on antibody reaction.
- Add a drop of centrifuged sap from a test plant to a drop of antiserum
- If virus present precipitates because of presence of specific antibody in the blood.
c) DNA finger prints:
- Which exhibit no visible symptoms.
d) Visible symptoms