IMMUNITY OF POTATO VARIETIES FROM ATTACK BY THE WART DISEASE FUNGUS, SYNCHYTRIUM ENDOB IOTICUM (SCHILB.) PERC.

Abstract

Summary. It is known that grafting together portions of two different plants is sometimes followed by changes in their chemical contents owing to permeation of each by substances formed in the other. The present investigation is an attempt to determine by grafting together pieces of immune and susceptible plants whether the cause of immunity from wart disease of potatoes is carried by chemical compounds which can traverse unchanged a graft fusion layer or by those which are unable so to do. For this purpose all the eight possible types of plants have been built up by grafting together root, shoot and tuber systems from either immune or susceptible plants. In none of the experiments was the reaction of the tubers towards wart disease seen to be changed. The deduction is therefore drawn that the cause of the immunity is not carried by any compound which is able to traverse the plant. In this way the problem is considerably narrowed down, for it is now possible to eliminate many lines of attack as unlikely to be fruitful. The suggestion is put forward that the examination of the proteins from immune and susceptible varieties by immunochemical methods is the most hopeful future line of attack.