When trying to salvage a highly valuable crop variety that has been systematically infected with a pathogen, which of the following explants must be cultured to successfully recover healthy, disease-free plants?

Step-by-step solution

Even if a plant is systemically infected with a pathogen such as a virus, the apical and axillary meristems remain generally free of the infection. This is primarily because the rate of cell division in the meristematic region is much faster than the rate of multiplication and systemic spread of the pathogen. Additionally, the vascular tissue, which often transports pathogens, is not fully differentiated or connected in the extreme apical regions. Therefore, to successfully recover healthy, disease-free plants from