Transport van X-virus in de aardappel (Solanum tuberosum L.) bij primaire infectie

The time needed for potato virus X to reach the tubers from the inoculated leaf depended closely on the age of the potato plant. In young plants the virus could be detected in the tubers after about five days. However in the period of maximum tuber formation, virus translocation occurred only incidentally. The phenomenon of gradually decreased speed of virus translocation was called old-age resistance. It also played a part in infections with aphid-borne viruses such as potato leafroll virus and virus Y. It had practical significance for the production of seed potatoes as it was already noticeable in the period of highest aphid populations. When potato plants were inoculated in an advanced stage of development only part of the vegetative progeny got infected. This meant that a plant produced infected and uninfected tubers, and also that a single tuber had infected as well as uninfected parts. The bigger tubers of a primarily infected plant were more often infected than smaller ones. Moreover, the eyes at the top end of the tuber had a greater chance of attracting infection than those occurring close to the heel end.<p/