The apical meristem is the best part of the plant for making virus-free plants because it is the region where the plant growth occurs and it contains actively dividing cells. These actively dividing cells can be used to produce new tissues and organs of the plant in a process called tissue culture. Since the apical meristem is usually free of viruses, it can be used to produce virus-free plants. This technique is called meristem culture or shoot-tip grafting.