Q.Virus free plants are developed from :

Field-grown perennial crops are routinely infected by pathogens - fungi, bacteria, mycoplasma and viruses - that cause substantial economic losses, and while chemical treatment can generally control fungal and bacterial infections, it is largely ineffective against viruses. Shoot meristem tip culture is the technique used to produce virus-free plants, because the apical meristem of an infected plant is characteristically free of virus even when the rest of the plant carries the infection. The standard protocol excises an apical meristem tip carrying one or two leaf primordia under sterile conditions, cultures it in vitro in solid MS medium supplemented with growth hormones, holds the culture in the dark at 24 degC +/- 1 degC for three days before switching to normal illumination (about 2400 lux …