SPORE GERMINATION 



Log concentration L-lysine 

 Hydrochloride, mg per liter 



Figure 5. The response to 

 graded doses of lysine of 

 macroconidia of a lysine-requir- 

 ing mutant of Neurospora crassa. 

 Redrawn from Ryan (240), by 

 permission of the American 

 Journal of Botany. 



produce macroconidia which require the amino acid for prompt germi- 

 nation, although the spores will germinate in time without the com- 

 pound (239, 240). The response of one such mutant to lysine is shown 

 in Figure 5. The assay is complicated by the fact that amino acids are 

 somewhat inhibitory to spore germination in both mutant and normal 

 Neurospora crassa. Parathiotrophic mutants of Aspergillus nidulans 

 respond in the same way to sulfur compounds (252). 



Hypoxanthine, partially replaced by guanine, accelerates both spore 

 germination and early growth of Phycomyces blakesleeanus (226, 227, 

 228, 229, 230, 231, 233, 238). The effect of organic acids and of various 

 physical and chemical treatments in increasing spore germination in 

 this species has tentatively been ascribed to their influence on the avail- 

 ability of hypoxanthine (232). 



Although, as mentioned above, complex biological materials improve 

 germination in many species, relatively few vitamin requirements for 

 spore germination have been worked out: Memnoniella echinata re- 

 quires biotin (216), Myrothecium verrucaria also needs biotin but only 

 in the phase following germ tube emergence (189), and Colletotrichum 

 gloeosporioides is reported, without data, to respond to riboflavin and 

 other vitamins (61). As discussed briefly in Chapter 10, successful use 

 of the differential germination method for the detection of vitamin- 

 deficient mutants implies that these mutants require the factor for spore 

 germination as well as for growth. Promotion of basidiospore germi- 

 nation by co-culture with Torulopsis sanguinea is at least suggestive of 

 a vitamin effect (94, 95), as is also the observation that the parent my- 

 celium itself stimulates spore germination in Psalliota campestris (76). 



Germination of uredospores of Melampsora lini is increased by 

 methyl-p-hydroxybenzoate and by aureomycin (288); there is, however, 



