ROUND TABLE DISCUSSION 223 



(VII) Proposals for Future Work 



Moderator: Let us consider finally experiments still to be 

 performed on the induction and the breaking of dormancy in 

 the different biological classes. 



Halvorson Jr. : A simple explanation for many dormancies 

 is that they are simply expressions of an anhydrous condition. 

 A way of investigating this might be the exposure of a system to 

 deuteriated or tritiated water. Then after rupturing the tissue in 

 a non-aqueous solvent, we could look for deuterium or tritium 

 on some recognisable internal component. One would then find 

 whether water could enter such a component. The other question 

 is whether there is any metabolism in the anhydrous system. We 

 might be able to decide this point by determining whether there 

 is incorporation of ^'-P into ATP within the 'anhydrous' cell. 



Jashphe: It might be very important to determine whether 

 variations in the permeation barrier accompany the induction 

 and breaking of dormancy. 



Halvorson: I agree this is very important, but the design of 

 a suitable experiment on this is a very difficult problem. 



Mayer: In bacterial spores, it is very often a heat shock that 

 breaks dormancy. In seeds too, a heat shock of short duration 

 and at moderately high temperature performs the same function. 

 All this seems to point to some change in the physical structure. 

 However, I have no idea how to establish what this structure is. 



Wahl: I have two suggestions. One is based on the obser- 

 vation that when we inoculate oat seedlings in one-leaf stage 

 with uredospores of race 2 of Puccinia graminis avenae, uredia 

 are produced on the leaf and teHa are formed on the coleoptyle. 

 In other words, the same inoculum produced the active stage 

 of the rust fungus on the leaf and the dormant stage on the 

 coleoptyle. The question arises why does a similar genetic stock 

 yield on the same plant dormant and non-dormant spores, 

 depending only on the kind of tissue used as a host. The second 

 proposal stems from Yarwood's studies on the powdery mildew 

 of red clover, Erysiphe polygoni. Conidiospores collected during 



