Abstract:
In uninoculated tobacco leaves a relationship is established between the time of systemic invasion by infectious TMV and the type of mosaic symptom pattern which subsequently develops: leaves larger than approximately 2.5 cm at the time of invasion do not subsequently show dark green areas, leaves less than 1.4 cm at the time of invasion show dark green areas in various patterns.
It is established that the palisade cell number continues to increase substantially until the leaf is about 15 cm in length. An average of approximately seven exponential generations of cells would account for the 100 fold increase in palisade cell number that takes place as the leaf grows from 1.4 cm to maturity.