394 



SPORE GERMINATION 



240 



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Time, hours 



Figure 2. Oxygen consumption of activated (curve 1) and dormant (curve 2) 

 ascospores of Neurospora tetrasperma. The arrow marks the time of appearance of 

 germ tubes. Redrawn from Goddard and Smith (110), by permission of Plant 

 Physiology. 



the appearance o[ the germ tube; this particular type of curve is not 

 universal in the fungi and would not necessarily occur under different 

 conditions of nutrient or oxygen supply. Endogenous respiration in 

 Memnoniella echinata and Aspergillus luchuensis is affected by ammo- 

 nium ion and by the previous cultural history of the spore population 

 (64). Oxygen pressure also affects the endogenous rate (110, 194). 



Spores generally, but not always, respond to added substrates by an 

 increase in respiratory rate; increases may also be induced by provision 

 of nitrogen or of complex nutrients in addition to a carbon source (173, 

 193, 254, 255). The data of Table 2 are fairly typical in that the range 

 of response is from zero to high; since, however, the substrate was su- 

 crose, the results reflect hydrolytic as well as respiratory capacities. 



Just as mature mycelium, spores of a given species may or may not 

 ferment glucose anaerobically. Uredospores of Puccinia graminis tri- 

 tici do not form carbon dioxide anaerobically (254); at the other ex- 

 treme, both activated ascospores and conidia of Neurospora spp. fer- 

 ment vigorously and have demonstrable glycolytic enzymes (59, 110, 

 209). 



Not much can be said at this time of detailed respiratory pathways 

 in spores. Acids of the tricarboxylic cycle are oxidized by conidia of 

 Neurospora sitophila, are found in conidial homogenates, and appear 

 in the medium during germination (174, 208, 293). Poisons which 

 affect glycolysis and the cytochrome system usually inhibit spore res- 

 piration, but several anomalies in the results make interpretation dif- 



